TMS320x2833x, 2823x Enhanced Pulse Width

TMS320x2833x, 2823x Enhanced Pulse Width
TMS320x2833x, 2823x Enhanced Pulse Width
Modulator (ePWM) Module
Reference Guide
Literature Number: SPRUG04A
October 2008 – Revised July 2009
2
SPRUG04A – October 2008 – Revised July 2009
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Preface ....................................................................................................................................... 8
1
Introduction ...................................................................................................................... 11
.................................................................................................. 11
...................................................................................................... 15
2
ePWM Submodules ............................................................................................................ 17
2.1
Overview ................................................................................................................ 17
2.2
Time-Base (TB) Submodule .......................................................................................... 20
2.3
Counter-Compare (CC) Submodule ................................................................................. 31
2.4
Action-Qualifier (AQ) Submodule .................................................................................... 37
2.5
Dead-Band Generator (DB) Submodule ............................................................................ 51
2.6
PWM-Chopper (PC) Submodule ..................................................................................... 55
2.7
Trip-Zone (TZ) Submodule ........................................................................................... 59
2.8
Event-Trigger (ET) Submodule ....................................................................................... 63
3
Applications to Power Topologies ....................................................................................... 68
3.1
Overview of Multiple Modules ........................................................................................ 68
3.2
Key Configuration Capabilities ....................................................................................... 68
3.3
Controlling Multiple Buck Converters With Independent Frequencies .......................................... 69
3.4
Controlling Multiple Buck Converters With Same Frequencies .................................................. 73
3.5
Controlling Multiple Half H-Bridge (HHB) Converters ............................................................. 76
3.6
Controlling Dual 3-Phase Inverters for Motors (ACI and PMSM) ................................................ 78
3.7
Practical Applications Using Phase Control Between PWM Modules .......................................... 82
3.8
Controlling a 3-Phase Interleaved DC/DC Converter ............................................................. 83
3.9
Controlling Zero Voltage Switched Full Bridge (ZVSFB) Converter ............................................. 87
4
Registers .......................................................................................................................... 90
4.1
Time-Base Submodule Registers .................................................................................... 90
4.2
Counter-Compare Submodule Registers ........................................................................... 94
4.3
Action-Qualifier Submodule Registers .............................................................................. 97
4.4
Dead-Band Submodule Registers .................................................................................. 101
4.5
PWM-Chopper Submodule Control Register ..................................................................... 103
4.6
Trip-Zone Submodule Control and Status Registers ............................................................ 105
4.7
Event-Trigger Submodule Registers ............................................................................... 108
4.8
Proper Interrupt Initialization Procedure ........................................................................... 113
Appendix A Revision History ..................................................................................................... 114
1.1
Submodule Overview
1.2
Register Mapping
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Table of Contents
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List of Figures
1
Multiple ePWM Modules .................................................................................................. 13
2
Submodules and Signal Connections for an ePWM Module ........................................................ 14
3
ePWM Submodules and Critical Internal Signal Interconnects...................................................... 15
4
Time-Base Submodule Block Diagram ................................................................................. 20
5
Time-Base Submodule Signals and Registers ........................................................................ 21
6
Time-Base Frequency and Period
23
7
Time-Base Counter Synchronization Scheme 1
25
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Counter-Compare Events In Up-Down-Count Mode, TBCTL[PHSDIR = 0] Count Down On
Synchronization Event ................................................................................................... 37
19
Counter-Compare Events In Up-Down-Count Mode, TBCTL[PHSDIR = 1] Count Up On Synchronization
Event ....................................................................................................................... 37
20
Action-Qualifier Submodule .............................................................................................. 38
21
Action-Qualifier Submodule Inputs and Outputs
22
Possible Action-Qualifier Actions for EPWMxA and EPWMxB Outputs ............................................ 40
23
Up-Down-Count Mode Symmetrical Waveform ....................................................................... 43
24
Up, Single Edge Asymmetric Waveform, With Independent Modulation on EPWMxA and
EPWMxB—Active High ................................................................................................... 44
25
Up, Single Edge Asymmetric Waveform With Independent Modulation on EPWMxA and
EPWMxB—Active Low .................................................................................................... 45
26
Up-Count, Pulse Placement Asymmetric Waveform With Independent Modulation on EPWMxA
27
Up-Down-Count, Dual Edge Symmetric Waveform, With Independent Modulation on EPWMxA and
EPWMxB — Active Low .................................................................................................. 48
28
Up-Down-Count, Dual Edge Symmetric Waveform, With Independent Modulation on EPWMxA and
EPWMxB — Complementary ............................................................................................ 49
29
Up-Down-Count, Dual Edge Asymmetric Waveform, With Independent Modulation on EPWMxA—Active
Low .......................................................................................................................... 50
30
Dead_Band Submodule .................................................................................................. 51
31
Configuration Options for the Dead-Band Submodule
32
33
34
35
36
4
......................................................................................
......................................................................
Time-Base Counter Synchronization Scheme 2 ......................................................................
Time-Base Counter Synchronization Scheme 3 ......................................................................
Time-Base Up-Count Mode Waveforms................................................................................
Time-Base Down-Count Mode Waveforms ............................................................................
Time-Base Up-Down-Count Waveforms, TBCTL[PHSDIR = 0] Count Down On Synchronization Event .....
Time-Base Up-Down Count Waveforms, TBCTL[PHSDIR = 1] Count Up On Synchronization Event.........
Counter-Compare Submodule ...........................................................................................
Detailed View of the Counter-Compare Submodule ..................................................................
Counter-Compare Event Waveforms in Up-Count Mode ............................................................
Counter-Compare Events in Down-Count Mode ......................................................................
......................................................................
.............
...............................................................
Dead-Band Waveforms for Typical Cases (0% < Duty < 100%) ....................................................
PWM-Chopper Submodule ...............................................................................................
PWM-Chopper Submodule Operational Details .......................................................................
Simple PWM-Chopper Submodule Waveforms Showing Chopping Action Only .................................
PWM-Chopper Submodule Waveforms Showing the First Pulse and Subsequent Sustaining Pulses ........
39
46
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57
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PWM-Chopper Submodule Waveforms Showing the Pulse Width (Duty Cycle) Control of Sustaining
Pulses ....................................................................................................................... 58
38
Trip-Zone Submodule ..................................................................................................... 59
39
Trip-Zone Submodule Mode Control Logic
40
Trip-Zone Submodule Interrupt Logic ................................................................................... 63
41
Event-Trigger Submodule ................................................................................................ 63
............................................................................
List of Figures
62
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42
Event-Trigger Submodule Inter-Connectivity of ADC Start of Conversion ......................................... 64
43
Event-Trigger Submodule Showing Event Inputs and Prescaled Outputs ......................................... 65
44
Event-Trigger Interrupt Generator ....................................................................................... 66
45
Event-Trigger SOCA Pulse Generator .................................................................................. 67
46
Event-Trigger SOCB Pulse Generator .................................................................................. 67
47
Simplified ePWM Module ................................................................................................. 68
48
EPWM1 Configured as a Typical Master, EPWM2 Configured as a Slave
49
Control of Four Buck Stages. Here FPWM1≠ FPWM2≠ FPWM3≠ FPWM4
50
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....................................... 69
.................................................... 70
Buck Waveforms for (Note: Only three bucks shown here).......................................................... 71
Control of Four Buck Stages. (Note: FPWM2 = N x FPWM1) .............................................................. 73
Buck Waveforms for (Note: FPWM2 = FPWM1)) ............................................................................. 74
Control of Two Half-H Bridge Stages (FPWM2 = N x FPWM1) ............................................................ 76
Half-H Bridge Waveforms for (Note: Here FPWM2 = FPWM1 ) ............................................................ 77
Control of Dual 3-Phase Inverter Stages as Is Commonly Used in Motor Control ............................... 79
3-Phase Inverter Waveforms for (Only One Inverter Shown) ....................................................... 80
Configuring Two PWM Modules for Phase Control ................................................................... 82
Timing Waveforms Associated With Phase Control Between 2 Modules .......................................... 83
Control of a 3-Phase Interleaved DC/DC Converter .................................................................. 84
3-Phase Interleaved DC/DC Converter Waveforms for .............................................................. 85
Controlling a Full-H Bridge Stage (FPWM2 = FPWM1) ..................................................................... 87
ZVS Full-H Bridge Waveforms ........................................................................................... 88
Time-Base Period Register (TBPRD) ................................................................................... 90
Time-Base Phase Register (TBPHS) ................................................................................... 90
Time-Base Counter Register (TBCTR) ................................................................................. 90
Time-Base Control Register (TBCTL) .................................................................................. 91
Time-Base Status Register (TBSTS) ................................................................................... 93
Counter-Compare A Register (CMPA) ................................................................................. 94
Counter-Compare B Register (CMPB).................................................................................. 94
Counter-Compare Control Register (CMPCTL) ....................................................................... 96
Compare A High Resolution Register (CMPAHR) ................................................................... 97
Action-Qualifier Output A Control Register (AQCTLA) ............................................................... 97
Action-Qualifier Output B Control Register (AQCTLB) ............................................................... 98
Action-Qualifier Software Force Register (AQSFRC) ................................................................. 99
Action-Qualifier Continuous Software Force Register (AQCSFRC) ............................................... 100
Dead-Band Generator Control Register (DBCTL) ................................................................... 101
Dead-Band Generator Rising Edge Delay Register (DBRED) ..................................................... 103
Dead-Band Generator Falling Edge Delay Register (DBFED) ..................................................... 103
PWM-Chopper Control Register (PCCTL) ............................................................................ 103
Trip-Zone Select Register (TZSEL) .................................................................................... 105
Trip-Zone Control Register (TZCTL) .................................................................................. 106
Trip-Zone Enable Interrupt Register (TZEINT) ....................................................................... 106
Trip-Zone Flag Register (TZFLG) ...................................................................................... 107
Trip-Zone Clear Register (TZCLR) .................................................................................... 107
Trip-Zone Force Register (TZFRC) .................................................................................... 108
Event-Trigger Selection Register (ETSEL) ........................................................................... 108
Event-Trigger Prescale Register (ETPS) ............................................................................. 109
Event-Trigger Flag Register (ETFLG) ................................................................................. 111
Event-Trigger Clear Register (ETCLR)................................................................................ 112
Event-Trigger Force Register (ETFRC) ............................................................................... 112
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List of Figures
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List of Tables
1
ePWM Module Control and Status Register Set Grouped by Submodule ......................................... 16
2
Submodule Configuration Parameters .................................................................................. 17
3
Time-Base Submodule Registers ....................................................................................... 21
4
Key Time-Base Signals ................................................................................................... 22
5
Counter-Compare Submodule Registers
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
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29
30
31
32
33
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35
36
37
38
39
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43
44
45
46
47
6
.............................................................................. 32
Counter-Compare Submodule Key Signals ............................................................................ 33
Action-Qualifier Submodule Registers .................................................................................. 38
Action-Qualifier Submodule Possible Input Events ................................................................... 39
Action-Qualifier Event Priority for Up-Down-Count Mode ............................................................ 41
Action-Qualifier Event Priority for Up-Count Mode .................................................................... 41
Action-Qualifier Event Priority for Down-Count Mode ................................................................ 41
Behavior if CMPA/CMPB is Greater than the Period ................................................................. 41
Dead-Band Generator Submodule Registers .......................................................................... 51
Classical Dead-Band Operating Modes ............................................................................... 53
Dead-Band Delay Values in μS as a Function of DBFED and DBRED ........................................... 54
PWM-Chopper Submodule Registers .................................................................................. 55
Possible Pulse Width Values for SYSCLKOUT = 100 MHz ......................................................... 57
Trip-Zone Submodule Registers ......................................................................................... 60
Possible Actions On a Trip Event ....................................................................................... 61
Event-Trigger Submodule Registers ................................................................................... 65
Time-Base Period Register (TBPRD) Field Descriptions ............................................................ 90
Time-Base Phase Register (TBPHS) Field Descriptions ............................................................. 90
Time-Base Counter Register (TBCTR) Field Descriptions ........................................................... 90
Time-Base Control Register (TBCTL) Field Descriptions ............................................................ 91
Time-Base Status Register (TBSTS) Field Descriptions ............................................................. 93
Counter-Compare A Register (CMPA) Field Descriptions ........................................................... 94
Counter-Compare B Register (CMPB) Field Descriptions ........................................................... 95
Counter-Compare Control Register (CMPCTL) Field Descriptions ................................................ 96
Compare A High Resolution Register (CMPAHR) Field Descriptions .............................................. 97
Action-Qualifier Output A Control Register (AQCTLA) Field Descriptions ........................................ 97
Action-Qualifier Output B Control Register (AQCTLB) Field Descriptions ........................................ 98
Action-Qualifier Software Force Register (AQSFRC) Field Descriptions .......................................... 99
Action-qualifier Continuous Software Force Register (AQCSFRC) Field Descriptions ......................... 100
Dead-Band Generator Control Register (DBCTL) Field Descriptions ............................................. 102
Dead-Band Generator Rising Edge Delay Register (DBRED) Field Descriptions............................... 103
Dead-Band Generator Falling Edge Delay Register (DBFED) Field Descriptions .............................. 103
PWM-Chopper Control Register (PCCTL) Bit Descriptions ....................................................... 104
Trip-Zone Submodule Select Register (TZSEL) Field Descriptions .............................................. 105
Trip-Zone Control Register (TZCTL) Field Descriptions ............................................................ 106
Trip-Zone Enable Interrupt Register (TZEINT) Field Descriptions ................................................ 106
Trip-Zone Flag Register (TZFLG) Field Descriptions ............................................................... 107
Trip-Zone Clear Register (TZCLR) Field Descriptions ............................................................. 108
Trip-Zone Force Register (TZFRC) Field Descriptions ............................................................. 108
Event-Trigger Selection Register (ETSEL) Field Descriptions .................................................... 109
Event-Trigger Prescale Register (ETPS) Field Descriptions ...................................................... 110
Event-Trigger Flag Register (ETFLG) Field Descriptions ........................................................... 111
Event-Trigger Clear Register (ETCLR) Field Descriptions ......................................................... 112
List of Tables
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49
........................................................
Changes for this Revision...............................................................................................
Event-Trigger Force Register (ETFRC) Field Descriptions
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List of Tables
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112
114
7
Preface
SPRUG04A – October 2008 – Revised July 2009
Read This First
The Enhanced Pulse Width Modulator (ePWM) module described in this reference guide is a Type 0
ePWM. See the TMS320x28xx, 28xxx DSP Peripheral Reference Guide (SPRU566) for a list of all
devices with a ePWM module of the same type, to determine the differences between the types, and for a
list of device-specific differences within a type. This reference guide includes an overview of the module
and information about each of its sub-modules:
• Time-Base Module
• Counter Compare Module
• Action Qualifier Module
• Dead-Band Generator Module
• PWM Chopper (PC) Module
• Trip Zone Module
• Event Trigger Module
Related Documentation From Texas Instruments
The following books describe the TMS320F2833x, 2823x module and related support tools that are
available on the TI website:
Data Manual and Errata—
SPRS439 — TMS320F28335, TMS320F28334, TMS320F28332, TMS320F28235, TMS320F28234,
TMS320F28232 Digital Signal Controllers (DSCs) Data Manual contains the pinout, signal
descriptions, as well as electrical and timing specifications for the F2833x/2823x devices.
SPRZ272 — TMS320F28335, TMS320F28334, TMS320F28332, TMS320F28235, TMS320F28234,
TMS320F28232 DSC Silicon Errata describes the advisories and usage notes for different
versions of silicon.
CPU User's Guides—
SPRU430 — TMS320C28x CPU and Instruction Set Reference Guide describes the central processing
unit (CPU) and the assembly language instructions of the TMS320C28x fixed-point digital signal
processors (DSPs). It also describes emulation features available on these DSPs.
SPRUEO2 — TMS320C28x Floating Point Unit and Instruction Set Reference Guide describes the
floating-point unit and includes the instructions for the FPU.
Peripheral Guides—
SPRU566 — TMS320x28xx, 28xxx DSP Peripheral Reference Guide describes the peripheral
reference guides of the 28x digital signal processors (DSPs).
SPRUFB0 — TMS320x2833x, 2823x System Control and Interrupts Reference Guide describes the
various interrupts and system control features of the 2833x and 2823x digital signal controllers
(DSCs).
SPRU812 — TMS320x2833x, 2823x Analog-to-Digital Converter (ADC) Reference Guide describes
how to configure and use the on-chip ADC module, which is a 12-bit pipelined ADC.
SPRU949 — TMS320x2833x, 2823x DSC External Interface (XINTF) Reference Guide describes the
XINTF, which is a nonmultiplexed asynchronous bus, as it is used on the 2833x and 2823x devices.
8
Preface
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Related Documentation From Texas Instruments
SPRU963 — TMS320x2833x, 2823x Boot ROM Reference Guide describes the purpose and features of
the bootloader (factory-programmed boot-loading software) and provides examples of code. It also
describes other contents of the device on-chip boot ROM and identifies where all of the information
is located within that memory.
SPRUFB7 — TMS320x2833x, 2823x Multichannel Buffered Serial Port (McBSP) Reference Guide
describes the McBSP available on the 2833x and 2823x devices. The McBSPs allow direct
interface between a DSP and other devices in a system.
SPRUFB8 — TMS320x2833x, 2823x Direct Memory Access (DMA) Module Reference Guide
describes the DMA on the 2833x and 2823x devices.
SPRUG04 — TMS320x2833x, 2823x Enhanced Pulse Width Modulator (ePWM) Module Reference
Guide describes the main areas of the enhanced pulse width modulator that include digital motor
control, switch mode power supply control, UPS (uninterruptible power supplies), and other forms of
power conversion.
SPRUG02 — TMS320x2833x, 2823x High-Resolution Pulse Width Modulator (HRPWM) Reference
Guide describes the operation of the high-resolution extension to the pulse width modulator
(HRPWM).
SPRUFG4 — TMS320x2833x, 2823x Enhanced Capture (eCAP) Module Reference Guide describes
the enhanced capture module. It includes the module description and registers.
SPRUG05 — TMS320x2833x, 2823x Enhanced Quadrature Encoder Pulse (eQEP) Module
Reference Guide describes the eQEP module, which is used for interfacing with a linear or rotary
incremental encoder to get position, direction, and speed information from a rotating machine in
high-performance motion and position control systems. It includes the module description and
registers.
SPRUEU1 — TMS320x2833x, 2823x Enhanced Controller Area Network (eCAN) Reference Guide
describes the eCAN that uses established protocol to communicate serially with other controllers in
electrically noisy environments.
SPRUFZ5 — TMS320x2833x, 2823x Serial Communications Interface (SCI) Reference Guide
describes the SCI, which is a two-wire asynchronous serial port, commonly known as a UART. The
SCI modules support digital communications between the CPU and other asynchronous peripherals
that use the standard non-return-to-zero (NRZ) format.
SPRUEU3 — TMS320x2833x, 2823x DSC Serial Peripheral Interface (SPI) Reference Guide
describes the SPI - a high-speed synchronous serial input/output (I/O) port - that allows a serial bit
stream of programmed length (one to sixteen bits) to be shifted into and out of the device at a
programmed bit-transfer rate.
SPRUG03 — TMS320x2833x, 2823x Inter-Integrated Circuit (I2C) Module Reference Guide describes
the features and operation of the inter-integrated circuit (I2C) module.
Tools Guides—
SPRU513 — TMS320C28x Assembly Language Tools v5.0.0 User's Guide describes the assembly
language tools (assembler and other tools used to develop assembly language code), assembler
directives, macros, common object file format, and symbolic debugging directives for the
TMS320C28x device.
SPRU514 — TMS320C28x Optimizing C/C++ Compiler v5.0.0 User's Guide describes the
TMS320C28x™ C/C++ compiler. This compiler accepts ANSI standard C/C++ source code and
produces TMS320 DSP assembly language source code for the TMS320C28x device.
SPRU608 — TMS320C28x Instruction Set Simulator Technical Overview describes the simulator,
available within the Code Composer Studio for TMS320C2000 IDE, that simulates the instruction
set of the C28x™ core.
SPRU625 — TMS320C28x DSP/BIOS 5.32 Application Programming Interface (API) Reference
Guide describes development using DSP/BIOS.
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Related Documentation From Texas Instruments
www.ti.com
Application Reports—
SPRAAM0 — Getting Started With TMS320C28x Digital Signal Controllers is organized by
development flow and functional areas to make your design effort as seamless as possible. Tips on
getting started with C28x™ DSP software and hardware development are provided to aid in your
initial design and debug efforts. Each section includes pointers to valuable information including
technical documentation, software, and tools for use in each phase of design.
SPRAAD5 — Power Line Communication for Lighting Applications Using Binary Phase Shift
Keying (BPSK) with a Single DSP Controller presents a complete implementation of a power line
modem following CEA-709 protocol using a single DSP.
SPRAA85 — Programming TMS320x28xx and 28xxx Peripherals in C/C++ explores a hardware
abstraction layer implementation to make C/C++ coding easier on 28x DSPs. This method is
compared to traditional #define macros and topics of code efficiency and special case registers are
also addressed.
SPRA958 — Running an Application from Internal Flash Memory on the TMS320F28xxx DSP covers
the requirements needed to properly configure application software for execution from on-chip flash
memory. Requirements for both DSP/BIOS™ and non-DSP/BIOS projects are presented. Example
code projects are included.
SPRAA91 — TMS320F280x Digital Signal Controller USB Connectivity Using the TUSB3410
USB-to-UART Bridge Chip presents hardware connections as well as software preparation and
operation of the development system using a simple communication echo program.
SPRAAD8 — TMS320x280x and TMS320F2801x ADC Calibration describes a method for improving
the absolute accuracy of the 12-bit ADC found on the TMS320x280x and TMS320F2801x devices.
Inherent gain and offset errors affect the absolute accuracy of the ADC. The methods described in
this report can improve the absolute accuracy of the ADC to levels better than 0.5%. This
application report has an option to download an example program that executes from RAM on the
F2808 EzDSP.
SPRAAI1 — Using the ePWM Module for 0% – 100% Duty Cycle Control provides a guide for the use
of the ePWM module to provide 0% to 100% duty cycle control and is applicable to the
TMS320x280x family of processors.
SPRAA88 — Using PWM Output as a Digital-to-Analog Converter on a TMS320F280x Digital Signal
Controller presents a method for utilizing the on-chip pulse width modulated (PWM) signal
generators on the TMS320F280x family of digital signal controllers as a digital-to-analog converter
(DAC).
SPRAAH1 — Using the Enhanced Quadrature Encoder Pulse (eQEP) Module in TMS320x280x,
28xxx as a Dedicated Capture provides a guide for the use of the eQEP module as a dedicated
capture unit and is applicable to the TMS320x280x, 28xxx family of processors.
SPRA820 — Online Stack Overflow Detection on the TMS320C28x DSP presents the methodology for
online stack overflow detection on the TMS320C28x DSP. C-source code is provided that contains
functions for implementing the overflow detection on both DSP/BIOS and non-DSP/BIOS
applications.
SPRA806 — An Easy Way of Creating a C-callable Assembly Function for the TMS320C28x DSP
provides instructions and suggestions to configure the C compiler to assist with C-callable
assembly routines.
TMS320C28x, C28x are trademarks of Texas Instruments.
10
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Reference Guide
SPRUG04A – October 2008 – Revised July 2009
TMS320x2833x, 2823x Enhanced Pulse Width Modulator
(ePWM) Module
The enhanced pulse width modulator (ePWM) peripheral is a key element in controlling many of the power
electronic systems found in both commercial and industrial equipments. These systems include digital
motor control, switch mode power supply control, uninterruptible power supplies (UPS), and other forms of
power conversion. The ePWM peripheral performs a digital to analog (DAC) function, where the duty cycle
is equivalent to a DAC analog value; it is sometimes referred to as a Power DAC.
This reference guide is applicable for ePWM type 0 . See the TMS320x28xx, 28xxx DSP Peripheral
Reference Guide (SPRU566) for a list of all devices with an ePWM module of the same type, to determine
the differences between the types, and for a list of device-specific differences within a type.
1
Introduction
An effective PWM peripheral must be able to generate complex pulse width waveforms with minimal CPU
overhead or intervention. It needs to be highly programmable and very flexible while being easy to
understand and use. The ePWM unit described here addresses these requirements by allocating all
needed timing and control resources on a per PWM channel basis. Cross coupling or sharing of resources
has been avoided; instead, the ePWM is built up from smaller single channel modules with separate
resources that can operate together as required to form a system. This modular approach results in an
orthogonal architecture and provides a more transparent view of the peripheral structure, helping users to
understand its operation quickly.
In this document the letter x within a signal or module name is used to indicate a generic ePWM instance
on a device. For example output signals EPWMxA and EPWMxB refer to the output signals from the
ePWMx instance. Thus, EPWM1A and EPWM1B belong to ePWM1 and likewise EPWM4A and EPWM4B
belong to ePWM4.
1.1
Submodule Overview
The ePWM module represents one complete PWM channel composed of two PWM outputs: EPWMxA
and EPWMxB. Multiple ePWM modules are instanced within a device as shown in Figure 1. Each ePWM
instance is identical with one exception. Some instances include a hardware extension that allows more
precise control of the PWM outputs. This extension is the high-resolution pulse width modulator (HRPWM)
and is described in the TMS320x2833x, 2823x High-Resolution Pulse Width Modulator (HRPWM)
Reference Guide (SPRUG02) . See the device-specific data manual to determine which ePWM instances
include this feature. Each ePWM module is indicated by a numerical value starting with 1. For example
ePWM1 is the first instance and ePWM3 is the 3rd instance in the system and ePWMx indicates any
instance.
The ePWM modules are chained together via a clock synchronization scheme that allows them to operate
as a single system when required. Additionally, this synchronization scheme can be extended to the
capture peripheral modules (eCAP). The number of modules is device-dependent and based on target
application needs. Modules can also operate stand-alone.
Each ePWM module supports the following features:
• Dedicated 16-bit time-base counter with period and frequency control
• Two PWM outputs (EPWMxA and EPWMxB) that can be used in the following configurations:
– Two independent PWM outputs with single-edge operation
– Two independent PWM outputs with dual-edge symmetric operation
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11
Introduction
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– One independent PWM output with dual-edge asymmetric operation
Asynchronous override control of PWM signals through software.
Programmable phase-control support for lag or lead operation relative to other ePWM modules.
Hardware-locked (synchronized) phase relationship on a cycle-by-cycle basis.
Dead-band generation with independent rising and falling edge delay control.
Programmable trip zone allocation of both cycle-by-cycle trip and one-shot trip on fault conditions.
A trip condition can force either high, low, or high-impedance state logic levels at PWM outputs.
All events can trigger both CPU interrupts and ADC start of conversion (SOC)
Programmable event prescaling minimizes CPU overhead on interrupts.
PWM chopping by high-frequency carrier signal, useful for pulse transformer gate drives.
Each ePWM module is connected to the input/output signals shown in Figure 1. The signals are described
in detail in subsequent sections.
12
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Figure 1. Multiple ePWM Modules
xSYNCI
SYNCI
EPWM1INT
EPWM1A
EPWM1SOC
ePWM1 module
EPWM1B
SYNCO
xSYNCO
To eCAP1
SYNCI
EPWM2INT
EPWM2SOC
PIE
EPWM2A
ePWM2 module
EPWM2B
GPIO
MUX
SYNCO
SYNCI
EPWMxINT
EPWMxSOC
EPWMxA
ePWMx module
EPWMxB
TZ1 to TZ6
SYNCO
xSOC
ADC
Peripheral
Frame 1
The order in which the ePWM modules are connected may differ from what is shown in Figure 1. See
Section 2.2.3.3 for the synchronization scheme for a particular device. Each ePWM module consists of
seven submodules and is connected within a system via the signals shown in Figure 2.
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Figure 2. Submodules and Signal Connections for an ePWM Module
EPWMxSYNCI
EPWMxSYNCO
ePWM module
Time-base (TB) module
Counter-compare (CC) module
PIE
EPWMxTZINT
EPWMxINT
Action-qualifier (AQ) module
Dead-band (DB) module
ADC
EPWMxSOCA
EPWMxSOCB
PWM-chopper (PC) module
TZ1 to TZ6
EPWMxA
EPWMxB
GPIO
MUX
Event-trigger (ET) module
Peripheral bus
Trip-zone (TZ) module
Figure 3 shows more internal details of a single ePWM module. The main signals used by the ePWM
module are:
• PWM output signals (EPWMxA and EPWMxB).
The PWM output signals are made available external to the device through the GPIO peripheral
described in the system control and interrupts guide for your device.
• Trip-zone signals (TZ1 to TZ6).
These input signals alert the ePWM module of fault conditions external to the ePWM module. Each
module on a device can be configured to either use or ignore any of the trip-zone signals. The TZ1 to
TZ6 trip-zone signals can be configured as asynchronous inputs through the GPIO peripheral.
• Time-base synchronization input (EPWMxSYNCI) and output (EPWMxSYNCO) signals.
The synchronization signals daisy chain the ePWM modules together. Each module can be configured
to either use or ignore its synchronization input. The clock synchronization input and output signal are
brought out to pins only for ePWM1 (ePWM module #1). The synchronization output for ePWM1
(EPWM1SYNCO) is also connected to the SYNCI of the first enhanced capture module (eCAP1).
• ADC start-of-conversion signals (EPWMxSOCA and EPWMxSOCB).
Each ePWM module has two ADC start of conversion signals (one for each sequencer). Any ePWM
module can trigger a start of conversion for either sequencer. Which event triggers the start of
conversion is configured in the Event-Trigger submodule of the ePWM.
• Peripheral Bus
The peripheral bus is 32-bits wide and allows both 16-bit and 32-bit writes to the ePWM register file.
14
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Figure 3. ePWM Submodules and Critical Internal Signal Interconnects
Time-base (TB)
Sync
in/out
select
MUX
TBPRD shadow (16)
TBPRD active (16)
S0
CTR_PRD
S1
TBCTL[SWFSYNC]
16
Counter
UP/DWN
(16 bit)
EPWMxSYNCO
EPWMxSYNCI
TBCTL[PHSEN]
TBCTL[SWFSYNC] (software
forced sync)
CTR = ZERO
TBCTR
active
(16)
CTR_Dir
16
TBPHS active (16)
CTR = PRD
Phase
control
CTR = ZERO
CTR = CMPA
CTR = CMPB
Counter compare (CC)
CTR_Dir
EPWMxINT
Event
trigger and
interrupt
(ET)
EPWMxSOCA
EPWMxSOCB
16
CTR = CMPA
16
Action
qualifier
(AQ)
CMPA active (16)
Dead
band
(DB)
CMPA shadow (16)
16
16
EPWMxA
PWM
chopper
(PC)
CTR = CMPB
CMPB active (16)
CMPB shadow (16)
Trip
zone
(TZ)
EPWMxB
EPWMxTZINT
TZ1 to TZ6
CTR=ZERO
Figure 3 also shows the key internal submodule interconnect signals. Each submodule is described in
detail in its respective section.
1.2
Register Mapping
The complete ePWM module control and status register set is grouped by submodule as shown in
Table 1. Each register set is duplicated for each instance of the ePWM module. The start address for each
ePWM register file instance on a device is specified in the appropriate data manual.
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Table 1. ePWM Module Control and Status Register Set Grouped by Submodule
Offset
(1)
Size
(x16)
Shadow
TBCTL
0x0000
1
No
Time-Base Control Register
TBSTS
0x0001
1
No
Time-Base Status Register
TBPHSHR
0x0002
1
No
Extension for HRPWM Phase Register
TBPHS
0x0003
1
No
Time-Base Phase Register
TBCTR
0x0004
1
No
Time-Base Counter Register
TBPRD
0x0005
1
Yes
Time-Base Period Register
CMPCTL
0x0007
1
No
Counter-Compare Control Register
CMPAHR
0x0008
1
Yes
Extension for HRPWM Counter-Compare A Register
CMPA
0x0009
1
Yes
Counter-Compare A Register
CMPB
0x000A
1
Yes
Counter-Compare B Register
AQCTLA
0x000B
1
No
Action-Qualifier Control Register for Output A (EPWMxA)
AQCTLB
0x000C
1
No
Action-Qualifier Control Register for Output B (EPWMxB)
AQSFRC
0x000D
1
No
Action-Qualifier Software Force Register
AQCSFRC
0x000E
1
Yes
Action-Qualifier Continuous S/W Force Register Set
DBCTL
0x000F
1
No
Dead-Band Generator Control Register
DBRED
0x0010
1
No
Dead-Band Generator Rising Edge Delay Count Register
DBFED
0x0011
1
No
Dead-Band Generator Falling Edge Delay Count Register
Name
EALLOW Description
Time-Base Submodule Registers
(2)
Counter-Compare Submodule Registers
(2)
Action-Qualifier Submodule Registers
Dead-Band Generator Submodule Registers
Trip-Zone Submodule Registers
TZSEL
0x0012
1
Yes
Trip-Zone Select Register
TZCTL
0x0014
1
Yes
Trip-Zone Control Register
TZEINT
0x0015
1
Yes
Trip-Zone Enable Interrupt Register
TZFLG
0x0016
1
TZCLR
0x0017
1
Yes
Trip-Zone Clear Register
(3)
TZFRC
0x0018
1
Yes
Trip-Zone Force Register
(3)
Trip-Zone Flag Register
(3)
(3)
(3)
Event-Trigger Submodule Registers
ETSEL
0x0019
1
Event-Trigger Selection Register
ETPS
0x001A
1
Event-Trigger Pre-Scale Register
ETFLG
0x001B
1
Event-Trigger Flag Register
ETCLR
0x001C
1
Event-Trigger Clear Register
ETFRC
0x001D
1
Event-Trigger Force Register
PCCTL
0x001E
1
PWM-Chopper Submodule Registers
PWM-Chopper Control Register
High-Resolution Pulse Width Modulator (HRPWM) Extension
Registers
HRCNFG
(1)
(2)
(3)
16
0x0020
1
Yes
HRPWM Configuration Register
(2) (3)
Locations not shown are reserved.
These registers are only available on ePWM instances that include the high-resolution PWM extension. Otherwise these
locations are reserved. These registers are described in the TMS320x2833x, 2823x High-Resolution Pulse Width Modulator
(HRPWM) Reference Guide (SPRUG02) . See the device specific data manual to determine which instances include the
HRPWM.
EALLOW protected registers as described in the specific device version of the System Control and Interrupts Reference Guide
listed in Related Documentation From Texas Instruments.
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2
ePWM Submodules
Seven submodules are included in every ePWM peripheral. Each of these submodules performs specific
tasks that can be configured by software.
2.1
Overview
Table 2 lists the seven key submodules together with a list of their main configuration parameters. For
example, if you need to adjust or control the duty cycle of a PWM waveform, then you should see the
counter-compare submodule in Section 2.3 for relevant details.
Table 2. Submodule Configuration Parameters
Submodule
Configuration Parameter or Option
Time-base (TB)
• Scale the time-base clock (TBCLK) relative to the system clock (SYSCLKOUT).
• Configure the PWM time-base counter (TBCTR) frequency or period.
• Set the mode for the time-base counter:
– count-up mode: used for asymmetric PWM
– count-down mode: used for asymmetric PWM
– count-up-and-down mode: used for symmetric PWM
• Configure the time-base phase relative to another ePWM module.
• Synchronize the time-base counter between modules through hardware or software.
• Configure the direction (up or down) of the time-base counter after a synchronization event.
• Configure how the time-base counter will behave when the device is halted by an emulator.
• Specify the source for the synchronization output of the ePWM module:
– Synchronization input signal
– Time-base counter equal to zero
– Time-base counter equal to counter-compare B (CMPB)
– No output synchronization signal generated.
Counter-compare (CC)
• Specify the PWM duty cycle for output EPWMxA and/or output EPWMxB
• Specify the time at which switching events occur on the EPWMxA or EPWMxB output
Action-qualifier (AQ)
• Specify the type of action taken when a time-base or counter-compare submodule event occurs:
– No action taken
– Output EPWMxA and/or EPWMxB switched high
– Output EPWMxA and/or EPWMxB switched low
– Output EPWMxA and/or EPWMxB toggled
• Force the PWM output state through software control
• Configure and control the PWM dead-band through software
Dead-band (DB)
•
•
•
•
Control of traditional complementary dead-band relationship between upper and lower switches
Specify the output rising-edge-delay value
Specify the output falling-edge delay value
Bypass the dead-band module entirely. In this case the PWM waveform is passed through
without modification.
PWM-chopper (PC)
•
•
•
•
Create a chopping (carrier) frequency.
Pulse width of the first pulse in the chopped pulse train.
Duty cycle of the second and subsequent pulses.
Bypass the PWM-chopper module entirely. In this case the PWM waveform is passed through
without modification.
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Table 2. Submodule Configuration Parameters (continued)
Submodule
Configuration Parameter or Option
Trip-zone (TZ)
• Configure the ePWM module to react to one, all, or none of the trip-zone pins .
• Specify the tripping action taken when a fault occurs:
– Force EPWMxA and/or EPWMxB high
– Force EPWMxA and/or EPWMxB low
– Force EPWMxA and/or EPWMxB to a high-impedance state
– Configure EPWMxA and/or EPWMxB to ignore any trip condition.
• Configure how often the ePWM will react to each trip-zone pins :
– One-shot
– Cycle-by-cycle
• Enable the trip-zone to initiate an interrupt.
• Bypass the trip-zone module entirely.
Event-trigger (ET)
• Enable the ePWM events that will trigger an interrupt.
• Enable ePWM events that will trigger an ADC start-of-conversion event.
• Specify the rate at which events cause triggers (every occurrence or every second or third
occurrence)
• Poll, set, or clear event flags
Code examples are provided in the remainder of this document that show how to implement various
ePWM module configurations. These examples use the constant definitions shown in Example 1. These
definitions are also used in the C2833x/2823x C/C++ Header Files and Peripheral Examples (SPRC530) .
Example 1. Constant Definitions Used in the Code Examples
// TBCTL (Time-Base Control)
// = = = = = = = = = = = = = = = = = =
// TBCTR MODE bits
#define TB_COUNT_UP 0x0
#define TB_COUNT_DOWN 0x1
#define TB_COUNT_UPDOWN 0x2
#define TB_FREEZE 0x3
// PHSEN bit
#define TB_DISABLE 0x0
#define TB_ENABLE 0x1
// PRDLD bit
#define TB_SHADOW 0x0
#define TB_IMMEDIATE 0x1
// SYNCOSEL bits
#define TB_SYNC_IN 0x0
#define TB_CTR_ZERO 0x1
#define TB_CTR_CMPB 0x2
#define TB_SYNC_DISABLE 0x3
// HSPCLKDIV and CLKDIV bits
#define TB_DIV1 0x0
#define TB_DIV2 0x1
#define TB_DIV4 0x2
// PHSDIR bit
#define TB_DOWN 0x0
#define TB_UP 0x1
// CMPCTL (Compare Control)
// = = = = = = = = = = = = = = = = = =
//
LOADAMODE and LOADBMODE bits
#define CC_CTR_ZERO 0x0
#define CC_CTR_PRD 0x1
#define CC_CTR_ZERO_PRD 0x2 #
define CC_LD_DISABLE 0x3
// SHDWAMODE and SHDWBMODE bits
#define CC_SHADOW 0x0
#define CC_IMMEDIATE 0x1
// AQCTLA and AQCTLB (Action-qualifier
// = = = = = = = = = = = = = = = = = =
// ZRO, PRD, CAU, CAD, CBU, CBD bits
18
= = = = = = = =
= = = = = = = =
Control)
= = = = = = = =
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Example 1. Constant Definitions Used in the Code Examples (continued)
#define AQ_NO_ACTION 0x0
#define AQ_CLEAR 0x1
#define AQ_SET 0x2
#define AQ_TOGGLE 0x3
// DBCTL (Dead-Band Control)
// = = = = = = = = = = = = = = = = = = =
// MODE bits
#define DB_DISABLE 0x0
#define DBA_ENABLE 0x1
#define DBB_ENABLE 0x2
#define DB_FULL_ENABLE 0x3
// POLSEL bits
#define DB_ACTV_HI 0x0
#define DB_ACTV_LOC 0x1
#define DB_ACTV_HIC 0x2
#define DB_ACTV_LO 0x3 // PCCTL (chopper
// = = = = = = = = = = = = = = = = = = =
// CHPEN bit
#define CHP_ENABLE 0x0
#define CHP_DISABLE 0x1
// CHPFREQ bits
#define CHP_DIV1 0x0
#define CHP_DIV2 0x1
#define CHP_DIV3 0x2
#define CHP_DIV4 0x3
#define CHP_DIV5 0x4
#define CHP_DIV6 0x5
#define CHP_DIV7 0x6
#define CHP_DIV8 0x7
// CHPDUTY bits
#define CHP1_8TH 0x0
#define CHP2_8TH 0x1
#define CHP3_8TH 0x2
#define CHP4_8TH 0x3
#define CHP5_8TH 0x4
#define CHP6_8TH 0x5 #
define CHP7_8TH 0x6
// TZSEL (Trip-zone Select)
// = = = = = = = = = = = = = = = = = = =
// CBCn and OSHTn bits
#define TZ_ENABLE 0x0
#define TZ_DISABLE 0x1
// TZCTL (Trip-zone Control)
// = = = = = = = = = = = = = = = = = = =
// TZA and TZB bits
#define TZ_HIZ 0x0
#define TZ_FORCE_HI 0x1
#define TZ_FORCE_LO 0x2
#define TZ_DISABLE 0x3
// ETSEL (Event-trigger Select)
// = = = = = = = = = = = = = = = = = = =
// INTSEL, SOCASEL, SOCBSEL bits
#define ET_CTR_ZERO 0x1
#define ET_CTR_PRD 0x2
#define ET_CTRU_CMPA 0x4
#define ET_CTRD_CMPA 0x5
#define ET_CTRU_CMPB 0x6
#define ET_CTRD_CMPB 0x7
// ETPS (Event-trigger Prescale)
// = = = = = = = = = = = = = = = = = = =
// INTPRD, SOCAPRD, SOCBPRD bits
#define ET_DISABLE 0x0
#define ET_1ST 0x1
#define ET_2ND 0x2
#define ET_3RD 0x3
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= = = = = = =
control)
= = = = = = =
= = = = = = =
= = = = = = =
= = = = = = =
= = = = = = =
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Time-Base (TB) Submodule
Each ePWM module has its own time-base submodule that determines all of the event timing for the
ePWM module. Built-in synchronization logic allows the time-base of multiple ePWM modules to work
together as a single system. Figure 4 illustrates the time-base module's place within the ePWM.
Figure 4. Time-Base Submodule Block Diagram
CTR = PRD
EPWMxINT
Event
Trigger
EPWMxSOCA
and
Interrupt
CTR = 0
EPWMxSYNCI
EPWMxSYNCO
CTR = PRD
Time-Base
(TB)
Action
Qualifier
(AQ)
CTR = CMPA
CTR = CMPB
(ET)
CTR_Dir
CTR = 0
ADC
EPWMxSOCB
CTR_Dir
EPWMxA
EPWMxA
Dead
Band
(DB)
CTR = CMPA
Counter
Compare
(CC)
PIE
PWMchopper
(PC)
Trip
Zone
(TZ)
GPIO
EPWMxB
CTR = CMPB
EPWMxB
MUX
CTR = 0
EPWMxTZINT
TZ1 to TZ6
PIE
2.2.1
Purpose of the Time-Base Submodule
You can configure the time-base submodule for the following:
• Specify the ePWM time-base counter (TBCTR) frequency or period to control how often events occur.
• Manage time-base synchronization with other ePWM modules.
• Maintain a phase relationship with other ePWM modules.
• Set the time-base counter to count-up, count-down, or count-up-and-down mode.
• Generate the following events:
– CTR = PRD: Time-base counter equal to the specified period (TBCTR = TBPRD) .
– CTR = Zero: Time-base counter equal to zero (TBCTR = 0x0000).
• Configure the rate of the time-base clock; a prescaled version of the CPU system clock
(SYSCLKOUT). This allows the time-base counter to increment/decrement at a slower rate.
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2.2.2
Controlling and Monitoring the Time-base Submodule
Table 3 shows the registers used to control and monitor the time-base submodule.
Table 3. Time-Base Submodule Registers
Register
Address offset
Shadowed
TBCTL
0x0000
No
Time-Base Control Register
TBSTS
0x0001
No
Time-Base Status Register
TBPHSHR
0x0002
No
HRPWM Extension Phase Register
TBPHS
0x0003
No
Time-Base Phase Register
TBCTR
0x0004
No
Time-Base Counter Register
TBPRD
0x0005
Yes
Time-Base Period Register
(1)
Description
(1)
This register is available only on ePWM instances that include the high-resolution extension (HRPWM). On ePWM modules that
do not include the HRPWM, this location is reserved. This register is described in the device-specific High-Resolution Pulse
Width Modulator (HRPWM) Reference Guide. See the device specific data manual to determine which ePWM instances include
this feature.
The block diagram in Figure 5 shows the critical signals and registers of the time-base submodule.
Table 4 provides descriptions of the key signals associated with the time-base submodule.
Figure 5. Time-Base Submodule Signals and Registers
TBPRD
Period Shadow
TBCTL[PRDLD]
TBPRD
Period Active
TBCTL[SWFSYNC]
16
CTR = PRD
TBCTR[15:0]
EPWMxSYNCI
16
CTR = Zero
CTR_dir
CTR_max
TBCLK
Reset
Zero Counter
Mode
Dir UP/DOWN
Load
Max
TBCTL[CTRMODE]
CTR = Zero
clk
TBCTR
Counter Active Reg
TBCTL[PHSEN]
CTR = CMPB
X
Disable
Sync
Out
Select
EPWMxSYNCO
16
TBPHS
Phase Active Reg
SYSCLKOUT
Clock
Prescale
TBCTL[SYNCOSEL]
TBCLK
TBCTL[HSPCLKDIV]
TBCTL[CLKDIV]
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Table 4. Key Time-Base Signals
Signal
Description
EPWMxSYNCI
Time-base synchronization input.
Input pulse used to synchronize the time-base counter with the counter of ePWM module earlier in the
synchronization chain. An ePWM peripheral can be configured to use or ignore this signal. For the first ePWM
module (EPWM1) this signal comes from a device pin. For subsequent ePWM modules this signal is passed
from another ePWM peripheral. For example, EPWM2SYNCI is generated by the ePWM1 peripheral,
EPWM3SYNCI is generated by ePWM2 and so forth. See Section 2.2.3.3 for information on the
synchronization order of a particular device.
EPWMxSYNCO
Time-base synchronization output.
This output pulse is used to synchronize the counter of an ePWM module later in the synchronization chain.
The ePWM module generates this signal from one of three event sources:
1.
2.
3.
CTR = PRD
EPWMxSYNCI (Synchronization input pulse)
CTR = Zero: The time-base counter equal to zero (TBCTR = 0x0000).
CTR = CMPB: The time-base counter equal to the counter-compare B (TBCTR = CMPB) register.
Time-base counter equal to the specified period.
This signal is generated whenever the counter value is equal to the active period register value. That is when
TBCTR = TBPRD.
CTR = Zero
Time-base counter equal to zero
This signal is generated whenever the counter value is zero. That is when TBCTR equals 0x0000.
CTR = CMPB
Time-base counter equal to active counter-compare B register (TBCTR = CMPB).
This event is generated by the counter-compare submodule and used by the synchronization out logic
CTR_dir
Time-base counter direction.
Indicates the current direction of the ePWM's time-base counter. This signal is high when the counter is
increasing and low when it is decreasing.
CTR_max
Time-base counter equal max value. (TBCTR = 0xFFFF)
Generated event when the TBCTR value reaches its maximum value. This signal is only used only as a status
bit
TBCLK
Time-base clock.
This is a prescaled version of the system clock (SYSCLKOUT) and is used by all submodules within the
ePWM. This clock determines the rate at which time-base counter increments or decrements.
2.2.3
Calculating PWM Period and Frequency
The frequency of PWM events is controlled by the time-base period (TBPRD) register and the mode of the
time-base counter. Figure 6 shows the period (Tpwm) and frequency (Fpwm) relationships for the up-count,
down-count, and up-down-count time-base counter modes when when the period is set to 4 (TBPRD = 4).
The time increment for each step is defined by the time-base clock (TBCLK) which is a prescaled version
of the system clock (SYSCLKOUT).
The time-base counter has three modes of operation selected by the time-base control register (TBCTL):
• Up-Down-Count Mode:
In up-down-count mode, the time-base counter starts from zero and increments until the period
(TBPRD) value is reached. When the period value is reached, the time-base counter then decrements
until it reaches zero. At this point the counter repeats the pattern and begins to increment.
• Up-Count Mode:
In this mode, the time-base counter starts from zero and increments until it reaches the value in the
period register (TBPRD). When the period value is reached, the time-base counter resets to zero and
begins to increment once again.
• Down-Count Mode:
In down-count mode, the time-base counter starts from the period (TBPRD) value and decrements until
it reaches zero. When it reaches zero, the time-base counter is reset to the period value and it begins
to decrement once again.
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Figure 6. Time-Base Frequency and Period
TPWM
4
PRD
4
4
3
3
2
3
2
1
2
1
0
Z 1
0
0
For Up Count and Down Count
TPWM
4
4
3
TPWM = (TBPRD + 1) x TTBCLK
FPWM = 1/ (TPWM)
PRD
4
3
2
3
2
1
2
1
0
1 Z
0
0
TPWM
TPWM
4
3
3
1
3
2
2
1
0
2.2.3.1
3
2
2
CTR_dir
1
1
0
0
Up
For Up and Down Count
TPWM = 2 x TBPRD x TTBCLK
FPWM = 1 / (TPWM)
4
Down
Up
Down
Time-Base Period Shadow Register
The time-base period register (TBPRD) has a shadow register. Shadowing allows the register update to
be synchronized with the hardware. The following definitions are used to describe all shadow registers in
the ePWM module:
• Active Register
The active register controls the hardware and is responsible for actions that the hardware causes or
invokes.
• Shadow Register
The shadow register buffers or provides a temporary holding location for the active register. It has no
direct effect on any control hardware. At a strategic point in time the shadow register's content is
transferred to the active register. This prevents corruption or spurious operation due to the register
being asynchronously modified by software.
The memory address of the shadow period register is the same as the active register. Which register is
written to or read from is determined by the TBCTL[PRDLD] bit. This bit enables and disables the TBPRD
shadow register as follows:
•
•
Time-Base Period Shadow Mode:
The TBPRD shadow register is enabled when TBCTL[PRDLD] = 0. Reads from and writes to the
TBPRD memory address go to the shadow register. The shadow register contents are transferred to
the active register (TBPRD (Active) ← TBPRD (shadow)) when the time-base counter equals zero
(TBCTR = 0x0000). By default the TBPRD shadow register is enabled.
Time-Base Period Immediate Load Mode:
If immediate load mode is selected (TBCTL[PRDLD] = 1), then a read from or a write to the TBPRD
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memory address goes directly to the active register.
2.2.3.2
Time-Base Clock Synchronization
The TBCLKSYNC bit in the peripheral clock enable registers allows all users to globally synchronize all
enabled ePWM modules to the time-base clock (TBCLK). When set, all enabled ePWM module clocks are
started with the first rising edge of TBCLK aligned. For perfectly synchronized TBCLKs, the prescalers for
each ePWM module must be set identically.
The proper procedure for enabling ePWM clocks is as follows:
1. Enable ePWM module clocks in the PCLKCRx register
2. Set TBCLKSYNC= 0
3. Configure ePWM modules
4. Set TBCLKSYNC=1
2.2.3.3
Time-Base Counter Synchronization
A time-base synchronization scheme connects all of the ePWM modules on a device. Each ePWM
module has a synchronization input (EPWMxSYNCI) and a synchronization output (EPWMxSYNCO). The
input synchronization for the first instance (ePWM1) comes from an external pin. The possible
synchronization connections for the remaining ePWM modules are shown in Figure 7, Figure 8, and
Figure 9.
Scheme 1 shown in Figure 7 applies to the 280x, 2801x, 2802x, and 2803x devices. Scheme 1 also
applies to the 2804x devices when the ePWM pinout is configured for 280x compatible mode
(GPAMCFG[EPWMMODE] = 0).
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Figure 7. Time-Base Counter Synchronization Scheme 1
EPWM1SYNCI
ePWM1
GPIO
MUX
EPWM1SYNCO
SYNCI
eCAP1
EPWM2SYNCI
ePWM2
EPWM2SYNCO
EPWM3SYNCI
ePWM3
EPWM3SYNCO
EPWMxSYNCI
ePWMx
EPWMxSYNCO
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Scheme 2 shown in Figure 8 is used by the 2804x devices when the ePWM pinout is configured for
A-channel only mode (GPAMCFG[EPWMMODE] = 3). If the 2804x ePWM pinout is configured for 280x
compatible mode (GPAMCFG[EPWMMODE] = 0), then Scheme 1 is used.
Figure 8. Time-Base Counter Synchronization Scheme 2
EPWM1SYNCI
ePWM1
GPIO
EPWM1SYNCO
MUX
SYNCI
eCAP1
26
EPWM13SYNCI
EPWM9SYNCI
EPWM5SYNCI
EPWM2SYNCI
ePWM13
ePWM9
ePWM5
ePWM2
EPWM13SYnCO
EPWM9SYNCO
EPWM5SYNCO
EPWM2SYNCO
EPWM14SYNCI
EPWM10SYNCI
EPWM6SYNCI
EPWM3SYNCI
ePWM14
ePWM10
ePWM6
ePWM3
EPWM14SYNCO
EPWM10SYNCO
EPWM36YNCO
EPWM3SYNCO
EPWM15SYNCI
EPWM11SYNCI
EPWM7SYNCI
EPWM4SYNCI
ePWM15
ePWM11
ePWM7
ePWM4
EPWM15SYNCO
EPWM11SYNCO
EPWM7SYNCO
EPWM4SYNCO
EPWM16SYNCI
EPWM12SYNCI
EPWM8SYNCI
ePWM16
ePWM12
ePWM8
EPWM16SYNCO
EPWM12SYNCO
EPWM8SYNCO
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Scheme 3, shown in Figure 9, is used by all other devices.
Figure 9. Time-Base Counter Synchronization Scheme 3
eCAP4
EPWM1SYNCI
ePWM1
GPIO
MUX
EPWM1SYNCO
SYNCI
eCAP1
EPWM7SYNCI
EPWM4SYNCI
EPWM2SYNCI
ePWM7
ePWM4
ePWM2
EPWM7SYNCO
EPWM4SYNCO
EPWM2SYNCO
EPWM8SYNCI
EPWM5SYNCI
EPWM3SYNCI
ePWM8
ePWM5
ePWM3
EPWM8SYNCO
EPWM5SYNCO
EPWM3SYNCO
EPWM9SYNCI
EPWM6SYNCI
ePWM9
ePWM6
NOTE: All modules shown in the synchronization schemes may not be available on all devices.
Please refer to the device specific data manual to determine which modules are available on
a particular device.
Each ePWM module can be configured to use or ignore the synchronization input. If the TBCTL[PHSEN]
bit is set, then the time-base counter (TBCTR) of the ePWM module will be automatically loaded with the
phase register (TBPHS) contents when one of the following conditions occur:
• EPWMxSYNCI: Synchronization Input Pulse:
The value of the phase register is loaded into the counter register when an input synchronization pulse
is detected (TBPHS → TBCTR). This operation occurs on the next valid time-base clock (TBCLK)
edge.
The delay from internal master module to slave modules is given by:
– if ( TBCLK = SYSCLKOUT): 2 x SYSCLKOUT
– if ( TBCLK != SYSCLKOUT):1 TBCLK
• Software Forced Synchronization Pulse:
Writing a 1 to the TBCTL[SWFSYNC] control bit invokes a software forced synchronization. This pulse
is ORed with the synchronization input signal, and therefore has the same effect as a pulse on
EPWMxSYNCI.
• This feature enables the ePWM module to be automatically synchronized to the time base of another
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ePWM module. Lead or lag phase control can be added to the waveforms generated by different
ePWM modules to synchronize them. In up-down-count mode, the TBCTL[PSHDIR] bit configures the
direction of the time-base counter immediately after a synchronization event. The new direction is
independent of the direction prior to the synchronization event. The PHSDIR bit is ignored in count-up
or count-down modes. See Figure 10 through Figure 13 for examples.
Clearing the TBCTL[PHSEN] bit configures the ePWM to ignore the synchronization input pulse. The
synchronization pulse can still be allowed to flow-through to the EPWMxSYNCO and be used to
synchronize other ePWM modules. In this way, you can set up a master time-base (for example, ePWM1)
and downstream modules (ePWM2 - ePWMx) may elect to run in synchronization with the master. See
the Application to Power Topologies Section 3 for more details on synchronization strategies.
2.2.4
Phase Locking the Time-Base Clocks of Multiple ePWM Modules
The TBCLKSYNC bit can be used to globally synchronize the time-base clocks of all enabled ePWM
modules on a device. This bit is part of the device's clock enable registers and is described in the specific
device version of the System Control and Interrupts Reference Guide listed in Related Documentation
From Texas Instruments. When TBCLKSYNC = 0, the time-base clock of all ePWM modules is stopped
(default). When TBCLKSYNC = 1, all ePWM time-base clocks are started with the rising edge of TBCLK
aligned. For perfectly synchronized TBCLKs, the prescaler bits in the TBCTL register of each ePWM
module must be set identically. The proper procedure for enabling the ePWM clocks is as follows:
1. Enable the individual ePWM module clocks. This is described in the specific device version of the
System Control and Interrupts Reference Guide listed in Related Documentation From Texas
Instruments.
2. Set TBCLKSYNC = 0. This will stop the time-base clock within any enabled ePWM module.
3. Configure the prescaler values and desired ePWM modes.
4. Set TBCLKSYNC = 1.
2.2.5
Time-base Counter Modes and Timing Waveforms
The time-base counter operates in one of four modes:
• Up-count mode which is asymmetrical.
• Down-count mode which is asymmetrical.
• Up-down-count which is symmetrical
• Frozen where the time-base counter is held constant at the current value
To illustrate the operation of the first three modes, the following timing diagrams show when events are
generated and how the time-base responds to an EPWMxSYNCI signal.
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Figure 10. Time-Base Up-Count Mode Waveforms
TBCTR[15:0]
0xFFFF
TBPRD
(value)
TBPHS
(value)
0000
EPWMxSYNCI
CTR_dir
CTR = zero
CTR = PRD
CNT_max
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Figure 11. Time-Base Down-Count Mode Waveforms
TBCTR[15:0]
0xFFFF
TBPRD
(value)
TBPHS
(value)
0x000
EPWMxSYNCI
CTR_dir
CTR = zero
CTR = PRD
CNT_max
Figure 12. Time-Base Up-Down-Count Waveforms, TBCTL[PHSDIR = 0] Count Down On Synchronization
Event
TBCTR[15:0]
0xFFFF
TBPRD
(value)
TBPHS
(value)
0x0000
EPWMxSYNCI
UP
UP
UP
UP
CTR_dir
DOWN
DOWN
DOWN
CTR = zero
CTR = PRD
CNT_max
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Figure 13. Time-Base Up-Down Count Waveforms, TBCTL[PHSDIR = 1] Count Up On Synchronization
Event
TBCTR[15:0]
0xFFFF
TBPRD (value)
TBPHS (value)
0x0000
EPWMxSYNCI
UP
UP
UP
CTR_dir
DOWN
DOWN
DOWN
CTR = zero
CTR = PRD
CNT_max
2.3
Counter-Compare (CC) Submodule
Figure 14 illustrates the counter-compare submodule within the ePWM.
Figure 14. Counter-Compare Submodule
CTR = PRD
CTR = 0
EPWMxSYNCI
EPWMxSYNCO
CTR = PRD
Time-Base
(TB)
Action
Qualifier
(AQ)
CTR = CMPA
CTR = CMPB
CTR_Dir
CTR = 0
EPWMxINT
Event
Trigger
EPWMxSOCA
and
Interrupt
(ET)
ADC
EPWMxSOCB
CTR_Dir
EPWMxA
EPWMxA
Dead
Band
(DB)
CTR = CMPA
Counter
Compare
(CC)
PIE
PWMchopper
(PC)
Trip
Zone
(TZ)
GPIO
EPWMxB
CTR = CMPB
EPWMxB
MUX
CTR = 0
EPWMxTZINT
TZ1 to TZ6
PIE
Figure 15 shows the basic structure of the counter-compare submodule.
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Purpose of the Counter-Compare Submodule
The counter-compare submodule takes as input the time-base counter value. This value is continuously
compared to the counter-compare A (CMPA) and counter-compare B (CMPB) registers. When the
time-base counter is equal to one of the compare registers, the counter-compare unit generates an
appropriate event.
The counter-compare:
• Generates events based on programmable time stamps using the CMPA and CMPB registers
– CTR = CMPA: Time-base counter equals counter-compare A register (TBCTR = CMPA).
– CTR = CMPB: Time-base counter equals counter-compare B register (TBCTR = CMPB)
• Controls the PWM duty cycle if the action-qualifier submodule is configured appropriately
• Shadows new compare values to prevent corruption or glitches during the active PWM cycle
2.3.2
Controlling and Monitoring the Counter-Compare Submodule
The counter-compare submodule operation is controlled and monitored by the registers shown in Table 5:
Table 5. Counter-Compare Submodule Registers
Address Offset
Shadowed
CMPCTL
Register Name
0x0007
No
Counter-Compare Control Register.
CMPAHR
0x0008
Yes
HRPWM Counter-Compare A Extension Register
CMPA
0x0009
Yes
Counter-Compare A Register
CMPB
0x000A
Yes
Counter-Compare B Register
(1)
Description
(1)
This register is available only on ePWM modules with the high-resolution extension (HRPWM). On ePWM modules that do not
include the HRPWM this location is reserved. This register is described in the device-specific High-Resolution Pulse Width
Modulator (HRPWM) Reference Guide. Refer to the device specific data manual to determine which ePWM instances include
this feature.
Figure 15. Detailed View of the Counter-Compare Submodule
Time
Base
(TB)
Module
TBCTR[15:0] 16
CTR = CMPA
CMPA[15:0]
CTR = PRD
CTR =0
Shadow
load
CMPCTL[LOADAMODE]
16
CMPA
Compare A Active Reg.
CMPA
Compare A Shadow Reg.
TBCTR[15:0]
Digital
comparator A
CMPCTL
[SHDWAFULL]
CMPCTL
[SHDWAMODE]
Action
Qualifier
(AQ)
Module
16
CTR = CMPB
CMPB[15:0] 16
CTR = PRD
CTR = 0
Shadow
load
CMPB
Compare B Active Reg.
CMPB
Compare B Shadow Reg.
Digital
comparator B
CMPCTL[SHDWBFULL]
CMPCTL[SHDWBMODE]
CMPCTL[LOADBMODE]
The key signals associated with the counter-compare submodule are described in Table 6.
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Table 6. Counter-Compare Submodule Key Signals
2.3.3
Signal
Description of Event
Registers Compared
CTR = CMPA
Time-base counter equal to the active counter-compare A value
TBCTR = CMPA
CTR = CMPB
Time-base counter equal to the active counter-compare B value
TBCTR = CMPB
CTR = PRD
Time-base counter equal to the active period.
Used to load active counter-compare A and B registers from the
shadow register
TBCTR = TBPRD
CTR = ZERO
Time-base counter equal to zero.
Used to load active counter-compare A and B registers from the
shadow register
TBCTR = 0x0000
Operational Highlights for the Counter-Compare Submodule
The counter-compare submodule is responsible for generating two independent compare events based on
two compare registers:
1. CTR = CMPA: Time-base counter equal to counter-compare A register (TBCTR = CMPA).
2. CTR = CMPB: Time-base counter equal to counter-compare B register (TBCTR = CMPB).
For up-count or down-count mode, each event occurs only once per cycle. For up-down-count mode each
event occurs twice per cycle if the compare value is between 0x0000-TBPRD and once per cycle if the
compare value is equal to 0x0000 or equal to TBPRD. These events are fed into the action-qualifier
submodule where they are qualified by the counter direction and converted into actions if enabled. Refer
to Section 2.4.1 for more details.
The counter-compare registers CMPA and CMPB each have an associated shadow register. Shadowing
provides a way to keep updates to the registers synchronized with the hardware. When shadowing is
used, updates to the active registers only occur at strategic points. This prevents corruption or spurious
operation due to the register being asynchronously modified by software. The memory address of the
active register and the shadow register is identical. Which register is written to or read from is determined
by the CMPCTL[SHDWAMODE] and CMPCTL[SHDWBMODE] bits. These bits enable and disable the
CMPA shadow register and CMPB shadow register respectively. The behavior of the two load modes is
described below:
Shadow Mode:
The shadow mode for the CMPA is enabled by clearing the CMPCTL[SHDWAMODE] bit and the shadow
register for CMPB is enabled by clearing the CMPCTL[SHDWBMODE] bit. Shadow mode is enabled by
default for both CMPA and CMPB.
If the shadow register is enabled then the content of the shadow register is transferred to the active
register on one of the following events as specified by the CMPCTL[LOADAMODE] and
CMPCTL[LOADBMODE] register bits:
• CTR = PRD: Time-base counter equal to the period (TBCTR = TBPRD).
• CTR = Zero: Time-base counter equal to zero (TBCTR = 0x0000)
• Both CTR = PRD and CTR = Zero
Only the active register contents are used by the counter-compare submodule to generate events to be
sent to the action-qualifier.
Immediate Load Mode:
If immediate load mode is selected (i.e., TBCTL[SHADWAMODE] = 1 or TBCTL[SHADWBMODE] = 1),
then a read from or a write to the register will go directly to the active register.
2.3.4
Count Mode Timing Waveforms
The counter-compare module can generate compare events in all three count modes:
• Up-count mode: used to generate an asymmetrical PWM waveform.
• Down-count mode: used to generate an asymmetrical PWM waveform.
• Up-down-count mode: used to generate a symmetrical PWM waveform.
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To best illustrate the operation of the first three modes, the timing diagrams in Figure 16 through Figure 19
show when events are generated and how the EPWMxSYNCI signal interacts.
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Figure 16. Counter-Compare Event Waveforms in Up-Count Mode
TBCTR[15:0]
0xFFFF
TBPRD
(value)
CMPA
(value)
CMPB
(value)
TBPHS
(value)
0x0000
EPWMxSYNCI
CTR = CMPA
CTR = CMPB
NOTE: An EPWMxSYNCI external synchronization event can cause a discontinuity in the TBCTR count
sequence. This can lead to a compare event being skipped. This skipping is considered normal operation
and must be taken into account.
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Figure 17. Counter-Compare Events in Down-Count Mode
TBCTR[15:0]
0xFFFF
TBPRD
(value)
CMPA
(value)
CMPB
(value)
TBPHS
(value)
0x0000
EPWMxSYNCI
CTR = CMPA
CTR = CMPB
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Figure 18. Counter-Compare Events In Up-Down-Count Mode, TBCTL[PHSDIR = 0] Count Down On
Synchronization Event
TBCTR[15:0]
0xFFFF
TBPRD (value)
CMPA (value)
CMPB (value)
TBPHS (value)
0x0000
EPWMxSYNCI
CTR = CMPB
CTR = CMPA
Figure 19. Counter-Compare Events In Up-Down-Count Mode, TBCTL[PHSDIR = 1] Count Up On
Synchronization Event
TBCTR[15:0]
0xFFFF
TBPRD
(value)
CMPA
(value)
CMPB
(value)
TBPHS
(value)
0x0000
EPWMxSYNCI
CTR = CMPB
CTR = CMPA
2.4
Action-Qualifier (AQ) Submodule
Figure 20 shows the action-qualifier (AQ) submodule (see shaded block) in the ePWM system.
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Figure 20. Action-Qualifier Submodule
CTR = PRD
EPWMxINT
Event
Trigger
EPWMxSOCA
and
Interrupt
CTR = 0
EPWMxSYNCI
EPWMxSYNCO
CTR = PRD
Time-Base
(TB)
Action
Qualifier
(AQ)
CTR = CMPA
CTR = CMPB
(ET)
CTR_Dir
CTR = 0
ADC
EPWMxSOCB
CTR_Dir
EPWMxA
EPWMxA
Dead
Band
(DB)
CTR = CMPA
Counter
Compare
(CC)
PIE
PWMchopper
(PC)
Trip
Zone
(TZ)
GPIO
EPWMxB
CTR = CMPB
EPWMxB
MUX
CTR = 0
TZ1 to TZ6
EPWMxTZINT
PIE
The action-qualifier submodule has the most important role in waveform construction and PWM
generation. It decides which events are converted into various action types, thereby producing the
required switched waveforms at the EPWMxA and EPWMxB outputs.
2.4.1
Purpose of the Action-Qualifier Submodule
The action-qualifier submodule is responsible for the following:
• Qualifying and generating actions (set, clear, toggle) based on the following events:
– CTR = PRD: Time-base counter equal to the period (TBCTR = TBPRD).
– CTR = Zero: Time-base counter equal to zero (TBCTR = 0x0000)
– CTR = CMPA: Time-base counter equal to the counter-compare A register (TBCTR = CMPA)
– CTR = CMPB: Time-base counter equal to the counter-compare B register (TBCTR = CMPB)
• Managing priority when these events occur concurrently
• Providing independent control of events when the time-base counter is increasing and when it is
decreasing. .
2.4.2
Action-Qualifier Submodule Control and Status Register Definitions
The action-qualifier submodule operation is controlled and monitored via the registers in Table 7.
Table 7. Action-Qualifier Submodule Registers
Register
Name
38
Address offset
Shadowed
Description
AQCTLA
0x000B
No
Action-Qualifier Control Register For Output A (EPWMxA)
AQCTLB
0x000C
No
Action-Qualifier Control Register For Output B (EPWMxB)
AQSFRC
0x000D
No
Action-Qualifier Software Force Register
AQCSFRC
0x000E
Yes
Action-Qualifier Continuous Software Force
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The action-qualifier submodule is based on event-driven logic. It can be thought of as a programmable
cross switch with events at the input and actions at the output, all of which are software controlled via the
set of registers shown in Table 7.
Figure 21. Action-Qualifier Submodule Inputs and Outputs
Action-qualifier (AQ) Module
TBCLK
EPWMA
AQCTLA[15:0]
Action-qualifier control A
CTR = PRD
AQCTLB[15:0]
Action-qualifier control B
CTR = Zero
CTR = CMPA
AQSFRC[15:0]
Action-qualifier S/W force
CTR = CMPB
EPWMB
AQCSFRC[3:0] (shadow)
continuous S/W force
CTR_dir
AQCSFRC[3:0] (active)
continuous S/W force
For convenience, the possible input events are summarized again in Table 8.
Table 8. Action-Qualifier Submodule Possible Input Events
Signal
Description
Registers Compared
CTR = PRD
Time-base counter equal to the period value
TBCTR = TBPRD
CTR = Zero
Time-base counter equal to zero
TBCTR = 0x0000
CTR = CMPA
Time-base counter equal to the counter-compare A
TBCTR = CMPA
CTR = CMPB
Time-base counter equal to the counter-compare B
TBCTR = CMPB
Software forced event
Asynchronous event initiated by software
The software forced action is a useful asynchronous event. This control is handled by registers AQSFRC
and AQCSFRC.
The action-qualifier submodule controls how the two outputs EPWMxA and EPWMxB behave when a
particular event occurs. The event inputs to the action-qualifier submodule are further qualified by the
counter direction (up or down). This allows for independent action on outputs on both the count-up and
count-down phases.
The possible actions imposed on outputs EPWMxA and EPWMxB are:
• Set High:
Set output EPWMxA or EPWMxB to a high level.
• Clear Low:
Set output EPWMxA or EPWMxB to a low level.
• Toggle:
If EPWMxA or EPWMxB is currently pulled high, then pull the output low. If EPWMxA or EPWMxB is
currently pulled low, then pull the output high.
• Do Nothing:
Keep outputs EPWMxA and EPWMxB at same level as currently set. Although the "Do Nothing" option
prevents an event from causing an action on the EPWMxA and EPWMxB outputs, this event can still
trigger interrupts and ADC start of conversion. See the Event-trigger Submodule description in
Section 2.8 for details.
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Actions are specified independently for either output (EPWMxA or EPWMxB). Any or all events can be
configured to generate actions on a given output. For example, both CTR = CMPA and CTR = CMPB can
operate on output EPWMxA. All qualifier actions are configured via the control registers found at the end
of this section.
For clarity, the drawings in this document use a set of symbolic actions. These symbols are summarized in
Figure 22. Each symbol represents an action as a marker in time. Some actions are fixed in time (zero
and period) while the CMPA and CMPB actions are moveable and their time positions are programmed
via the counter-compare A and B registers, respectively. To turn off or disable an action, use the "Do
Nothing option"; it is the default at reset.
Figure 22. Possible Action-Qualifier Actions for EPWMxA and EPWMxB Outputs
TB Counter equals:
Actions
S/W
force
Zero
Comp
A
Comp
B
Period
SW
Z
CA
CB
P
SW
Z
CA
CB
P
SW
Z
CA
CB
P
Do Nothing
Clear Low
Set High
SW
T
40
Z
T
CA
T
CB
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2.4.3
Action-Qualifier Event Priority
It is possible for the ePWM action qualifier to receive more than one event at the same time. In this case
events are assigned a priority by the hardware. The general rule is events occurring later in time have a
higher priority and software forced events always have the highest priority. The event priority levels for
up-down-count mode are shown in Table 9. A priority level of 1 is the highest priority and level 7 is the
lowest. The priority changes slightly depending on the direction of TBCTR.
Table 9. Action-Qualifier Event Priority for Up-Down-Count Mode
Priority Level
1 (Highest)
Event If TBCTR is Incrementing
TBCTR = Zero up to TBCTR = TBPRD
Event If TBCTR is Decrementing
TBCTR = TBPRD down to TBCTR = 1
Software forced event
Software forced event
2
Counter equals CMPB on up-count (CBU)
Counter equals CMPB on down-count (CBD)
3
Counter equals CMPA on up-count (CAU)
Counter equals CMPA on down-count (CAD)
4
Counter equals zero
Counter equals period (TBPRD)
5
Counter equals CMPB on down-count (CBD)
Counter equals CMPB on up-count (CBU)
6 (Lowest)
Counter equals CMPA on down-count (CAD)
Counter equals CMPA on up-count (CBU)
Table 10 shows the action-qualifier priority for up-count mode. In this case, the counter direction is always
defined as up and thus down-count events will never be taken.
Table 10. Action-Qualifier Event Priority for Up-Count Mode
Priority Level
1 (Highest)
Event
Software forced event
2
Counter equal to period (TBPRD)
3
Counter equal to CMPB on up-count (CBU)
4
Counter equal to CMPA on up-count (CAU)
5 (Lowest)
Counter equal to Zero
Table 11 shows the action-qualifier priority for down-count mode. In this case, the counter direction is
always defined as down and thus up-count events will never be taken.
Table 11. Action-Qualifier Event Priority for Down-Count Mode
Priority Level
Event
1 (Highest)
Software forced event
2
Counter equal to Zero
3
Counter equal to CMPB on down-count (CBD)
4
Counter equal to CMPA on down-count (CAD)
5 (Lowest)
Counter equal to period (TBPRD)
It is possible to set the compare value greater than the period. In this case the action will take place as
shown in Table 12.
Table 12. Behavior if CMPA/CMPB is Greater than the Period
Counter Mode
Compare on Up-Count Event
CAD/CBD
Compare on Down-Count Event
CAD/CBD
Up-Count Mode
If CMPA/CMPB ≤ TBPRD period, then the event
occurs on a compare match (TBCTR=CMPA or
CMPB).
Never occurs.
If CMPA/CMPB > TBPRD, then the event will not
occur.
Down-Count Mode Never occurs.
If CMPA/CMPB < TBPRD, the event will occur on a
compare match (TBCTR=CMPA or CMPB).
If CMPA/CMPB ≥ TBPRD, the event will occur on a
period match (TBCTR=TBPRD).
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Table 12. Behavior if CMPA/CMPB is Greater than the Period (continued)
2.4.4
Counter Mode
Compare on Up-Count Event
CAD/CBD
Compare on Down-Count Event
CAD/CBD
Up-Down-Count
Mode
If CMPA/CMPB < TBPRD and the counter is
incrementing, the event occurs on a compare match
(TBCTR=CMPA or CMPB).
If CMPA/CMPB < TBPRD and the counter is
decrementing, the event occurs on a compare match
(TBCTR=CMPA or CMPB).
If CMPA/CMPB is ≥ TBPRD, the event will occur on a
period match (TBCTR = TBPRD).
If CMPA/CMPB ≥ TBPRD, the event occurs on a
period match (TBCTR=TBPRD).
Waveforms for Common Configurations
NOTE:
The waveforms in this document show the ePWMs behavior for a static compare register
value. In a running system, the active compare registers (CMPA and CMPB) are typically
updated from their respective shadow registers once every period. The user specifies when
the update will take place; either when the time-base counter reaches zero or when the
time-base counter reaches period. There are some cases when the action based on the new
value can be delayed by one period or the action based on the old value can take effect for
an extra period. Some PWM configurations avoid this situation. These include, but are not
limited to, the following:
Use up-down-count mode to generate a symmetric PWM:
• If you load CMPA/CMPB on zero, then use CMPA/CMPB values greater
than or equal to 1.
• If you load CMPA/CMPB on period, then use CMPA/CMPB values less than
or equal to TBPRD-1.
This means there will always be a pulse of at least one TBCLK cycle in a
PWM period which, when very short, tend to be ignored by the system.
Use up-down-count mode to generate an asymmetric PWM:
• To achieve 50%-0% asymmetric PWM use the following configuration: Load
CMPA/CMPB on period and use the period action to clear the PWM and a
compare-up action to set the PWM. Modulate the compare value from 0 to
TBPRD to achieve 50%-0% PWM duty.
When using up-count mode to generate an asymmetric PWM:
• To achieve 0-100% asymmetric PWM use the following configuration: Load
CMPA/CMPB on TBPRD. Use the Zero action to set the PWM and a
compare-up action to clear the PWM. Modulate the compare value from 0 to
TBPRD+1 to achieve 0-100% PWM duty.
See the Using Enhanced Pulse Width Modulator (ePWM) Module for 0-100%
Duty Cycle Control Application Report (literature number SPRAAI1)
Figure 23 shows how a symmetric PWM waveform can be generated using the up-down-count mode of
the TBCTR. In this mode 0%-100% DC modulation is achieved by using equal compare matches on the
up count and down count portions of the waveform. In the example shown, CMPA is used to make the
comparison. When the counter is incrementing the CMPA match will pull the PWM output high. Likewise,
when the counter is decrementing the compare match will pull the PWM signal low. When CMPA = 0, the
PWM signal is low for the entire period giving the 0% duty waveform. When CMPA = TBPRD, the PWM
signal is high achieving 100% duty.
When using this configuration in practice, if you load CMPA/CMPB on zero, then use CMPA/CMPB values
greater than or equal to 1. If you load CMPA/CMPB on period, then use CMPA/CMPB values less than or
equal to TBPRD-1. This means there will always be a pulse of at least one TBCLK cycle in a PWM period
which, when very short, tend to be ignored by the system.
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Figure 23. Up-Down-Count Mode Symmetrical Waveform
4
4
Mode: Up-Down Count
TBPRD = 4
CAU = SET, CAD = CLEAR
0% - 100% Duty
3
2
3
3
2
1
1
1
1
TBCTR
2
2
3
0
0
0
TBCTR Direction
UP
DOWN
UP
DOWN
Case 1:
CMPA = 4, 0% Duty
EPWMxA/EPWMxB
Case 2:
CMPA = 3, 25% Duty
EPWMxA/EPWMxB
Case 3:
CMPA = 2, 50% Duty
EPWMxA/EPWMxB
Case 3:
CMPA = 1, 75% Duty
EPWMxA/EPWMxB
Case 4:
CMPA = 0, 100% Duty
EPWMxA/EPWMxB
The PWM waveforms in Figure 24 through Figure 29 show some common action-qualifier configurations.
The C-code samples in Example 2 through Example 7 shows how to configure an ePWM module for each
case. Some conventions used in the figures and examples are as follows:
• TBPRD, CMPA, and CMPB refer to the value written in their respective registers. The active register,
not the shadow register, is used by the hardware.
• CMPx, refers to either CMPA or CMPB.
• EPWMxA and EPWMxB refer to the output signals from ePWMx
• Up-Down means Count-up-and-down mode, Up means up-count mode and Dwn means down-count
mode
• Sym = Symmetric, Asym = Asymmetric
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Figure 24. Up, Single Edge Asymmetric Waveform, With Independent Modulation on EPWMxA and
EPWMxB—Active High
TBCTR
TBPRD
value
Z
P
CB
CA
Z
P
CB
CA
Z
P
Z
P
CB
CA
Z
P
CB
CA
Z
P
EPWMxA
EPWMxB
A
PWM period = (TBPRD + 1 ) × TTBCLK
B
Duty modulation for EPWMxA is set by CMPA, and is active high (that is, high time duty proportional to CMPA).
C
Duty modulation for EPWMxB is set by CMPB and is active high (that is, high time duty proportional to CMPB).
D
The "Do Nothing" actions ( X ) are shown for completeness, but will not be shown on subsequent diagrams.
E
Actions at zero and period, although appearing to occur concurrently, are actually separated by one TBCLK period.
TBCTR wraps from period to 0000.
Example 2 contains a code sample showing initialization and run time for the waveforms in Figure 24.
Example 2. Code Sample for Figure 24
// Initialization Time
// = = = = = = = = = = = = = = = = = = = = = = =
EPwm1Regs.TBPRD = 600;
//
EPwm1Regs.CMPA.half.CMPA = 350;
//
EPwm1Regs.CMPB = 200;
//
EPwm1Regs.TBPHS = 0;
//
EPwm1Regs.TBCTR = 0;
//
EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UP;
EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE;
//
EPwm1Regs.TBCTL.bit.PRDLD = TB_SHADOW;
EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_DISABLE;
EPwm1Regs.TBCTL.bit.HSPCLKDIV = TB_DIV1;
//
EPwm1Regs.TBCTL.bit.CLKDIV = TB_DIV1;
EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;
EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;
EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; //
EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; //
EPwm1Regs.AQCTLA.bit.ZRO = AQ_SET;
EPwm1Regs.AQCTLA.bit.CAU = AQ_CLEAR;
EPwm1Regs.AQCTLB.bit.ZRO = AQ_SET;
EPwm1Regs.AQCTLB.bit.CBU = AQ_CLEAR;
//
// Run Time
// = = = = = = = = = = = = = = = = = = = = = = =
EPwm1Regs.CMPA.half.CMPA = Duty1A;
//
EPwm1Regs.CMPB = Duty1B;
//
44
=
Period = 601 TBCLK counts
Compare A = 350 TBCLK counts
Compare B = 200 TBCLK counts
Set Phase register to zero
clear TB counter
Phase loading disabled
TBCLK = SYSCLK
load on CTR = Zero
load on CTR = Zero
=
adjust duty for output EPWM1A
adjust duty for output EPWM1B
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Figure 25. Up, Single Edge Asymmetric Waveform With Independent Modulation on EPWMxA and
EPWMxB—Active Low
TBCTR
TBPRD
value
P
CA
P
CA
P
EPWMxA
P
CB
P
CB
P
EPWMxB
A
PWM period = (TBPRD + 1 ) × TTBCLK
B
Duty modulation for EPWMxA is set by CMPA, and is active low (that is, the low time duty is proportional to CMPA).
C
Duty modulation for EPWMxB is set by CMPB and is active low (that is, the low time duty is proportional to CMPB).
D
Actions at zero and period, although appearing to occur concurrently, are actually separated by one TBCLK period.
TBCTR wraps from period to 0000.
Example 3 contains a code sample showing initialization and run time for the waveforms in Figure 25.
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Example 3. Code Sample for Figure 25
// Initialization Time
// = = = = = = = = = = = = = = = = = = = = = = =
EPwm1Regs.TBPRD = 600;
//
EPwm1Regs.CMPA.half.CMPA = 350;
//
EPwm1Regs.CMPB = 200;
//
EPwm1Regs.TBPHS = 0;
//
EPwm1Regs.TBCTR = 0;
//
EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UP;
EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE;
//
EPwm1Regs.TBCTL.bit.PRDLD = TB_SHADOW;
EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_DISABLE;
EPwm1Regs.TBCTL.bit.HSPCLKDIV = TB_DIV1;
//
EPwm1Regs.TBCTL.bit.CLKDIV = TB_DIV1;
EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;
EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;
EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; //
EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; //
EPwm1Regs.AQCTLA.bit.PRD = AQ_CLEAR;
EPwm1Regs.AQCTLA.bit.CAU = AQ_SET;
EPwm1Regs.AQCTLB.bit.PRD = AQ_CLEAR;
EPwm1Regs.AQCTLB.bit.CBU = AQ_SET;
//
// Run Time
// = = = = = = = = = = = = = = = = = = = = = = =
EPwm1Regs.CMPA.half.CMPA = Duty1A;
//
EPwm1Regs.CMPB = Duty1B;
//
=
Period = 601 TBCLK counts
Compare A = 350 TBCLK counts
Compare B = 200 TBCLK counts
Set Phase register to zero
clear TB counter
Phase loading disabled
TBCLK = SYSCLKOUT
load on TBCTR = Zero
load on TBCTR = Zero
=
adjust duty for output EPWM1A
adjust duty for output EPWM1B
Figure 26. Up-Count, Pulse Placement Asymmetric Waveform With Independent Modulation on EPWMxA
TBCTR
TBPRD
value
CB
CA
CA
CB
EPWMxA
Z
T
Z
T
Z
T
EPWMxB
A
PWM frequency = 1/( (TBPRD + 1 ) × TTBCLK )
B
Pulse can be placed anywhere within the PWM cycle (0000 - TBPRD)
C
High time duty proportional to (CMPB - CMPA)
D
EPWMxB can be used to generate a 50% duty square wave with frequency =
× ( (TBPRD + 1 ) × TBCLK )
Example 4 contains a code sample showing initialization and run time for the waveforms Figure 26. Use
the code in to define the headers.
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Example 4. Code Sample for Figure 26
// Initialization Time
// = = = = = = = = = = = = = = = = = = = = = = = =
EPwm1Regs.TBPRD = 600;
// Period = 601 TBCLK counts
EPwm1Regs.CMPA.half.CMPA = 200;
// Compare A = 200 TBCLK counts
EPwm1Regs.CMPB = 400;
// Compare B = 400 TBCLK counts
EPwm1Regs.TBPHS = 0;
// Set Phase register to zero
EPwm1Regs.TBCTR = 0;
// clear TB counter
EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UP;
EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE;
// Phase loading disabled
EPwm1Regs.TBCTL.bit.PRDLD = TB_SHADOW;
EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_DISABLE;
EPwm1Regs.TBCTL.bit.HSPCLKDIV = TB_DIV1;
// TBCLK = SYSCLKOUT
EPwm1Regs.TBCTL.bit.CLKDIV = TB_DIV1;
EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;
EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;
EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on TBCTR = Zero
EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on TBCTR = Zero
EPwm1Regs.AQCTLA.bit.CAU = AQ_SET;
EPwm1Regs.AQCTLA.bit.CBU = AQ_CLEAR;
EPwm1Regs.AQCTLB.bit.ZRO = AQ_TOGGLE;
//
// Run Time
// = = = = = = = = = = = = = = = = = = = = = = = =
EPwm1Regs.CMPA.half.CMPA = EdgePosA;
// adjust duty for output EPWM1A only
EPwm1Regs.CMPB = EdgePosB;
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Figure 27. Up-Down-Count, Dual Edge Symmetric Waveform, With Independent Modulation on EPWMxA
and EPWMxB — Active Low
TBCTR
TBPRD
value
CA
CA
CA
CA
EPWMxA
CB
CB
CB
CB
EPWMxB
A
PWM period = 2 x TBPRD × TTBCLK
B
Duty modulation for EPWMxA is set by CMPA, and is active low (that is, the low time duty is proportional to CMPA).
C
Duty modulation for EPWMxB is set by CMPB and is active low (that is, the low time duty is proportional to CMPB).
D
Outputs EPWMxA and EPWMxB can drive independent power switches
Example 5 contains a code sample showing initialization and run time for the waveforms in Figure 27. Use
the code in to define the headers.
Example 5. Code Sample for Figure 27
// Initialization Time
// = = = = = = = = = = = = = = = = = = = = = = = =
EPwm1Regs.TBPRD = 600;
// Period = 2´600 TBCLK counts
EPwm1Regs.CMPA.half.CMPA = 400;
// Compare A = 400 TBCLK counts
EPwm1Regs.CMPB = 500;
// Compare B = 500 TBCLK counts
EPwm1Regs.TBPHS = 0;
// Set Phase register to zero
EPwm1Regs.TBCTR = 0;
// clear TB counter
EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; // Symmetric
xEPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE;
// Phase loading disabled
xEPwm1Regs.TBCTL.bit.PRDLD = TB_SHADOW;
EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_DISABLE;
EPwm1Regs.TBCTL.bit.HSPCLKDIV = TB_DIV1;
// TBCLK = SYSCLKOUT
EPwm1Regs.TBCTL.bit.CLKDIV = TB_DIV1;
EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;
EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;
EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on CTR = Zero
EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on CTR = Zero
EPwm1Regs.AQCTLA.bit.CAU = AQ_SET;
EPwm1Regs.AQCTLA.bit.CAD = AQ_CLEAR;
EPwm1Regs.AQCTLB.bit.CBU = AQ_SET;
EPwm1Regs.AQCTLB.bit.CBD = AQ_CLEAR;
//
// Run Time
// = = = = = = = = = = = = = = = = = = = = = = = =
EPwm1Regs.CMPA.half.CMPA = Duty1A;
// adjust duty for output EPWM1A
EPwm1Regs.CMPB = Duty1B;
// adjust duty for output EPWM1B
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Figure 28. Up-Down-Count, Dual Edge Symmetric Waveform, With Independent Modulation on EPWMxA
and EPWMxB — Complementary
TBCTR
TBPRD
value
CA
CA
CA
CA
EPWMxA
CB
CB
CB
CB
EPWMxB
A
PWM period = 2 × TBPRD × TTBCLK
B
Duty modulation for EPWMxA is set by CMPA, and is active low, i.e., low time duty proportional to CMPA
C
Duty modulation for EPWMxB is set by CMPB and is active high, i.e., high time duty proportional to CMPB
D
Outputs EPWMx can drive upper/lower (complementary) power switches
E
Dead-band = CMPB - CMPA (fully programmable edge placement by software). Note the dead-band module is also
available if the more classical edge delay method is required.
Example 6 contains a code sample showing initialization and run time for the waveforms in Figure 28. Use
the code in to define the headers.
Example 6. Code Sample for Figure 28
// Initialization Time
// = = = = = = = = = = = = = = = = = = = = = = = =
EPwm1Regs.TBPRD = 600;
// Period = 2´600 TBCLK counts
EPwm1Regs.CMPA.half.CMPA = 350;
// Compare A = 350 TBCLK counts
EPwm1Regs.CMPB = 400;
// Compare B = 400 TBCLK counts
EPwm1Regs.TBPHS = 0;
// Set Phase register to zero
EPwm1Regs.TBCTR = 0;
// clear TB counter
EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; // Symmetric
EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE;
// Phase loading disabled
EPwm1Regs.TBCTL.bit.PRDLD = TB_SHADOW;
EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_DISABLE;
EPwm1Regs.TBCTL.bit.HSPCLKDIV = TB_DIV1;
// TBCLK = SYSCLKOUT
EPwm1Regs.TBCTL.bit.CLKDIV = TB_DIV1;
EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;
EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;
EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on CTR = Zero
EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on CTR = Zero
EPwm1Regs.AQCTLA.bit.CAU = AQ_SET;
EPwm1Regs.AQCTLA.bit.CAD = AQ_CLEAR;
EPwm1Regs.AQCTLB.bit.CBU = AQ_CLEAR;
EPwm1Regs.AQCTLB.bit.CBD = AQ_SET;
// Run Time
// = = = = = = = = = = = = = = = = = = = = = = = =
EPwm1Regs.CMPA.half.CMPA = Duty1A;
// adjust duty for output EPWM1A
EPwm1Regs.CMPB = Duty1B;
// adjust duty for output EPWM1B
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Figure 29. Up-Down-Count, Dual Edge Asymmetric Waveform, With Independent Modulation on
EPWMxA—Active Low
TBCTR
CA
CA
CB
CB
EPWMxA
Z
P
Z
P
EPWMxB
A
PWM period = 2 × TBPRD × TBCLK
B
Rising edge and falling edge can be asymmetrically positioned within a PWM cycle. This allows for pulse placement
techniques.
C
Duty modulation for EPWMxA is set by CMPA and CMPB.
D
Low time duty for EPWMxA is proportional to (CMPA + CMPB).
E
To change this example to active high, CMPA and CMPB actions need to be inverted (i.e., Set ! Clear and Clear Set).
F
Duty modulation for EPWMxB is fixed at 50% (utilizes spare action resources for EPWMxB)
Example 7 contains a code sample showing initialization and run time for the waveforms in Figure 29. Use
the code in to define the headers.
Example 7. Code Sample for Figure 29
// Initialization Time
// = = = = = = = = = = = = = = = = = = = = = = = =
EPwm1Regs.TBPRD = 600;
//
EPwm1Regs.CMPA.half.CMPA = 250;
//
EPwm1Regs.CMPB = 450;
//
EPwm1Regs.TBPHS = 0;
//
EPwm1Regs.TBCTR = 0;
//
EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; //
EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE;
//
EPwm1Regs.TBCTL.bit.PRDLD = TB_SHADOW;
EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_DISABLE;
EPwm1Regs.TBCTL.bit.HSPCLKDIV = TB_DIV1;
//
EPwm1Regs.TBCTL.bit.CLKDIV = TB_DIV1;
EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;
EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;
EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; //
EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; //
EPwm1Regs.AQCTLA.bit.CAU = AQ_SET;
EPwm1Regs.AQCTLA.bit.CBD = AQ_CLEAR;
EPwm1Regs.AQCTLB.bit.ZRO = AQ_CLEAR;
EPwm1Regs.AQCTLB.bit.PRD = AQ_SET;
// Run Time
// = = = = = = = = = = = = = = = = = = = = = = = =
EPwm1Regs.CMPA.half.CMPA = EdgePosA;
//
EPwm1Regs.CMPB = EdgePosB;
50
Period = 2 ´ 600 TBCLK counts
Compare A = 250 TBCLK counts
Compare B = 450 TBCLK counts
Set Phase register to zero
clear TB counter
Symmetric
Phase loading disabled
TBCLK = SYSCLKOUT
load on CTR = Zero
load on CTR = Zero
adjust duty for output EPWM1A only
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2.5
Dead-Band Generator (DB) Submodule
Figure 30 illustrates the dead-band submodule within the ePWM module.
Figure 30. Dead_Band Submodule
CTR = PRD
CTR = 0
EPWMxSYNCI
EPWMxSYNCO
CTR = PRD
Time-Base
(TB)
Action
Qualifier
(AQ)
CTR = CMPA
CTR = CMPB
CTR_Dir
CTR = 0
EPWMxINT
Event
Trigger
EPWMxSOCA
and
Interrupt
(ET)
ADC
EPWMxSOCB
CTR_Dir
EPWMxA
EPWMxA
Dead
Band
(DB)
CTR = CMPA
Counter
Compare
(CC)
PIE
PWMchopper
(PC)
Trip
Zone
(TZ)
GPIO
EPWMxB
CTR = CMPB
EPWMxB
MUX
CTR = 0
EPWMxTZINT
TZ1 to TZ6
PIE
2.5.1
Purpose of the Dead-Band Submodule
The "Action-qualifier (AQ) Module" section discussed how it is possible to generate the required
dead-band by having full control over edge placement using both the CMPA and CMPB resources of the
ePWM module. However, if the more classical edge delay-based dead-band with polarity control is
required, then the dead-band submodule described here should be used.
The key functions of the dead-band module are:
• Generating appropriate signal pairs (EPWMxA and EPWMxB) with dead-band relationship from a
single EPWMxA input
• Programming signal pairs for:
– Active high (AH)
– Active low (AL)
– Active high complementary (AHC)
– Active low complementary (ALC)
• Adding programmable delay to rising edges (RED)
• Adding programmable delay to falling edges (FED)
• Can be totally bypassed from the signal path (note dotted lines in diagram)
2.5.2
Controlling and Monitoring the Dead-Band Submodule
The dead-band submodule operation is controlled and monitored via the following registers:
Table 13. Dead-Band Generator Submodule Registers
Register Name
Address offset
Shadowed
DBCTL
0x000F
No
Dead-Band Control Register
DBRED
0x0010
No
Dead-Band Rising Edge Delay Count Register
DBFED
0x0011
No
Dead-Band Falling Edge Delay Count Register
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Operational Highlights for the Dead-Band Submodule
The following sections provide the operational highlights.
The dead-band submodule has two groups of independent selection options as shown in Figure 31.
• Input Source Selection:
The input signals to the dead-band module are the EPWMxA and EPWMxB output signals from the
action-qualifier. In this section they will be referred to as EPWMxA In and EPWMxB In. Using the
DBCTL[IN_MODE) control bits, the signal source for each delay, falling-edge or rising-edge, can be
selected:
– EPWMxA In is the source for both falling-edge and rising-edge delay. This is the default mode.
– EPWMxA In is the source for falling-edge delay, EPWMxB In is the source for rising-edge delay.
– EPWMxA In is the source for rising edge delay, EPWMxB In is the source for falling-edge delay.
– EPWMxB In is the source for both falling-edge and rising-edge delay.
• Output Mode Control:
The output mode is configured by way of the DBCTL[OUT_MODE] bits. These bits determine if the
falling-edge delay, rising-edge delay, neither, or both are applied to the input signals.
• Polarity Control:
The polarity control (DBCTL[POLSEL]) allows you to specify whether the rising-edge delayed signal
and/or the falling-edge delayed signal is to be inverted before being sent out of the dead-band
submodule.
Figure 31. Configuration Options for the Dead-Band Submodule
EPWMxA in
0 S4
Rising edge
delay
In
EPWMxA
RED
Out
1
(10-bit
counter)
Falling edge
delay
In
1
0 S1
1
1
0 S5
0 S2
0 S3
FED
1 S0
EPWMxB
Out
1
0
(10-bit
counter)
DBCTL[IN_MODE]
DBCTL[POLSEL]
DBCTL[OUT_MODE]
EPWMxB in
Although all combinations are supported, not all are typical usage modes. Table 14 documents some
classical dead-band configurations. These modes assume that the DBCTL[IN_MODE] is configured such
that EPWMxA In is the source for both falling-edge and rising-edge delay. Enhanced, or non-traditional
modes can be achieved by changing the input signal source. The modes shown in Table 14 fall into the
following categories:
• Mode 1: Bypass both falling-edge delay (FED) and rising-edge delay (RED)
Allows you to fully disable the dead-band submodule from the PWM signal path.
• Mode 2-5: Classical Dead-Band Polarity Settings:
These represent typical polarity configurations that should address all the active high/low modes
required by available industry power switch gate drivers. The waveforms for these typical cases are
shown in Figure 32. Note that to generate equivalent waveforms to Figure 32, configure the
action-qualifier submodule to generate the signal as shown for EPWMxA.
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•
Mode 6: Bypass rising-edge-delay and Mode 7: Bypass falling-edge-delay
Finally the last two entries in Table 14 show combinations where either the falling-edge-delay (FED) or
rising-edge-delay (RED) blocks are bypassed.
Table 14. Classical Dead-Band Operating Modes
Mode
DBCTL[POLSEL]
Mode Description
DBCTL[OUT_MODE]
S3
S2
S1
S0
1
EPWMxA and EPWMxB Passed Through (No Delay)
X
X
0
0
2
Active High Complementary (AHC)
1
0
1
1
3
Active Low Complementary (ALC)
0
1
1
1
4
Active High (AH)
0
0
1
1
5
Active Low (AL)
1
1
1
1
0 or 1
0 or 1
0
1
0 or 1
0 or 1
1
0
6
7
EPWMxA Out = EPWMxA In (No Delay)
EPWMxB Out = EPWMxA In with Falling Edge Delay
EPWMxA Out = EPWMxA In with Rising Edge Delay
EPWMxB Out = EPWMxB In with No Delay
Figure 32 shows waveforms for typical cases where 0% < duty < 100%.
Figure 32. Dead-Band Waveforms for Typical Cases (0% < Duty < 100%)
Period
Original
(outA)
RED
Rising Edge
Delayed (RED)
FED
Falling Edge
Delayed (FED)
Active High
Complementary
(AHC)
Active Low
Complementary
(ALC)
Active High
(AH)
Active Low
(AL)
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The dead-band submodule supports independent values for rising-edge (RED) and falling-edge (FED)
delays. The amount of delay is programmed using the DBRED and DBFED registers. These are 10-bit
registers and their value represents the number of time-base clock, TBCLK, periods a signal edge is
delayed by. For example, the formula to calculate falling-edge-delay and rising-edge-delay are:
FED = DBFED × TTBCLK
RED = DBRED × TTBCLK
Where TTBCLK is the period of TBCLK, the prescaled version of SYSCLKOUT.
For convenience, delay values for various TBCLK options are shown in Table 15.
Table 15. Dead-Band Delay Values in μS as a Function of DBFED and DBRED
Dead-Band Delay in μS
Dead-Band Value
54
DBFED, DBRED
TBCLK = SYSCLKOUT/1
TBCLK = SYSCLKOUT /2
TBCLK = SYSCLKOUT/4
1
0.01 μS
0.02 μS
0.04 μS
5
0.05 μS
0.10 μS
0.20 μS
10
0.10 μS
0.20 μS
0.40 μS
100
1.00 μS
2.00 μS
4.00 μS
200
2.00 μS
4.00 μS
8.00 μS
300
3.00 μS
6.00 μS
12.00 μS
400
4.00 μS
8.00 μS
16.00 μS
500
5.00 μS
10.00 μS
20.00 μS
600
6.00 μS
12.00 μS
24.00 μS
700
7.00 μS
14.00 μS
28.00 μS
800
8.00 μS
16.00 μS
32.00 μS
900
9.00 μS
18.00 μS
36.00 μS
1000
10.00 μS
20.00 μS
40.00 μS
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2.6
PWM-Chopper (PC) Submodule
Figure 33 illustrates the PWM-chopper (PC) submodule within the ePWM module.
Figure 33. PWM-Chopper Submodule
CTR = PRD
CTR = 0
EPWMxSYNCI
EPWMxSYNCO
CTR = PRD
Time-Base
(TB)
Action
Qualifier
(AQ)
CTR = CMPA
CTR = CMPB
CTR_Dir
CTR = 0
EPWMxINT
Event
Trigger
EPWMxSOCA
and
Interrupt
(ET)
ADC
EPWMxSOCB
CTR_Dir
EPWMxA
EPWMxB
Dead
Band
(DB)
CTR = CMPA
Counter
Compare
(CC)
PIE
PWMchopper
(PC)
Trip
Zone
(TZ)
GPIO
EPWMxB
CTR = CMPB
EPWMxA
MUX
CTR = 0
TZ1 to TZ6
EPWMxTZINT
PIE
The PWM-chopper submodule allows a high-frequency carrier signal to modulate the PWM waveform
generated by the action-qualifier and dead-band submodules. This capability is important if you need
pulse transformer-based gate drivers to control the power switching elements.
2.6.1
Purpose of the PWM-Chopper Submodule
The key functions of the PWM-chopper submodule are:
• Programmable chopping (carrier) frequency
• Programmable pulse width of first pulse
• Programmable duty cycle of second and subsequent pulses
• Can be fully bypassed if not required
2.6.2
Controlling the PWM-Chopper Submodule
The PWM-chopper submodule operation is controlled via the registers in Table 16.
Table 16. PWM-Chopper Submodule Registers
2.6.3
mnemonic
Address offset
Shadowed
PCCTL
0x001E
No
Description
PWM-chopper Control Register
Operational Highlights for the PWM-Chopper Submodule
Figure 34 shows the operational details of the PWM-chopper submodule. The carrier clock is derived from
SYSCLKOUT. Its frequency and duty cycle are controlled via the CHPFREQ and CHPDUTY bits in the
PCCTL register. The one-shot block is a feature that provides a high energy first pulse to ensure hard and
fast power switch turn on, while the subsequent pulses sustain pulses, ensuring the power switch remains
on. The one-shot width is programmed via the OSHTWTH bits. The PWM-chopper submodule can be fully
disabled (bypassed) via the CHPEN bit.
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Figure 34. PWM-Chopper Submodule Operational Details
Bypass
0
EPWMxA
EPWMxA
Start
One
shot
OSHT
PWMA_ch
1
Clk
Pulse-width
SYSCLKOUT
/8
PCCTL
[OSHTWTH]
PCCTL
[OSHTWTH]
Pulse-width
Divider and
duty control
PCCTL
[CHPEN]
PSCLK
PCCTL[CHPFREQ]
PCCTL[CHPDUTY]
Clk
One
shot
EPWMxB
PWMB_ch
1
OSHT
EPWMxB
Start
Bypass
2.6.4
0
Waveforms
Figure 35 shows simplified waveforms of the chopping action only; one-shot and duty-cycle control are not
shown. Details of the one-shot and duty-cycle control are discussed in the following sections.
Figure 35. Simple PWM-Chopper Submodule Waveforms Showing Chopping Action Only
EPWMxA
EPWMxB
PSCLK
EPWMxA
EPWMxB
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2.6.4.1
One-Shot Pulse
The width of the first pulse can be programmed to any of 16 possible pulse width values. The width or
period of the first pulse is given by:
T1stpulse = TSYSCLKOUT × 8 × OSHTWTH
Where TSYSCLKOUT is the period of the system clock (SYSCLKOUT) and OSHTWTH is the four control bits
(value from 1 to 16)
Figure 36 shows the first and subsequent sustaining pulses and Table 7.3 gives the possible pulse width
values for a SYSCLKOUT = 100 MHz.
Figure 36. PWM-Chopper Submodule Waveforms Showing the First Pulse and Subsequent Sustaining
Pulses
Start OSHT pulse
EPWMxA in
PSCLK
Prog. pulse width
(OSHTWTH)
OSHT
EPWMxA out
Sustaining pulses
Table 17. Possible Pulse Width Values for SYSCLKOUT
= 100 MHz
OSHTWTHz
(hex)
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Pulse Width
(nS)
0
80
1
160
2
240
3
320
4
400
5
480
6
560
7
640
8
720
9
800
A
880
B
960
C
1040
D
1120
E
1200
F
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Duty Cycle Control
Pulse transformer-based gate drive designs need to comprehend the magnetic properties or
characteristics of the transformer and associated circuitry. Saturation is one such consideration. To assist
the gate drive designer, the duty cycles of the second and subsequent pulses have been made
programmable. These sustaining pulses ensure the correct drive strength and polarity is maintained on the
power switch gate during the on period, and hence a programmable duty cycle allows a design to be
tuned or optimized via software control.
Figure 37 shows the duty cycle control that is possible by programming the CHPDUTY bits. One of seven
possible duty ratios can be selected ranging from 12.5% to 87.5%.
Figure 37. PWM-Chopper Submodule Waveforms Showing the Pulse Width (Duty Cycle) Control of
Sustaining Pulses
PSCLK
PSCLK
period
75%
50%
25%
62.5% 37.5%
87.5%
12.5%
PSCLK Period
Duty
1/8
Duty
2/8
Duty
3/8
Duty
4/8
Duty
5/8
Duty
6/8
Duty
7/8
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2.7
Trip-Zone (TZ) Submodule
Figure 38 shows how the trip-zone (TZ) submodule fits within the ePWM module.
Figure 38. Trip-Zone Submodule
CTR = PRD
CTR = 0
EPWMxSYNCI
EPWMxSYNCO
CTR = PRD
Time-Base
(TB)
Action
Qualifier
(AQ)
CTR = CMPA
CTR = CMPB
CTR_Dir
CTR = 0
EPWMxINT
Event
Trigger
EPWMxSOCA
and
Interrupt
(ET)
ADC
EPWMxSOCB
CTR_Dir
EPWMxA
EPWMxA
Dead
Band
(DB)
CTR = CMPA
Counter
Compare
(CC)
PIE
PWMchopper
(PC)
Trip
Zone
(TZ)
GPIO
EPWMxB
CTR = CMPB
EPWMxB
MUX
CTR = 0
EPWMxTZINT
TZ1 to TZ6
PIE
Each ePWM module is connected to six TZn signals (TZ1 to TZ6) that are sourced from the GPIO MUX.
These signals indicate external fault or trip conditions, and the ePWM outputs can be programmed to
respond accordingly when faults occur.
2.7.1
Purpose of the Trip-Zone Submodule
The key functions of the Trip-Zone submodule are:
• Trip inputs TZ1 to TZ6 can be flexibly mapped to any ePWM module.
• Upon a fault condition, outputs EPWMxA and EPWMxB can be forced to one of the following:
– High
– Low
– High-impedance
– No action taken
• Support for one-shot trip (OSHT) for major short circuits or over-current conditions.
• Support for cycle-by-cycle tripping (CBC) for current limiting operation.
• Each trip-zone input pin can be allocated to either one-shot or cycle-by-cycle operation.
• Interrupt generation is possible on any trip-zone pin .
• Software-forced tripping is also supported.
• The trip-zone submodule can be fully bypassed if it is not required.
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Controlling and Monitoring the Trip-Zone Submodule
The trip-zone submodule operation is controlled and monitored through the following registers:
Table 18. Trip-Zone Submodule Registers
(1)
2.7.3
Description
(1)
Register Name
Address offset
Shadowed
No
Trip-Zone Select Register
TZSEL
0x0012
reserved
0x0013
TZCTL
0x0014
No
Trip-Zone Control Register
TZEINT
0x0015
No
Trip-Zone Enable Interrupt Register
TZFLG
0x0016
No
Trip-Zone Flag Register
TZCLR
0x0017
No
Trip-Zone Clear Register
TZFRC
0x0018
No
Trip-Zone Force Register
All trip-zone registers are EALLOW protected and can be modified only after executing the EALLOW instruction. For more
information, see the device-specific version of the System Control and Interrupts Reference Guide listed in Section 1.
Operational Highlights for the Trip-Zone Submodule
The following sections describe the operational highlights and configuration options for the trip-zone
submodule.
The trip-zone signals at pins TZ1 to TZ6 (also collectively referred to as TZn) are active low input signals.
When one of these pins goes low, it indicates that a trip event has occurred. Each ePWM module can be
individually configured to ignore or use each of the trip-zone pins . Which trip-zone pins are used by a
particular ePWM module is determined by the TZSEL register for that specific ePWM module. The
trip-zone signals may or may not be synchronized to the system clock (SYSCLKOUT) and digitally filtered
within the GPIO MUX block. A minimum 1 SYSCLKOUT low pulse on TZn inputs is sufficient to trigger a
fault condition in the ePWM module. The asynchronous trip makes sure that if clocks are missing for any
reason, the outputs can still be tripped by a valid event present on TZn inputs , providing the GPIO is
appropriately configured . For more information, see the GPIO section of the device-specific version of the
System Control and Interrupts Reference Guide listed in Related Documentation From Texas Instruments.
Each TZn input can be individually configured to provide either a cycle-by-cycle or one-shot trip event for
an ePWM module. This configuration is determined by the TZSEL[CBCn], and TZSEL[OSHTn] control bits
(where n corresponds to the trip pin) respectively.
•
•
Cycle-by-Cycle (CBC):
When a cycle-by-cycle trip event occurs, the action specified in the TZCTL register is carried out
immediately on the EPWMxA and/or EPWMxB output. Table 19 lists the possible actions. In addition,
the cycle-by-cycle trip event flag (TZFLG[CBC]) is set and a EPWMx_TZINT interrupt is generated if it
is enabled in the TZEINT register and PIE peripheral.
The specified condition on the pins is automatically cleared when the ePWM time-base counter
reaches zero (TBCTR = 0x0000) if the trip event is no longer present. Therefore, in this mode, the trip
event is cleared or reset every PWM cycle. The TZFLG[CBC] flag bit will remain set until it is manually
cleared by writing to the TZCLR[CBC] bit. If the cycle-by-cycle trip event is still present when the
TZFLG[CBC] bit is cleared, then it will again be immediately set.
One-Shot (OSHT):
When a one-shot trip event occurs, the action specified in the TZCTL register is carried out
immediately on the EPWMxA and/or EPWMxB output. Table 19 lists the possible actions. In addition,
the one-shot trip event flag (TZFLG[OST]) is set and a EPWMx_TZINT interrupt is generated if it is
enabled in the TZEINT register and PIE peripheral. The one-shot trip condition must be cleared
manually by writing to the TZCLR[OST] bit.
The action taken when a trip event occurs can be configured individually for each of the ePWM output
pins by way of the TZCTL[TZA] and TZCTL[TZB] register bits fields. One of four possible actions, shown
in Table 19, can be taken on a trip event.
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Table 19. Possible Actions On a Trip Event
TZCTL[TZA]
and/or
TZCTL[TZB]
EPWMxA
and/or
EPWMxB
Comment
0,0
High-Impedance
Tripped
0,1
Force to High State
Tripped
1,0
Force to Low State
Tripped
1,1
No Change
Do Nothing.
No change is made to the output.
Example 8. Trip-Zone Configurations
Scenario A:
A one-shot trip event on TZ1 pulls both EPWM1A, EPWM1B low and also forces EPWM2A and EPWM2B
high.
• Configure the ePWM1 registers as follows:
– TZSEL[OSHT1] = 1: enables TZ1 as a one-shot event source for ePWM1
– TZCTL[TZA] = 2: EPWM1A will be forced low on a trip event.
– TZCTL[TZB] = 2: EPWM1B will be forced low on a trip event.
• Configure the ePWM2 registers as follows:
– TZSEL[OSHT1] = 1: enables TZ1 as a one-shot event source for ePWM2
– TZCTL[TZA] = 1: EPWM2A will be forced high on a trip event.
– TZCTL[TZB] = 1: EPWM2B will be forced high on a trip event.
Scenario B:
A cycle-by-cycle event on TZ5 pulls both EPWM1A, EPWM1B low.
A one-shot event on TZ1 or TZ6 puts EPWM2A into a high impedance state.
• Configure the ePWM1 registers as follows:
– TZSEL[CBC5] = 1: enables TZ5 as a one-shot event source for ePWM1
– TZCTL[TZA] = 2: EPWM1A will be forced low on a trip event.
– TZCTL[TZB] = 2: EPWM1B will be forced low on a trip event.
• Configure the ePWM2 registers as follows:
– TZSEL[OSHT1] = 1: enables TZ1 as a one-shot event source for ePWM2
– TZSEL[OSHT6] = 1: enables TZ6 as a one-shot event source for ePWM2
– TZCTL[TZA] = 0: EPWM2A will be put into a high-impedance state on a trip event.
– TZCTL[TZB] = 3: EPWM2B will ignore the trip event.
2.7.4
Generating Trip Event Interrupts
Figure 39 and Figure 40 illustrate the trip-zone submodule control and interrupt logic, respectively.
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Figure 39. Trip-Zone Submodule Mode Control Logic
TZCTL[TZB]
TZCTL[TZA]
EPWMxA
EPWMxB
Trip
logic
Clear
Latch
cyc−by-cyc
mode
(CBC)
CTR=zero
TZFRC[CBC]
Trip
EPWMxA
EPWMxB
CBC
trip event
Set
TZ1
TZ2
TZ3
TZ4
TZ5
TZ6
Set
Sync
TZFLG[CBC]
TZCLR[CBC]
Clear
TZSEL[CBC1 to CBC6]
Clear
Latch
one-shot
mode
(OSHT)
Set
TZCLR[OST]
TZFRC[OSHT]
TZ1
TZ2
TZ3
TZ4
TZ5
TZ6
Trip
OSHT
trip event
Sync
Async Trip
TZSEL[OSHT1 to OSHT6]
Set
TZFLG[OST]
Clear
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Figure 40. Trip-Zone Submodule Interrupt Logic
TZFLG[INT]
TZCLR[INT]
TZFLG[CBC]
Clear
Clear
Latch
TZCLR[CBC]
Latch
Set
CBC
trip event
Set
TZEINT[CBC]
TZFLG[OST]
EPWMx_TZINT
(PIE)
Generate
interrupt
pulse when
input=1
Clear
Latch
OSHT
trip event
Set
TZEINT[OST]
2.8
TZCLR[OST]
Event-Trigger (ET) Submodule
The key functions of the event-trigger submodule are:
• Receives event inputs generated by the time-base and counter-compare submodules
• Uses the time-base direction information for up/down event qualification
• Uses prescaling logic to issue interrupt requests and ADC start of conversion at:
– Every event
– Every second event
– Every third event
• Provides full visibility of event generation via event counters and flags
• Allows software forcing of Interrupts and ADC start of conversion
The event-trigger submodule manages the events generated by the time-base submodule, the
counter-compare submodule, and the digital-compare submodule to generate an interrupt to the CPU
and/or a start of conversion pulse to the ADC when a selected event occurs. Figure 41 illustrates where
the event-trigger submodule fits within the ePWM system.
Figure 41. Event-Trigger Submodule
CTR = PRD
CTR = CMPA
Event
Trigger
and
CTR = CMPB
Interrupt
CTR = 0
EPWMxSYNCI
EPWMxSYNCO
CTR = PRD
Time-Base
(TB)
Action
Qualifier
(AQ)
CTR_Dir
CTR = 0
(ET)
EPWMxSOCB
EPWMxA
Dead
Band
(DB)
CTR = CMPA
CTR = CMPB
PWMchopper
(PC)
Trip
Zone
(TZ)
EPWMxB
EPWMB
CTR = 0
EPWMxTZINT
2.8.1
EPWMxSOCA
CTR_Dir
EPWMA
Counter
Compare
(CC)
EPWMxINT
TZ1 to TZ6
Operational Overview of the Event-Trigger Submodule
The following sections describe the event-trigger submodule's operational highlights.
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Each ePWM module has one interrupt request line connected to the PIE and two start of conversion
signals (one for each sequencer) connected to the ADC module. As shown in Figure 42, ADC start of
conversion for all ePWM modules are ORed together and hence multiple modules can initiate an ADC
start of conversion. If two requests occur on one start of conversion line, then only one will be recognized
by the ADC.
Figure 42. Event-Trigger Submodule Inter-Connectivity of ADC Start of Conversion
EXTSOCAG1
POLSEL
0
EXTSOCAG1
1
ePWM1SOCA
ePWM1
ePWM1SOCB
EXTSOCBG1
POLSEL
ePWM2SOCA
ePWM2
ePWM2SOCB
0
ePWM3SOCA
1
ePWM3
ePWM3SOCB
EXTSOCAG4
POLSEL
ePWM4SOCA
ePWM4
0
ePWM4SOCB
EXTSOCAG4
1
ePWM5SOCA
ePWM5
ePWM5SOCB
EXTSOCBG4
POLSEL
ePWM6SOCA
ePWM6
0
EXTSOCBG4
ePWM6SOCB
1
ePWM7SOCA
ePWM7
ePWM7SOCB
ePWM8SOCA
ePWM8
EXTSOCAG7
POLSEL
ePWM4SOCB
Pulse Stretcher,
32 HSPCLK Cycles Wide and Then to Chip Pins
EXTSOCSBG1
0
EXTSOCAG7
ePWM9SOCA
ePWM9
1
ePWM9SOCB
EXTSOCBG7
POLSEL
0
EXTSOCBG7
1
The event-trigger submodule monitors various event conditions (the left side inputs to event-trigger
submodule shown in Figure 43) and can be configured to prescale these events before issuing an
Interrupt request or an ADC start of conversion. The event-trigger prescaling logic can issue Interrupt
requests and ADC start of conversion at:
• Every event
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•
•
Every second event
Every third event
Figure 43. Event-Trigger Submodule Showing Event Inputs and Prescaled Outputs
clear
CTR=Zero
Event Trigger
Module Logic
CTR=PRD
EPWMxINTn
PIE
count
CTRU=CMPA
CTR=CMPA
clear
ETSEL reg
CTRD=CMPA
Direction
qualifier
CTR=CMPB
/n
CTRU=CMPB
/n
EPWMxSOCA
ETPS reg
count
CTRD=CMPB
ETFLG reg
ADC
clear
EPWMxSOCB
ETCLR reg
/n
CTR_dir
ETFRC reg
count
The key registers used to configure the event-trigger submodule are shown in Table 20:
Table 20. Event-Trigger Submodule Registers
•
•
•
•
•
Register Name
Address offset
Shadowed
ETSEL
0x0019
No
Description
Event-trigger Selection Register
ETPS
0x001A
No
Event-trigger Prescale Register
ETFLG
0x001B
No
Event-trigger Flag Register
ETCLR
0x001C
No
Event-trigger Clear Register
ETFRC
0x001D
No
Event-trigger Force Register
ETSEL—This selects which of the possible events will trigger an interrupt or start an ADC conversion
ETPS—This programs the event prescaling options mentioned above.
ETFLG—These are flag bits indicating status of the selected and prescaled events.
ETCLR—These bits allow you to clear the flag bits in the ETFLG register via software.
ETFRC—These bits allow software forcing of an event. Useful for debugging or s/w intervention.
A more detailed look at how the various register bits interact with the Interrupt and ADC start of
conversion logic are shown in Figure 44, Figure 45, and Figure 46.
Figure 44 shows the event-trigger's interrupt generation logic. The interrupt-period (ETPS[INTPRD]) bits
specify the number of events required to cause an interrupt pulse to be generated. The choices available
are:
• Do not generate an interrupt.
• Generate an interrupt on every event
• Generate an interrupt on every second event
• Generate an interrupt on every third event
Which event can cause an interrupt is configured by the interrupt selection (ETSEL[INTSEL]) bits. The
event can be one of the following:
• Time-base counter equal to zero (TBCTR = 0x0000).
• Time-base counter equal to period (TBCTR = TBPRD).
• Time-base counter equal to the compare A register (CMPA) when the timer is incrementing.
• Time-base counter equal to the compare A register (CMPA) when the timer is decrementing.
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•
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Time-base counter equal to the compare B register (CMPB) when the timer is incrementing.
Time-base counter equal to the compare B register (CMPB) when the timer is decrementing.
The number of events that have occurred can be read from the interrupt event counter (ETPS[INTCNT])
register bits. That is, when the specified event occurs the ETPS[INTCNT] bits are incremented until they
reach the value specified by ETPS[INTPRD]. When ETPS[INTCNT] = ETPS[INTPRD] the counter stops
counting and its output is set. The counter is only cleared when an interrupt is sent to the PIE.
When ETPS[INTCNT] reaches ETPS[INTPRD] the following behaviors will occur:
• If interrupts are enabled, ETSEL[INTEN] = 1 and the interrupt flag is clear, ETFLG[INT] = 0, then an
interrupt pulse is generated and the interrupt flag is set, ETFLG[INT] = 1, and the event counter is
cleared ETPS[INTCNT] = 0. The counter will begin counting events again.
• If interrupts are disabled, ETSEL[INTEN] = 0, or the interrupt flag is set, ETFLG[INT] = 1, the counter
stops counting events when it reaches the period value ETPS[INTCNT] = ETPS[INTPRD].
• If interrupts are enabled, but the interrupt flag is already set, then the counter will hold its output high
until the ENTFLG[INT] flag is cleared. This allows for one interrupt to be pending while one is serviced.
Writing to the INTPRD bits will automatically clear the counter INTCNT = 0 and the counter output will be
reset (so no interrupts are generated). Writing a 1 to the ETFRC[INT] bit will increment the event counter
INTCNT. The counter will behave as described above when INTCNT = INTPRD. When INTPRD = 0, the
counter is disabled and hence no events will be detected and the ETFRC[INT] bit is also ignored.
The above definition means that you can generate an interrupt on every event, on every second event, or
on every third event. An interrupt cannot be generated on every fourth or more events.
Figure 44. Event-Trigger Interrupt Generator
ETCLR[INT]
Clear
Set
Latch
ETFLG[INT]
ETPS[INTCNT]
EPWMxINT
Generate
interrupt
pulse
when
input = 1
1
ETSEL[INTSEL]
0
Clear CNT
2-bit
Counter
0
ETFRC[INT]
Inc CNT
ETSEL[INT]
ETPS[INTPRD]
000
001
010
011
100
101
101
111
0
CTR=Zero
CTR=PRD
0
CTRU=CMPA
CTRD=CMPA
CTRU=CMPB
CTRD=CMPB
Figure 45 shows the operation of the event-trigger's start-of-conversion-A (SOCA) pulse generator. The
ETPS[SOCACNT] counter and ETPS[SOCAPRD] period values behave similarly to the interrupt generator
except that the pulses are continuously generated. That is, the pulse flag ETFLG[SOCA] is latched when a
pulse is generated, but it does not stop further pulse generation. The enable/disable bit ETSEL[SOCAEN]
stops pulse generation, but input events can still be counted until the period value is reached as with the
interrupt generation logic. The event that will trigger an SOCA and SOCB pulse can be configured
separately in the ETSEL[SOCASEL] and ETSEL[SOCBSEL] bits. The possible events are the same
events that can be specified for the interrupt generation logic .
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Figure 45. Event-Trigger SOCA Pulse Generator
ETCLR[SOCA]
Clear
Latch
Set
ETFLG[SOCA]
ETPS[SOCACNT]
ETSEL[SOCASEL]
Generate
SOC
pulse
when
input = 1
SOCA
Clear CNT
2-bit
Counter
ETFRC[SOCA]
000
001
010
011
100
101
101
111
Inc CNT
ETSEL[SOCAEN]
ETPS[SOCAPRD]
0
CTR=Zero
CTR=PRD
0
CTRU=CMPA
CTRD=CMPA
CTRU=CMPB
CTRD=CMPB
Figure 46 shows the operation of the event-trigger's start-of-conversion-B (SOCB) pulse generator. The
event-trigger's SOCB pulse generator operates the same way as the SOCA.
Figure 46. Event-Trigger SOCB Pulse Generator
ETCLR[SOCB]
Clear
Latch
Set
ETFLG[SOCB]
ETPS[SOCBCNT]
ETSEL[SOCBSEL]
SOCB
Generate
SOC
pulse
when
input = 1
Clear CNT
ETFRC[SOCB]
2-bit
Counter
Inc CNT
ETSEL[SOCBEN]
ETPS[SOCBPRD]
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000
001
010
011
100
101
101
111
0
CTR=Zero
CTR=PRD
0
CTRU=CMPA
CTRD=CMPA
CTRU=CMPB
CTRD=CMPB
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Applications to Power Topologies
An ePWM module has all the local resources necessary to operate completely as a standalone module or
to operate in synchronization with other identical ePWM modules.
3.1
Overview of Multiple Modules
Previously in this user's guide, all discussions have described the operation of a single module. To
facilitate the understanding of multiple modules working together in a system, the ePWM module
described in reference is represented by the more simplified block diagram shown in Figure 47. This
simplified ePWM block shows only the key resources needed to explain how a multiswitch power topology
is controlled with multiple ePWM modules working together.
Figure 47. Simplified ePWM Module
SyncIn
Phase reg
EN
Φ=0°
EPWMxA
EPWMxB
CTR = 0
CTR=CMPB
X
SyncOut
3.2
Key Configuration Capabilities
The key configuration choices available to each module are as follows:
• Options for SyncIn
– Load own counter with phase register on an incoming sync strobe—enable (EN) switch closed
– Do nothing or ignore incoming sync strobe—enable switch open
– Sync flow-through - SyncOut connected to SyncIn
– Master mode, provides a sync at PWM boundaries—SyncOut connected to CTR = PRD
– Master mode, provides a sync at any programmable point in time—SyncOut connected to CTR =
CMPB
– Module is in standalone mode and provides No sync to other modules—SyncOut connected to X
(disabled)
• Options for SyncOut
– Sync flow-through - SyncOut connected to SyncIn
– Master mode, provides a sync at PWM boundaries—SyncOut connected to CTR = PRD
– Master mode, provides a sync at any programmable point in time—SyncOut connected to CTR =
CMPB
– Module is in standalone mode and provides No sync to other modules—SyncOut connected to X
(disabled)
For each choice of SyncOut, a module may also choose to load its own counter with a new phase value
on a SyncIn strobe input or choose to ignore it, i.e., via the enable switch. Although various combinations
are possible, the two most common—master module and slave module modes—are shown in Figure 48.
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Figure 48. EPWM1 Configured as a Typical Master, EPWM2 Configured as a Slave
Ext SyncIn
(optional)
Master
Slave
Phase reg
SyncIn
Phase reg EN
Φ=0°
EN
3.3
Φ=0°
EPWM1A
EPWM1B
CTR=0
CTR=CMPB
X
1
SyncIn
SyncOut
EPWM2A
EPWM2B
CTR=0
CTR=CMPB
X
2
SyncOut
Controlling Multiple Buck Converters With Independent Frequencies
One of the simplest power converter topologies is the buck. A single ePWM module configured as a
master can control two buck stages with the same PWM frequency. If independent frequency control is
required for each buck converter, then one ePWM module must be allocated for each converter stage.
Figure 49 shows four buck stages, each running at independent frequencies. In this case, all four ePWM
modules are configured as Masters and no synchronization is used. Figure 50 shows the waveforms
generated by the setup shown in Figure 49; note that only three waveforms are shown, although there are
four stages.
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Figure 49. Control of Four Buck Stages. Here FPWM1≠ FPWM2≠ FPWM3≠ FPWM4
Ext SyncIn
(optional)
Master1
Phase reg
Φ=X
SyncIn
En
Vin1
EPWM1B
CTR=zero
CTR=CMPB
X
1
Buck #1
EPWM1A
SyncOut
Master2
Phase reg
Φ=X
SyncIn
Vin2
Vout2
En
EPWM2A
2
Buck #2
EPWM2B
CTR=zero
CTR=CMPB
X
EPWM2A
SyncOut
Master3
Phase reg
Φ=X
SyncIn
Vin3
En
Vout3
EPWM3A
3
Buck #3
EPWM3B
CTR=zero
CTR=CMPB
X
EPWM3A
SyncOut
Master4
Phase reg
Φ=X
Vin4
SyncIn
Vout4
En
EPWM4A
Buck #4
EPWM4B
CTR=zero
CTR=CMPB
X
3
Vout1
EPWM1A
EPWM4A
SyncOut
NOTE: Θ = X indicates value in phase register is a "don't care"
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Figure 50. Buck Waveforms for Figure 49 (Note: Only three bucks shown here)
P
I
P
I
P
I
P
700
950
CA
CB
A
1200
P
CA
P
EPWM1A
Pulse center
P
700
1150
CA
CB
A
1400
P
CA
EPWM2A
650
500
CA
P
800
CA
P
CA
P
CB
A
EPWM3A
P
I
Indicates this event triggers an interrupt
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CB
A
Indicates this event triggers an ADC start
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Example 9. Configuration for Example in Figure 50
//=====================================================================
// (Note: code for only 3 modules shown)
// Initialization Time
//========================
// EPWM Module 1 config
EPwm1Regs.TBPRD = 1200;
// Period = 1201 TBCLK counts
EPwm1Regs.TBPHS.half.TBPHS = 0;
// Set Phase register to zero
EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UP;
// Asymmetrical mode
EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE;
// Phase loading disabled
EPwm1Regs.TBCTL.bit.PRDLD = TB_SHADOW;
EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_DISABLE;
EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;
EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;
EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO;
// load on CTR=Zero
EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO;
// load on CTR=Zero
EPwm1Regs.AQCTLA.bit.PRD = AQ_CLEAR;
EPwm1Regs.AQCTLA.bit.CAU = AQ_SET;
// EPWM Module 2 config
EPwm2Regs.TBPRD = 1400;
// Period = 1401 TBCLK counts
EPwm2Regs.TBPHS.half.TBPHS = 0;
// Set Phase register to zero
EPwm2Regs.TBCTL.bit.CTRMODE = TB_COUNT_UP;
// Asymmetrical mode
EPwm2Regs.TBCTL.bit.PHSEN = TB_DISABLE;
// Phase loading disabled
EPwm2Regs.TBCTL.bit.PRDLD = TB_SHADOW;
EPwm2Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_DISABLE;
EPwm2Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;
EPwm2Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;
EPwm2Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO;
// load on CTR=Zero
EPwm2Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO;
// load on CTR=Zero
EPwm2Regs.AQCTLA.bit.PRD = AQ_CLEAR;
EPwm2Regs.AQCTLA.bit.CAU = AQ_SET;
// EPWM Module 3 config
EPwm3Regs.TBPRD = 800;
// Period = 801 TBCLK counts
EPwm3Regs.TBPHS.half.TBPHS = 0;
// Set Phase register to zero
EPwm3Regs.TBCTL.bit.CTRMODE = TB_COUNT_UP;
EPwm3Regs.TBCTL.bit.PHSEN = TB_DISABLE;
// Phase loading disabled
EPwm3Regs.TBCTL.bit.PRDLD = TB_SHADOW;
EPwm3Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_DISABLE;
EPwm3Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;
EPwm3Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;
EPwm3Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO;
// load on CTR=Zero
EPwm3Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO;
// load on CTR=Zero
EPwm3Regs.AQCTLA.bit.PRD = AQ_CLEAR;
EPwm3Regs.AQCTLA.bit.CAU = AQ_SET;
//
// Run Time (Note: Example execution of one run-time instant)
//=========================================================
EPwm1Regs.CMPA.half.CMPA = 700;
// adjust duty for output EPWM1A
EPwm2Regs.CMPA.half.CMPA = 700;
// adjust duty for output EPWM2A
EPwm3Regs.CMPA.half.CMPA = 500;
// adjust duty for output EPWM3A
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3.4
Controlling Multiple Buck Converters With Same Frequencies
If synchronization is a requirement, ePWM module 2 can be configured as a slave and can operate at
integer multiple (N) frequencies of module 1. The sync signal from master to slave ensures these modules
remain locked. Figure 51 shows such a configuration; Figure 52 shows the waveforms generated by the
configuration.
Figure 51. Control of Four Buck Stages. (Note: FPWM2 = N x FPWM1)
Vin1
Buck #1
Ext SyncIn
(optional)
Master
Phase reg
Φ=0°
Vout1
EPWM1A
SyncIn
En
EPWM1A
Vin2
EPWM1B
CTR=zero
CTR=CMPB
Vout2
Buck #2
EPWM1B
X
SyncOut
Vin3
Buck #3
Slave
Phase reg
Φ=X
Vout3
EPWM2A
SyncIn
En
EPWM2A
EPWM2B
CTR=zero
CTR=CMPB
X
Vin4
Vout4
Buck #4
SyncOut
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Figure 52. Buck Waveforms for Figure 51 (Note: FPWM2 = FPWM1))
600
Z
I
400
Z
I
Z
I
400
200
200
CA
P
A
CA
CA
P
A
CA
EPWM1A
CB
CB
CB
CB
EPWM1B
500
500
300
300
CA
CA
CA
CA
EPWM2A
CB
CB
CB
CB
EPWM2B
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Example 10. Code Snippet for Configuration in Figure 51
//========================
// EPWM Module 1 config
EPwm1Regs.TBPRD = 600;
// Period = 1200 TBCLK counts
EPwm1Regs.TBPHS.half.TBPHS = 0;
// Set Phase register to zero
EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; // Symmetrical mode
EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE;
// Master module
EPwm1Regs.TBCTL.bit.PRDLD = TB_SHADOW;
EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_CTR_ZERO;
// Sync down-stream module
EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;
EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;
EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on CTR=Zero
EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on CTR=Zero
EPwm1Regs.AQCTLA.bit.CAU = AQ_SET;
// set actions for EPWM1A
EPwm1Regs.AQCTLA.bit.CAD = AQ_CLEAR;
EPwm1Regs.AQCTLB.bit.CBU = AQ_SET;
// set actions for EPWM1B
EPwm1Regs.AQCTLB.bit.CBD = AQ_CLEAR;
// EPWM Module 2 config
EPwm2Regs.TBPRD = 600;
// Period = 1200 TBCLK counts
EPwm2Regs.TBPHS.half.TBPHS = 0;
// Set Phase register to zero
EPwm2Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; // Symmetrical mode
EPwm2Regs.TBCTL.bit.PHSEN = TB_ENABLE;
// Slave module
EPwm2Regs.TBCTL.bit.PRDLD = TB_SHADOW;
EPwm2Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_IN;
// sync flow-through
EPwm2Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;
EPwm2Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;
EPwm2Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on CTR=Zero
EPwm2Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on CTR=Zero
EPwm2Regs.AQCTLA.bit.CAU = AQ_SET;
// set actions for EPWM2A
EPwm2Regs.AQCTLA.bit.CAD = AQ_CLEAR;
EPwm2Regs.AQCTLB.bit.CBU = AQ_SET;
// set actions for EPWM2B
EPwm2Regs.AQCTLB.bit.CBD = AQ_CLEAR;
//
// Run Time (Note: Example execution of one run-time instance)
//===========================================================
EPwm1Regs.CMPA.half.CMPA = 400;
// adjust duty for output EPWM1A
EPwm1Regs.CMPB = 200;
// adjust duty for output EPWM1B
EPwm2Regs.CMPA.half.CMPA = 500;
// adjust duty for output EPWM2A
EPwm2Regs.CMPB = 300;
// adjust duty for output EPWM2B
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Controlling Multiple Half H-Bridge (HHB) Converters
Topologies that require control of multiple switching elements can also be addressed with these same
ePWM modules. It is possible to control a Half-H bridge stage with a single ePWM module. This control
can be extended to multiple stages. Figure 53 shows control of two synchronized Half-H bridge stages
where stage 2 can operate at integer multiple (N) frequencies of stage 1. Figure 54 shows the waveforms
generated by the configuration shown in Figure 53.
Module 2 (slave) is configured for Sync flow-through; if required, this configuration allows for a third Half-H
bridge to be controlled by PWM module 3 and also, most importantly, to remain in synchronization with
master module 1.
Figure 53. Control of Two Half-H Bridge Stages (FPWM2 = N x FPWM1)
VDC_bus
Ext SyncIn
(optional)
Master
Phase reg
En
Φ=0°
SyncIn
EPWM1A
EPWM1A
EPWM1B
CTR=zero
CTR=CMPB
X
EPWM1B
SyncOut
Slave
Phase reg
En
Φ=0°
Vout1
SyncIn
VDC_bus
EPWM2A
Vout2
EPWM2B
CTR=zero
CTR=CMPB
X
EPWM2A
SyncOut
EPWM2B
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Figure 54. Half-H Bridge Waveforms for Figure 53 (Note: Here FPWM2 = FPWM1 )
Z
I
Z
I
600
400
400
200
200
Z
CB
A
Z
I
Z
CA
CB
A
CA
EPWM1A
CA
CB
A
Z
CA
CB
A
Z
CA
CB
A
Z
EPWM1B
Pulse Center
500
500
250
Z
CB
A
250
CA
Z
CB
A
CA
EPWM2A
CA
CB
A
Z
EPWM2B
Pulse Center
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Example 11. Code Snippet for Configuration in Figure 53
//=====================================================================
// Config
//=====================================================================
// Initialization Time
//========================
// EPWM Module 1 config
EPwm1Regs.TBPRD = 600;
// Period = 1200 TBCLK counts
EPwm1Regs.TBPHS.half.TBPHS = 0;
// Set Phase register to zero
EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; // Symmetrical mode
EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE;
// Master module
EPwm1Regs.TBCTL.bit.PRDLD = TB_SHADOW;
EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_CTR_ZERO;
// Sync down-stream module
EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;
EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;
EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on CTR=Zero
EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on CTR=Zero
EPwm1Regs.AQCTLA.bit.ZRO = AQ_SET;
// set actions for EPWM1A
EPwm1Regs.AQCTLA.bit.CAU = AQ_CLEAR;
EPwm1Regs.AQCTLB.bit.ZRO = AQ_CLEAR;
// set actions for EPWM1B
EPwm1Regs.AQCTLB.bit.CAD = AQ_SET;
// EPWM Module 2 config
EPwm2Regs.TBPRD = 600;
// Period = 1200 TBCLK counts
EPwm2Regs.TBPHS.half.TBPHS = 0;
// Set Phase register to zero
EPwm2Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; // Symmetrical mode
EPwm2Regs.TBCTL.bit.PHSEN = TB_ENABLE;
// Slave module
EPwm2Regs.TBCTL.bit.PRDLD = TB_SHADOW;
EPwm2Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_IN;
// sync flow-through
EPwm2Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;
EPwm2Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;
EPwm2Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on CTR=Zero
EPwm2Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on CTR=Zero
EPwm2Regs.AQCTLA.bit.ZRO = AQ_SET;
// set actions for EPWM1A
EPwm2Regs.AQCTLA.bit.CAU = AQ_CLEAR;
EPwm2Regs.AQCTLB.bit.ZRO = AQ_CLEAR;
// set actions for EPWM1B
EPwm2Regs.AQCTLB.bit.CAD = AQ_SET;
//============================================================
EPwm1Regs.CMPA.half.CMPA = 400;
// adjust duty for output EPWM1A & EPWM1B
EPwm1Regs.CMPB = 200;
EPwm2Regs.CMPA.half.CMPA = 500;
EPwm2Regs.CMPB = 250;
3.6
// adjust point-in-time for ADCSOC trigger
// adjust duty for output EPWM2A & EPWM2B
// adjust point-in-time for ADCSOC trigger
Controlling Dual 3-Phase Inverters for Motors (ACI and PMSM)
The idea of multiple modules controlling a single power stage can be extended to the 3-phase Inverter
case. In such a case, six switching elements can be controlled using three PWM modules, one for each
leg of the inverter. Each leg must switch at the same frequency and all legs must be synchronized. A
master + two slaves configuration can easily address this requirement. Figure 55 shows how six PWM
modules can control two independent 3-phase Inverters; each running a motor.
As in the cases shown in the previous sections, we have a choice of running each inverter at a different
frequency (module 1 and module 4 are masters as in Figure 55), or both inverters can be synchronized by
using one master (module 1) and five slaves. In this case, the frequency of modules 4, 5, and 6 (all equal)
can be integer multiples of the frequency for modules 1, 2, 3 (also all equal).
78
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Figure 55. Control of Dual 3-Phase Inverter Stages as Is Commonly Used in Motor Control
Ext SyncIn
(optional)
Master
Phase reg
En
SyncIn
Φ=0°
EPWM1A
CTR=zero
CTR=CMPB
X
1
SyncOut
Slave
Phase reg
En
EPWM2A
CTR=zero
CTR=CMPB
X
2
SyncOut
EPWM2A
EPWM1A
SyncIn
Φ=0°
Slave
Phase reg
En
EPWM1B
EPWM3A
VAB
VCD
EPWM2B
VEF
EPWM1B
EPWM2B
EPWM3B
3 phase motor
SyncIn
Φ=0°
EPWM3A
CTR=zero
CTR=CMPB
X
3
SyncOut
3 phase inverter #1
EPWM3B
Slave
Phase reg
SyncIn
En
Φ=0°
EPWM4A
CTR=zero
CTR=CMPB
X
4
SyncOut
Slave
Phase reg
En
EPWM4A
SyncIn
Φ=0°
EPWM5A
EPWM6A
VAB
EPWM5A
CTR=zero
CTR=CMPB
X
5
SyncOut
Slave
Phase reg
En
EPWM4B
VCD
VEF
EPWM5B
EPWM4B
EPWM5B
EPWM6B
3 phase motor
SyncIn
Φ=0°
CTR=zero
CTR=CMPB
X
6
SyncOut
EPWM6A
3 phase inverter #2
EPWM6B
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Figure 56. 3-Phase Inverter Waveforms for Figure 55 (Only One Inverter Shown)
Z
I
Z
I
800
500
500
CA
CA
P
A
EPWM1A
CA
CA
P
A
RED
RED
EPWM1B
FED
FED
Φ2=0
600
600
CA
CA
CA
CA
EPWM2A
RED
EPWM2B
FED
700
Φ3=0
CA
EPWM3A
EPWM3B
80
700
CA
CA
CA
RED
FED
TMS320x2833x, 2823x Enhanced Pulse Width Modulator (ePWM) Module
© 2008–2009, Texas Instruments Incorporated
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Example 12. Code Snippet for Configuration in Figure 55
//=====================================================================
// Configuration
//=====================================================================
// Initialization Time
//========================// EPWM Module 1 config
EPwm1Regs.TBPRD = 800;
// Period = 1600 TBCLK counts
EPwm1Regs.TBPHS.half.TBPHS = 0;
// Set Phase register to zero
EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN;
// Symmetrical mode
EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE;
// Master module
EPwm1Regs.TBCTL.bit.PRDLD = TB_SHADOW;
EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_CTR_ZERO;
// Sync down-stream module
EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;
EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;
EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO;
// load on CTR=Zero
EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO;
// load on CTR=Zero
EPwm1Regs.AQCTLA.bit.CAU = AQ_SET;
// set actions for EPWM1A
EPwm1Regs.AQCTLA.bit.CAD = AQ_CLEAR;
EPwm1Regs.DBCTL.bit.OUT_MODE = DB_FULL_ENABLE;
// enable Dead-band module
EPwm1Regs.DBCTL.bit.POLSEL = DB_ACTV_HIC;
// Active Hi complementary
EPwm1Regs.DBFED = 50;
// FED = 50 TBCLKs
EPwm1Regs.DBRED = 50;
// RED = 50 TBCLKs
// EPWM Module 2 config
EPwm2Regs.TBPRD = 800;
// Period = 1600 TBCLK counts
EPwm2Regs.TBPHS.half.TBPHS = 0;
// Set Phase register to zero
EPwm2Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN;
// Symmetrical mode
EPwm2Regs.TBCTL.bit.PHSEN = TB_ENABLE;
// Slave module
EPwm2Regs.TBCTL.bit.PRDLD = TB_SHADOW;
EPwm2Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_IN;
// sync flow-through
EPwm2Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;
EPwm2Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;
EPwm2Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO;
// load on CTR=Zero
EPwm2Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO;
// load on CTR=Zero
EPwm2Regs.AQCTLA.bit.CAU = AQ_SET;
// set actions for EPWM2A
EPwm2Regs.AQCTLA.bit.CAD = AQ_CLEAR;
EPwm2Regs.DBCTL.bit.OUT_MODE = DB_FULL_ENABLE;
// enable Dead-band module
EPwm2Regs.DBCTL.bit.POLSEL = DB_ACTV_HIC;
// Active Hi complementary
EPwm2Regs.DBFED = 50;
// FED = 50 TBCLKs
EPwm2Regs.DBRED = 50;
// RED = 50 TBCLKs
// EPWM Module 3 config
EPwm3Regs.TBPRD = 800;
// Period = 1600 TBCLK counts
EPwm3Regs.TBPHS.half.TBPHS = 0;
// Set Phase register to zero
EPwm3Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN;
// Symmetrical mode
EPwm3Regs.TBCTL.bit.PHSEN = TB_ENABLE;
// Slave module
EPwm3Regs.TBCTL.bit.PRDLD = TB_SHADOW;
EPwm3Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_IN;
// sync flow-through
EPwm3Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;
EPwm3Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;
EPwm3Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO;
// load on CTR=Zero
EPwm3Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO;
// load on CTR=Zero
EPwm3Regs.AQCTLA.bit.CAU = AQ_SET;
// set actions for EPWM3A
EPwm3Regs.AQCTLA.bit.CAD = AQ_CLEAR;
EPwm3Regs.DBCTL.bit.OUT_MODE = DB_FULL_ENABLE;
// enable Dead-band module
EPwm3Regs.DBCTL.bit.POLSEL = DB_ACTV_HIC;
// Active Hi complementary
EPwm3Regs.DBFED = 50;
// FED = 50 TBCLKs
EPwm3Regs.DBRED = 50;
// RED = 50 TBCLKs
// Run Time (Note: Example execution of one run-time instant)
//=========================================================
EPwm1Regs.CMPA.half.CMPA = 500;
// adjust duty for output EPWM1A
EPwm2Regs.CMPA.half.CMPA = 600;
// adjust duty for output EPWM2A
EPwm3Regs.CMPA.half.CMPA = 700;
// adjust duty for output EPWM3A
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Practical Applications Using Phase Control Between PWM Modules
So far, none of the examples have made use of the phase register (TBPHS). It has either been set to zero
or its value has been a don't care. However, by programming appropriate values into TBPHS, multiple
PWM modules can address another class of power topologies that rely on phase relationship between
legs (or stages) for correct operation. As described in the TB module section, a PWM module can be
configured to allow a SyncIn pulse to cause the TBPHS register to be loaded into the TBCTR register. To
illustrate this concept, Figure 57 shows a master and slave module with a phase relationship of 120°, i.e.,
the slave leads the master.
Figure 57. Configuring Two PWM Modules for Phase Control
Ext SyncIn
(optional)
Master
Phase reg
SyncIn
En
Φ=0°
EPWM1A
EPWM1B
CTR=zero
CTR=CMPB
X
1
SyncOut
Slave
Phase reg
SyncIn
En
Φ=120°
EPWM2A
EPWM2B
CTR=zero
CTR=CMPB
X
2
SyncOut
Figure 58 shows the associated timing waveforms for this configuration. Here, TBPRD = 600 for both
master and slave. For the slave, TBPHS = 200 (i.e., 200/600 X 360° = 120°). Whenever the master
generates a SyncIn pulse (CTR = PRD), the value of TBPHS = 200 is loaded into the slave TBCTR
register so the slave time-base is always leading the master's time-base by 120°.
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Figure 58. Timing Waveforms Associated With Phase Control Between 2 Modules
FFFFh
TBCTR[0-15]
Master Module
600
600
TBPRD
0000
CTR = PRD
(SycnOut)
FFFFh
time
TBCTR[0-15]
Φ2
Phase = 120°
Slave Module
TBPRD
600
600
200
TBPHS
200
0000
SyncIn
3.8
time
Controlling a 3-Phase Interleaved DC/DC Converter
A popular power topology that makes use of phase-offset between modules is shown in Figure 59. This
system uses three PWM modules, with module 1 configured as the master. To work, the phase
relationship between adjacent modules must be F = 120°. This is achieved by setting the slave TBPHS
registers 2 and 3 with values of 1/3 and 2/3 of the period value, respectively. For example, if the period
register is loaded with a value of 600 counts, then TBPHS (slave 2) = 200 and TBPHS (slave 3) = 400.
Both slave modules are synchronized to the master 1 module.
This concept can be extended to four or more phases, by setting the TBPHS values appropriately. The
following formula gives the TBPHS values for N phases:
TBPHS(N,M) = (TBPRD/N) x (—1)
Where:
N = number of phases
M = PWM module number
For example, for the 3-phase case (N=3), TBPRD = 600,
TBPHS(3,2) = (600/3) x (2-1) = 200 (i.e., Phase value for Slave module 2)
TBPHS(3,3) = 400 (i.e., Phase value for Slave module 3)
Figure 60 shows the waveforms for the configuration in Figure 59.
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Figure 59. Control of a 3-Phase Interleaved DC/DC Converter
Ext SyncIn
(optional)
Master
Phase reg
Φ=0°
SyncIn
VIN
En
EPWM1A
EPWM1B
CTR=zero
CTR=CMPB
X
1
EPWM1A
EPWM2A
EPWM3A
EPWM1B
EPWM2B
EPWM3B
SyncOut
Slave
Phase reg
Φ=120°
SyncIn
VOUT
En
EPWM2A
EPWM2B
CTR=zero
CTR=CMPB
X
2
SyncOut
Slave
Phase reg
SyncIn
En
Φ=240°
EPWM3A
EPWM3B
CTR=zero
CTR=CMPB
X
3
84
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Figure 60. 3-Phase Interleaved DC/DC Converter Waveforms for Figure 59
Z
I
285
CA
EPWM1A
285
P
A
CA
CA
RED
P
A
FED
Z
I
CA
CA
RED
EPWM1B
300
Z
I
Z
I
450
P
A
CA
RED
FED
FED
Φ2=120°
TBPHS
(=300)
EPWM2A
EPWM2B
300
Φ2=120°
TBPHS
(=300)
EPWM3A
EPWM3B
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Example 13. Code Snippet for Configuration in Figure 59
//=====================================================================
// Config
// Initialization Time
//========================
// EPWM Module 1 config
EPwm1Regs.TBPRD = 450;
// Period = 900 TBCLK counts
EPwm1Regs.TBPHS.half.TBPHS = 0; // Set Phase register to zero
EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; // Symmetrical mode
EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE;
// Master module
EPwm1Regs.TBCTL.bit.PRDLD = TB_SHADOW;
EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_CTR_ZERO;
// Sync down-stream module
EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;
EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;
EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO;
// load on CTR=Zero
EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO;
// load on CTR=Zero
EPwm1Regs.AQCTLA.bit.CAU = AQ_SET;
// set actions for EPWM1A
EPwm1Regs.AQCTLA.bit.CAD = AQ_CLEAR;
EPwm1Regs.DBCTL.bit.OUT_MODE = DB_FULL_ENABLE;
// enable Dead-band module
EPwm1Regs.DBCTL.bit.POLSEL = DB_ACTV_HIC;
// Active Hi complementary
EPwm1Regs.DBFED = 20;
// FED = 20 TBCLKs
EPwm1Regs.DBRED = 20;
// RED = 20 TBCLKs
// EPWM Module 2 config
EPwm2Regs.TBPRD = 450;
// Period = 900 TBCLK counts
EPwm2Regs.TBPHS.half.TBPHS = 300;
// Phase = 300/900 * 360 = 120 deg
EPwm2Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; // Symmetrical mode
EPwm2Regs.TBCTL.bit.PHSEN = TB_ENABLE;
// Slave module
EPwm2Regs.TBCTL.bit.PHSDIR = TB_DOWN;
// Count DOWN on sync (=120 deg)
EPwm2Regs.TBCTL.bit.PRDLD = TB_SHADOW;
EPwm2Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_IN;
// sync flow-through
EPwm2Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;
EPwm2Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;
EPwm2Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO;
// load on CTR=Zero
EPwm2Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO;
// load on CTR=Zero
EPwm2Regs.AQCTLA.bit.CAU = AQ_SET;
// set actions for EPWM2A
EPwm2Regs.AQCTLA.bit.CAD = AQ_CLEAR;
EPwm2Regs.DBCTL.bit.OUT_MODE = DB_FULL_ENABLE;
// enable Dead-band module
EPwm2Regs.DBCTL.bit.POLSEL = DB_ACTV_HIC;
// Active Hi Complementary
EPwm2Regs.DBFED = 20;
// FED = 20 TBCLKs
EPwm2Regs.DBRED = 20;
// RED = 20 TBCLKs
// EPWM Module 3 config
EPwm3Regs.TBPRD = 450;
// Period = 900 TBCLK counts
EPwm3Regs.TBPHS.half.TBPHS = 300;
// Phase = 300/900 * 360 = 120 deg
EPwm3Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; // Symmetrical mode
EPwm3Regs.TBCTL.bit.PHSEN = TB_ENABLE;
// Slave module
EPwm2Regs.TBCTL.bit.PHSDIR = TB_UP;
// Count UP on sync (=240 deg)
EPwm3Regs.TBCTL.bit.PRDLD = TB_SHADOW;
EPwm3Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_IN;
// sync flow-through
EPwm3Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;
EPwm3Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;
EPwm3Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO;
// load on CTR=Zero
EPwm3Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO;
// load on CTR=Zero
EPwm3Regs.AQCTLA.bit.CAU = AQ_SET;
// set actions for EPWM3Ai
EPwm3Regs.AQCTLA.bit.CAD = AQ_CLEAR;
EPwm3Regs.DBCTL.bit.OUT_MODE = DB_FULL_ENABLE;
// enable Dead-band module
EPwm3Regs.DBCTL.bit.POLSEL = DB_ACTV_HIC;
// Active Hi complementary
EPwm3Regs.DBFED = 20;
// FED = 20 TBCLKs
EPwm3Regs.DBRED = 20;
// RED = 20 TBCLKs
// Run Time (Note: Example execution of one run-time instant)
//===========================================================
EPwm1Regs.CMPA.half.CMPA = 285;
// adjust duty for output EPWM1A
EPwm2Regs.CMPA.half.CMPA = 285;
// adjust duty for output EPWM2A
EPwm3Regs.CMPA.half.CMPA = 285;
// adjust duty for output EPWM3A
86
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3.9
Controlling Zero Voltage Switched Full Bridge (ZVSFB) Converter
The example given in Figure 61 assumes a static or constant phase relationship between legs (modules).
In such a case, control is achieved by modulating the duty cycle. It is also possible to dynamically change
the phase value on a cycle-by-cycle basis. This feature lends itself to controlling a class of power
topologies known as phase-shifted full bridge, or zero voltage switched full bridge. Here the controlled
parameter is not duty cycle (this is kept constant at approximately 50 percent); instead it is the phase
relationship between legs. Such a system can be implemented by allocating the resources of two PWM
modules to control a single power stage, which in turn requires control of four switching elements.
Figure 62 shows a master/slave module combination synchronized together to control a full H-bridge. In
this case, both master and slave modules are required to switch at the same PWM frequency. The phase
is controlled by using the slave's phase register (TBPHS). The master's phase register is not used and
therefore can be initialized to zero.
Figure 61. Controlling a Full-H Bridge Stage (FPWM2 = FPWM1)
Ext SyncIn
(optional)
Master
Phase reg
Φ=0°
SyncIn
En
EPWM1A
CTR=zero
CTR=CMPB
X
Slave
Phase reg
Φ=Var°
Vout
VDC_bus
EPWM1B
SyncOut
EPWM1A
EPWM2A
EPWM1B
EPWM2B
SyncIn
En
CTR=zero
CTR=CMPB
X
EPWM2A
EPWM2B
SyncOut
Var = Variable
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Figure 62. ZVS Full-H Bridge Waveforms
Z
I
Z
I
Z
I
1200
600
200
Z
CB
A
CA
Z
CB
A
CA
Z
RED
ZVS transition
EPWM1A
Power phase
FED
ZVS transition
EPWM1B
300
TBPHS
=(1200−Φ2)
Φ2=variable
CB
A
Z
CA
CB
A
Z
Z
CA
RED
EPWM2A
EPWM2B
FED
Power phase
88
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Example 14. Code Snippet for Configuration in Figure 61
//=====================================================================
// Config
//=====================================================================
// Initialization Time
//========================
// EPWM Module 1 config
EPwm1Regs.TBPRD = 1200;
// Period = 1201 TBCLK counts
EPwm1Regs.CMPA = 600;
// Set 50% fixed duty for EPWM1A
EPwm1Regs.TBPHS.half.TBPHS = 0;
// Set Phase register to zero
EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UP;
// Asymmetrical mode
EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE;
// Master module
EPwm1Regs.TBCTL.bit.PRDLD = TB_SHADOW;
EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_CTR_ZERO;
// Sync down-stream module
EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;
EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;
EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO;
// load on CTR=Zero
EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO;
// load on CTR=Zero
EPwm1Regs.AQCTLA.bit.ZRO = AQ_SET;
// set actions for EPWM1A
EPwm1Regs.AQCTLA.bit.CAU = AQ_CLEAR;
EPwm1Regs.DBCTL.bit.OUT_MODE = DB_FULL_ENABLE;
// enable Dead-band module
EPwm1Regs.DBCTL.bit.POLSEL = DB_ACTV_HIC;
// Active Hi complementary
EPwm1Regs.DBFED = 50;
// FED = 50 TBCLKs initially
EPwm1Regs.DBRED = 70;
// RED = 70 TBCLKs initially
// EPWM Module 2 config
EPwm2Regs.TBPRD = 1200;
// Period = 1201 TBCLK counts
EPwm2Regs.CMPA.half.CMPA = 600;
// Set 50% fixed duty EPWM2A
EPwm2Regs.TBPHS.half.TBPHS = 0;
// Set Phase register to zero initially
EPwm2Regs.TBCTL.bit.CTRMODE = TB_COUNT_UP;
// Asymmetrical mode
EPwm2Regs.TBCTL.bit.PHSEN = TB_ENABLE;
// Slave module
EPwm2Regs.TBCTL.bit.PRDLD = TB_SHADOW;
EPwm2Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_IN;
// sync flow-through
EPwm2Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;
EPwm2Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;
EPwm2Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO;
// load on CTR=Zero
EPwm2Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO;
// load on CTR=Zero
EPwm2Regs.AQCTLA.bit.ZRO = AQ_SET;
// set actions for EPWM2A
EPwm2Regs.AQCTLA.bit.CAU = AQ_CLEAR;
EPwm2Regs.DBCTL.bit.OUT_MODE = DB_FULL_ENABLE;
// enable Dead-band module
EPwm2Regs.DBCTL.bit.POLSEL = DB_ACTV_HIC;
// Active Hi complementary
EPwm2Regs.DBFED = 30;
// FED = 30 TBCLKs initially
EPwm2Regs.DBRED = 40;
// RED = 40 TBCLKs initially
// Run Time (Note: Example execution of one run-time instant)
//============================================================
EPwm2Regs.TBPHS = 1200-300;
// Set Phase reg to 300/1200 * 360 = 90 deg
EPwm1Regs.DBFED = FED1_NewValue;
// Update ZVS transition interval
EPwm1Regs.DBRED = RED1_NewValue;
// Update ZVS transition interval
EPwm2Regs.DBFED = FED2_NewValue;
// Update ZVS transition interval
EPwm2Regs.DBRED = RED2_NewValue;
// Update ZVS transition interval
EPwm1Regs.CMPB = 200;
// adjust point-in-time for ADCSOC trigger
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Registers
This chapter includes the register layouts and bit description for the submodules.
4.1
Time-Base Submodule Registers
Figure 63 through Figure 67 and Table 21 through Table 25 provide the time-base register definitions.
Figure 63. Time-Base Period Register (TBPRD)
15
0
TBPRD
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 21. Time-Base Period Register (TBPRD) Field Descriptions
Bits
Name
Value
15-0
TBPRD
0000- These bits determine the period of the time-base counter. This sets the PWM frequency.
FFFFh
Shadowing of this register is enabled and disabled by the TBCTL[PRDLD] bit. By default this register
is shadowed.
• If TBCTL[PRDLD] = 0, then the shadow is enabled and any write or read will automatically go to
the shadow register. In this case, the active register will be loaded from the shadow register
when the time-base counter equals zero.
• If TBCTL[PRDLD] = 1, then the shadow is disabled and any write or read will go directly to the
active register, that is the register actively controlling the hardware.
• The active and shadow registers share the same memory map address.
Description
Figure 64. Time-Base Phase Register (TBPHS)
15
0
TBPHS
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 22. Time-Base Phase Register (TBPHS) Field Descriptions
Bits
Name
15-0
TBPHS
Value
Description
0000-FFFF These bits set time-base counter phase of the selected ePWM relative to the time-base that is
supplying the synchronization input signal.
• If TBCTL[PHSEN] = 0, then the synchronization event is ignored and the time-base counter is
not loaded with the phase.
• If TBCTL[PHSEN] = 1, then the time-base counter (TBCTR) will be loaded with the phase
(TBPHS) when a synchronization event occurs. The synchronization event can be initiated by
the input synchronization signal (EPWMxSYNCI) or by a software forced synchronization.
Figure 65. Time-Base Counter Register (TBCTR)
15
0
TBCTR
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 23. Time-Base Counter Register (TBCTR) Field Descriptions
Bits
Name
Value
Description
15-0
TBCTR
0000FFFF
Reading these bits gives the current time-base counter value.
Writing to these bits sets the current time-base counter value. The update happens as soon as the
write occurs; the write is NOT synchronized to the time-base clock (TBCLK) and the register is not
shadowed.
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Figure 66. Time-Base Control Register (TBCTL)
15
14
13
12
10
9
8
FREE, SOFT
PHSDIR
CLKDIV
HSPCLKDIV
R/W-0
R/W-0
R/W-0
R/W-0,0,1
7
6
3
2
HSPCLKDIV
SWFSYNC
5
SYNCOSEL
4
PRDLD
PHSEN
1
CTRMODE
0
R/W-0,0,1
R/W-0
R/W-0
R/W-0
R/W-0
R/W-11
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 24. Time-Base Control Register (TBCTL) Field Descriptions
Bit
15:14
Field
Value
FREE, SOFT
Description
Emulation Mode Bits. These bits select the behavior of the ePWM time-base counter during
emulation events:
00
Stop after the next time-base counter increment or decrement
01
Stop when counter completes a whole cycle:
• Up-count mode: stop when the time-base counter = period (TBCTR = TBPRD)
• Down-count mode: stop when the time-base counter = 0x0000 (TBCTR = 0x0000)
• Up-down-count mode: stop when the time-base counter = 0x0000 (TBCTR = 0x0000)
1X
13
PHSDIR
Free run
Phase Direction Bit.
This bit is only used when the time-base counter is configured in the up-down-count mode. The
PHSDIR bit indicates the direction the time-base counter (TBCTR) will count after a synchronization
event occurs and a new phase value is loaded from the phase (TBPHS) register. This is
irrespective of the direction of the counter before the synchronization event..
In the up-count and down-count modes this bit is ignored.
12:10
0
Count down after the synchronization event.
1
Count up after the synchronization event.
CLKDIV
Time-base Clock Prescale Bits
These bits determine part of the time-base clock prescale value.
TBCLK = SYSCLKOUT / (HSPCLKDIV × CLKDIV)
9:7
000
/1 (default on reset)
001
/2
010
/4
011
/8
100
/16
101
/32
110
/64
111
/128
HSPCLKDIV
High Speed Time-base Clock Prescale Bits
These bits determine part of the time-base clock prescale value.
TBCLK = SYSCLKOUT / (HSPCLKDIV × CLKDIV)
This divisor emulates the HSPCLK in the TMS320x281x system as used on the Event Manager
(EV) peripheral.
000
/1
001
/2 (default on reset)
010
/4
011
/6
100
/8
101
/10
110
/12
111
/14
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Table 24. Time-Base Control Register (TBCTL) Field Descriptions (continued)
Bit
6
Field
Value
SWFSYNC
Description
Software Forced Synchronization Pulse
0
Writing a 0 has no effect and reads always return a 0.
1
Writing a 1 forces a one-time synchronization pulse to be generated.
This event is ORed with the EPWMxSYNCI input of the ePWM module.
SWFSYNC is valid (operates) only when EPWMxSYNCI is selected by SYNCOSEL = 00.
5:4
3
SYNCOSEL
Synchronization Output Select. These bits select the source of the EPWMxSYNCO signal.
00
EPWMxSYNC:
01
CTR = zero: Time-base counter equal to zero (TBCTR = 0x0000)
10
CTR = CMPB : Time-base counter equal to counter-compare B (TBCTR = CMPB)
11
Disable EPWMxSYNCO signal
PRDLD
Active Period Register Load From Shadow Register Select
0
The period register (TBPRD) is loaded from its shadow register when the time-base counter,
TBCTR, is equal to zero.
A write or read to the TBPRD register accesses the shadow register.
1
Load the TBPRD register immediately without using a shadow register.
A write or read to the TBPRD register directly accesses the active register.
2
1:0
PHSEN
Counter Register Load From Phase Register Enable
0
Do not load the time-base counter (TBCTR) from the time-base phase register (TBPHS)
1
Load the time-base counter with the phase register when an EPWMxSYNCI input signal occurs or
when a software synchronization is forced by the SWFSYNC bit
CTRMODE
Counter Mode
The time-base counter mode is normally configured once and not changed during normal operation.
If you change the mode of the counter, the change will take effect at the next TBCLK edge and the
current counter value shall increment or decrement from the value before the mode change.
These bits set the time-base counter mode of operation as follows:
92
00
Up-count mode
01
Down-count mode
10
Up-down-count mode
11
Stop-freeze counter operation (default on reset)
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Figure 67. Time-Base Status Register (TBSTS)
15
8
Reserved
R-0
7
2
1
0
Reserved
3
CTRMAX
SYNCI
CTRDIR
R-0
R/W1C-0
R/W1C-0
R-1
LEGEND: R/W = Read/Write; R = Read only; R/W1C = Read/Write 1 to clear; -n = value after reset
Table 25. Time-Base Status Register (TBSTS) Field Descriptions
Bit
Field
Value
Description
15:3
Reserved
Reserved
2
CTRMAX
Time-Base Counter Max Latched Status Bit
1
0
0
Reading a 0 indicates the time-base counter never reached its maximum value. Writing a 0 will
have no effect.
1
Reading a 1 on this bit indicates that the time-base counter reached the max value 0xFFFF. Writing
a 1 to this bit will clear the latched event.
SYNCI
Input Synchronization Latched Status Bit
0
Writing a 0 will have no effect. Reading a 0 indicates no external synchronization event has
occurred.
1
Reading a 1 on this bit indicates that an external synchronization event has occurred
(EPWMxSYNCI). Writing a 1 to this bit will clear the latched event.
CTRDIR
Time-Base Counter Direction Status Bit. At reset, the counter is frozen; therefore, this bit has no
meaning. To make this bit meaningful, you must first set the appropriate mode via
TBCTL[CTRMODE].
0
Time-Base Counter is currently counting down.
1
Time-Base Counter is currently counting up.
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Counter-Compare Submodule Registers
Figure 68 through Figure 70 and Table 26 through Table 28 illustrate the counter-compare submodule
control and status registers.
Figure 68. Counter-Compare A Register (CMPA)
15
0
CMPA
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 26. Counter-Compare A Register (CMPA) Field Descriptions
Bits
Name
Description
15-0
CMPA
The value in the active CMPA register is continuously compared to the time-base counter (TBCTR). When
the values are equal, the counter-compare module generates a "time-base counter equal to counter
compare A" event. This event is sent to the action-qualifier where it is qualified and converted it into one
or more actions. These actions can be applied to either the EPWMxA or the EPWMxB output depending
on the configuration of the AQCTLA and AQCTLB registers. The actions that can be defined in the
AQCTLA and AQCTLB registers include:
• Do nothing; the event is ignored.
• Clear: Pull the EPWMxA and/or EPWMxB signal low
• Set: Pull the EPWMxA and/or EPWMxB signal high
• Toggle the EPWMxA and/or EPWMxB signal
Shadowing of this register is enabled and disabled by the CMPCTL[SHDWAMODE] bit. By default this
register is shadowed.
• If CMPCTL[SHDWAMODE] = 0, then the shadow is enabled and any write or read will automatically
go to the shadow register. In this case, the CMPCTL[LOADAMODE] bit field determines which event
will load the active register from the shadow register.
• Before a write, the CMPCTL[SHDWAFULL] bit can be read to determine if the shadow register is
currently full.
• If CMPCTL[SHDWAMODE] = 1, then the shadow register is disabled and any write or read will go
directly to the active register, that is the register actively controlling the hardware.
• In either mode, the active and shadow registers share the same memory map address.
Figure 69. Counter-Compare B Register (CMPB)
15
0
CMPB
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
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Table 27. Counter-Compare B Register (CMPB) Field Descriptions
Bits
Name
Description
15-0
CMPB
The value in the active CMPB register is continuously compared to the time-base counter (TBCTR). When
the values are equal, the counter-compare module generates a "time-base counter equal to counter
compare B" event. This event is sent to the action-qualifier where it is qualified and converted it into one
or more actions. These actions can be applied to either the EPWMxA or the EPWMxB output depending
on the configuration of the AQCTLA and AQCTLB registers. The actions that can be defined in the
AQCTLA and AQCTLB registers include:
• Do nothing. event is ignored.
• Clear: Pull the EPWMxA and/or EPWMxB signal low
• Set: Pull the EPWMxA and/or EPWMxB signal high
• Toggle the EPWMxA and/or EPWMxB signal
Shadowing of this register is enabled and disabled by the CMPCTL[SHDWBMODE] bit. By default this
register is shadowed.
• If CMPCTL[SHDWBMODE] = 0, then the shadow is enabled and any write or read will automatically
go to the shadow register. In this case, the CMPCTL[LOADBMODE] bit field determines which event
will load the active register from the shadow register:
• Before a write, the CMPCTL[SHDWBFULL] bit can be read to determine if the shadow register is
currently full.
• If CMPCTL[SHDWBMODE] = 1, then the shadow register is disabled and any write or read will go
directly to the active register, that is the register actively controlling the hardware.
• In either mode, the active and shadow registers share the same memory map address.
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Figure 70. Counter-Compare Control Register (CMPCTL)
15
10
9
8
Reserved
SHDWBFULL
SHDWAFULL
R-0
R-0
R-0
1
0
7
6
5
4
3
2
Reserved
SHDWBMODE
Reserved
SHDWAMODE
LOADBMODE
LOADAMODE
R-0
R/W-0
R-0
R/W-0
R/W-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 28. Counter-Compare Control Register (CMPCTL) Field Descriptions
Bits
15-10
9
Name
Value
Description
Reserved
Reserved
SHDWBFULL
Counter-compare B (CMPB) Shadow Register Full Status Flag
This bit self clears once a load-strobe occurs.
8
0
CMPB shadow FIFO not full yet
1
Indicates the CMPB shadow FIFO is full; a CPU write will overwrite current shadow value.
SHDWAFULL
Counter-compare A (CMPA) Shadow Register Full Status Flag
The flag bit is set when a 32-bit write to CMPA:CMPAHR register or a 16-bit write to CMPA
register is made. A 16-bit write to CMPAHR register will not affect the flag.
This bit self clears once a load-strobe occurs.
CMPA shadow FIFO not full yet
1
Indicates the CMPA shadow FIFO is full, a CPU write will overwrite the current shadow
value.
7
Reserved
Reserved
6
SHDWBMODE
Counter-compare B (CMPB) Register Operating Mode
5
Reserved
4
SHDWAMODE
3-2
1-0
96
0
0
Shadow mode. Operates as a double buffer. All writes via the CPU access the shadow
register.
1
Immediate mode. Only the active compare B register is used. All writes and reads directly
access the active register for immediate compare action.
Reserved
Counter-compare A (CMPA) Register Operating Mode
0
Shadow mode. Operates as a double buffer. All writes via the CPU access the shadow
register.
1
Immediate mode. Only the active compare register is used. All writes and reads directly
access the active register for immediate compare action
LOADBMODE
Active Counter-Compare B (CMPB) Load From Shadow Select Mode
This bit has no effect in immediate mode (CMPCTL[SHDWBMODE] = 1).
00
Load on CTR = Zero: Time-base counter equal to zero (TBCTR = 0x0000)
01
Load on CTR = PRD: Time-base counter equal to period (TBCTR = TBPRD)
10
Load on either CTR = Zero or CTR = PRD
11
Freeze (no loads possible)
LOADAMODE
Active Counter-Compare A (CMPA) Load From Shadow Select Mode.
This bit has no effect in immediate mode (CMPCTL[SHDWAMODE] = 1).
00
Load on CTR = Zero: Time-base counter equal to zero (TBCTR = 0x0000)
01
Load on CTR = PRD: Time-base counter equal to period (TBCTR = TBPRD)
10
Load on either CTR = Zero or CTR = PRD
11
Freeze (no loads possible)
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Figure 71. Compare A High Resolution Register (CMPAHR)
15
8
CMPAHR
R/W-0
7
0
Reserved
R-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 29. Compare A High Resolution Register (CMPAHR) Field Descriptions
Bit
15-8
Field
Value
CMPAHR
00-FFh These 8-bits contain the high-resolution portion (least significant 8-bits) of the counter-compare A
value. CMPA:CMPAHR can be accessed in a single 32-bit read/write.
Description
Shadowing is enabled and disabled by the CMPCTL[SHDWAMODE] bit as described for the CMPA
register.
7-0
4.3
Reserved
Reserved for TI Test
Action-Qualifier Submodule Registers
Figure 72 through Figure 75 and Table 30 through Table 33 provide the action-qualifier submodule
register definitions.
Figure 72. Action-Qualifier Output A Control Register (AQCTLA)
15
12
7
11
10
9
8
Reserved
CBD
CBU
R-0
R/W-0
R/W-0
6
5
4
3
2
1
0
CAD
CAU
PRD
ZRO
R/W-0
R/W-0
R/W-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 30. Action-Qualifier Output A Control Register (AQCTLA) Field Descriptions
Bits
Name
Value Description
15-12
Reserved
Reserved
11-10
CBD
Action when the time-base counter equals the active CMPB register and the counter is
decrementing.
9-8
7-6
00
Do nothing (action disabled)
01
Clear: force EPWMxA output low.
10
Set: force EPWMxA output high.
11
Toggle EPWMxA output: low output signal will be forced high, and a high signal will be forced low.
CBU
Action when the counter equals the active CMPB register and the counter is incrementing.
00
Do nothing (action disabled)
01
Clear: force EPWMxA output low.
10
Set: force EPWMxA output high.
11
Toggle EPWMxA output: low output signal will be forced high, and a high signal will be forced low.
CAD
Action when the counter equals the active CMPA register and the counter is decrementing.
00
Do nothing (action disabled)
01
Clear: force EPWMxA output low.
10
Set: force EPWMxA output high.
11
Toggle EPWMxA output: low output signal will be forced high, and a high signal will be forced low.
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Table 30. Action-Qualifier Output A Control Register (AQCTLA) Field Descriptions (continued)
Bits
Name
5-4
CAU
3-2
Value Description
Action when the counter equals the active CMPA register and the counter is incrementing.
00
Do nothing (action disabled)
01
Clear: force EPWMxA output low.
10
Set: force EPWMxA output high.
11
Toggle EPWMxA output: low output signal will be forced high, and a high signal will be forced low.
PRD
Action when the counter equals the period.
Note: By definition, in count up-down mode when the counter equals period the direction is defined
as 0 or counting down.
1-0
00
Do nothing (action disabled)
01
Clear: force EPWMxA output low.
10
Set: force EPWMxA output high.
11
Toggle EPWMxA output: low output signal will be forced high, and a high signal will be forced low.
ZRO
Action when counter equals zero.
Note: By definition, in count up-down mode when the counter equals 0 the direction is defined as 1
or counting up.
00
Do nothing (action disabled)
01
Clear: force EPWMxA output low.
10
Set: force EPWMxA output high.
11
Toggle EPWMxA output: low output signal will be forced high, and a high signal will be forced low.
Figure 73. Action-Qualifier Output B Control Register (AQCTLB)
15
12
7
11
10
9
8
Reserved
CBD
CBU
R-0
R/W-0
R/W-0
6
5
4
3
2
1
0
CAD
CAU
PRD
ZRO
R/W-0
R/W-0
R/W-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 31. Action-Qualifier Output B Control Register (AQCTLB) Field Descriptions
Bits
Reserved
11-10
CBD
9-8
7-6
98
Name
15-12
Value Description
Action when the counter equals the active CMPB register and the counter is decrementing.
00
Do nothing (action disabled)
01
Clear: force EPWMxB output low.
10
Set: force EPWMxB output high.
11
Toggle EPWMxB output: low output signal will be forced high, and a high signal will be forced low.
CBU
Action when the counter equals the active CMPB register and the counter is incrementing.
00
Do nothing (action disabled)
01
Clear: force EPWMxB output low.
10
Set: force EPWMxB output high.
11
Toggle EPWMxB output: low output signal will be forced high, and a high signal will be forced low.
CAD
Action when the counter equals the active CMPA register and the counter is decrementing.
00
Do nothing (action disabled)
01
Clear: force EPWMxB output low.
10
Set: force EPWMxB output high.
11
Toggle EPWMxB output: low output signal will be forced high, and a high signal will be forced low.
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Table 31. Action-Qualifier Output B Control Register (AQCTLB) Field Descriptions (continued)
Bits
Name
5-4
CAU
3-2
Value Description
Action when the counter equals the active CMPA register and the counter is incrementing.
00
Do nothing (action disabled)
01
Clear: force EPWMxB output low.
10
Set: force EPWMxB output high.
11
Toggle EPWMxB output: low output signal will be forced high, and a high signal will be forced low.
PRD
Action when the counter equals the period.
Note: By definition, in count up-down mode when the counter equals period the direction is defined
as 0 or counting down.
1-0
00
Do nothing (action disabled)
01
Clear: force EPWMxB output low.
10
Set: force EPWMxB output high.
11
Toggle EPWMxB output: low output signal will be forced high, and a high signal will be forced low.
ZRO
Action when counter equals zero.
Note: By definition, in count up-down mode when the counter equals 0 the direction is defined as 1
or counting up.
00
Do nothing (action disabled)
01
Clear: force EPWMxB output low.
10
Set: force EPWMxB output high.
11
Toggle EPWMxB output: low output signal will be forced high, and a high signal will be forced low.
Figure 74. Action-Qualifier Software Force Register (AQSFRC)
15
8
Reserved
R-0
7
6
5
4
3
2
1
0
RLDCSF
OTSFB
ACTSFB
OTSFA
ACTSFA
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 32. Action-Qualifier Software Force Register (AQSFRC) Field Descriptions
Bit
Field
15:8
Reserved
7:6
RLDCSF
5
Value
Description
AQCSFRC Active Register Reload From Shadow Options
00
Load on event counter equals zero
01
Load on event counter equals period
10
Load on event counter equals zero or counter equals period
11
Load immediately (the active register is directly accessed by the CPU and is not loaded from the
shadow register).
OTSFB
One-Time Software Forced Event on Output B
0
Writing a 0 (zero) has no effect. Always reads back a 0
This bit is auto cleared once a write to this register is complete, i.e., a forced event is initiated.)
This is a one-shot forced event. It can be overridden by another subsequent event on output B.
1
Initiates a single s/w forced event
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Table 32. Action-Qualifier Software Force Register (AQSFRC) Field Descriptions (continued)
Bit
Field
4:3
ACTSFB
Value
Description
Action when One-Time Software Force B Is invoked
00
Does nothing (action disabled)
01
Clear (low)
10
Set (high)
11
Toggle (Low -> High, High -> Low)
Note: This action is not qualified by counter direction (CNT_dir)
2
OTSFA
One-Time Software Forced Event on Output A
0
Writing a 0 (zero) has no effect. Always reads back a 0.
This bit is auto cleared once a write to this register is complete ( i.e., a forced event is initiated).
1
1:0
ACTSFA
Initiates a single software forced event
Action When One-Time Software Force A Is Invoked
00
Does nothing (action disabled)
01
Clear (low)
10
Set (high)
11
Toggle (Low → High, High → Low)
Note: This action is not qualified by counter direction (CNT_dir)
Figure 75. Action-Qualifier Continuous Software Force Register (AQCSFRC)
15
8
Reserved
R-0
7
4
3
2
1
0
Reserved
CSFB
CSFA
R-0
R/W-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 33. Action-qualifier Continuous Software Force Register (AQCSFRC) Field Descriptions
Bits
Name
15-4
Reserved
Value
Description
Reserved
3-2
CSFB
Continuous Software Force on Output B
In immediate mode, a continuous force takes effect on the next TBCLK edge.
In shadow mode, a continuous force takes effect on the next TBCLK edge after a shadow load into
the active register. To configure shadow mode, use AQSFRC[RLDCSF].
1-0
00
Forcing disabled, i.e., has no effect
01
Forces a continuous low on output B
10
Forces a continuous high on output B
11
Software forcing is disabled and has no effect
CSFA
Continuous Software Force on Output A
In immediate mode, a continuous force takes effect on the next TBCLK edge.
In shadow mode, a continuous force takes effect on the next TBCLK edge after a shadow load into
the active register.
00
Forcing disabled, i.e., has no effect
01
Forces a continuous low on output A
10
Forces a continuous high on output A
11
Software forcing is disabled and has no effect
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4.4
Dead-Band Submodule Registers
through Figure 78 and through Table 36 provide the register definitions.
Figure 76. Dead-Band Generator Control Register (DBCTL)
15
8
Reserved
R-0
7
6
5
4
3
2
1
0
Reserved
IN_MODE
POLSEL
OUT_MODE
R-0
R/W-0
R/W-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
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Table 34. Dead-Band Generator Control Register (DBCTL) Field Descriptions
Bits
Name
Value
Description
15-6
Reserved
Reserved
5-4
IN_MODE
Dead Band Input Mode Control
Bit 5 controls the S5 switch and bit 4 controls the S4 switch shown in Figure 31.
This allows you to select the input source to the falling-edge and rising-edge delay.
To produce classical dead-band waveforms the default is EPWMxA In is the source for both
falling and rising-edge delays.
00
EPWMxA In (from the action-qualifier) is the source for both falling-edge and rising-edge
delay.
01
EPWMxB In (from the action-qualifier) is the source for rising-edge delayed signal.
EPWMxA In (from the action-qualifier) is the source for falling-edge delayed signal.
10
EPWMxA In (from the action-qualifier) is the source for rising-edge delayed signal.
EPWMxB In (from the action-qualifier) is the source for falling-edge delayed signal.
11
3-2
POLSEL
EPWMxB In (from the action-qualifier) is the source for both rising-edge delay and
falling-edge delayed signal.
Polarity Select Control
Bit 3 controls the S3 switch and bit 2 controls the S2 switch shown in Figure 31.
This allows you to selectively invert one of the delayed signals before it is sent out of the
dead-band submodule.
The following descriptions correspond to classical upper/lower switch control as found in one
leg of a digital motor control inverter.
These assume that DBCTL[OUT_MODE] = 1,1 and DBCTL[IN_MODE] = 0,0. Other
enhanced modes are also possible, but not regarded as typical usage modes.
1-0
00
Active high (AH) mode. Neither EPWMxA nor EPWMxB is inverted (default).
01
Active low complementary (ALC) mode. EPWMxA is inverted.
10
Active high complementary (AHC). EPWMxB is inverted.
11
Active low (AL) mode. Both EPWMxA and EPWMxB are inverted.
OUT_MODE
Dead-band Output Mode Control
Bit 1 controls the S1 switch and bit 0 controls the S0 switch shown in Figure 31.
This allows you to selectively enable or bypass the dead-band generation for the falling-edge
and rising-edge delay.
00
Dead-band generation is bypassed for both output signals. In this mode, both the EPWMxA
and EPWMxB output signals from the action-qualifier are passed directly to the PWM-chopper
submodule.
In this mode, the POLSEL and IN_MODE bits have no effect.
01
Disable rising-edge delay. The EPWMxA signal from the action-qualifier is passed straight
through to the EPWMxA input of the PWM-chopper submodule.
The falling-edge delayed signal is seen on output EPWMxB. The input signal for the delay is
determined by DBCTL[IN_MODE].
10
The rising-edge delayed signal is seen on output EPWMxA. The input signal for the delay is
determined by DBCTL[IN_MODE].
Disable falling-edge delay. The EPWMxB signal from the action-qualifier is passed straight
through to the EPWMxB input of the PWM-chopper submodule.
11
102
Dead-band is fully enabled for both rising-edge delay on output EPWMxA and falling-edge
delay on output EPWMxB. The input signal for the delay is determined by DBCTL[IN_MODE].
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Figure 77. Dead-Band Generator Rising Edge Delay Register (DBRED)
15
10
9
8
Reserved
DEL
R-0
R/W-0
7
0
DEL
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 35. Dead-Band Generator Rising Edge Delay Register (DBRED) Field Descriptions
Bits
Name
15-10
9-0
Value Description
Reserved
Reserved
DEL
Rising Edge Delay Count. 10-bit counter.
Figure 78. Dead-Band Generator Falling Edge Delay Register (DBFED)
15
10
9
8
Reserved
DEL
R-0
R/W-0
7
0
DEL
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 36. Dead-Band Generator Falling Edge Delay Register (DBFED) Field Descriptions
Bits
15-10
9-0
4.5
Name
Description
Reserved
Reserved
DEL
Falling Edge Delay Count. 10-bit counter
PWM-Chopper Submodule Control Register
Figure 79 and Table 37 provide the definitions for the PWM-chopper submodule control register.
Figure 79. PWM-Chopper Control Register (PCCTL)
15
11
7
10
8
Reserved
CHPDUTY
R-0
R/W-0
5
4
1
0
CHPFREQ
OSHTWTH
CHPEN
R/W-0
R/W-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
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Table 37. PWM-Chopper Control Register (PCCTL) Bit Descriptions
Bits
15-11
Reserved
10-8
CHPDUTY
7:5
4:1
0
104
Name
Value
Description
Reserved
Chopping Clock Duty Cycle
000
Duty = 1/8 (12.5%)
001
Duty = 2/8 (25.0%)
010
Duty = 3/8 (37.5%)
011
Duty = 4/8 (50.0%)
100
Duty = 5/8 (62.5%)
101
Duty = 6/8 (75.0%)
110
Duty = 7/8 (87.5%)
111
Reserved
CHPFREQ
Chopping Clock Frequency
000
Divide by 1 (no prescale, = 12.5 MHz at 100 MHz SYSCLKOUT)
001
Divide by 2 (6.25 MHz at 100 MHz SYSCLKOUT)
010
Divide by 3 (4.16 MHz at 100 MHz SYSCLKOUT)
011
Divide by 4 (3.12 MHz at 100 MHz SYSCLKOUT)
100
Divide by 5 (2.50 MHz at 100 MHz SYSCLKOUT)
101
Divide by 6 (2.08 MHz at 100 MHz SYSCLKOUT)
110
Divide by 7 (1.78 MHz at 100 MHz SYSCLKOUT)
111
Divide by 8 (1.56 MHz at 100 MHz SYSCLKOUT)
OSHTWTH
One-Shot Pulse Width
0000
1 x SYSCLKOUT / 8 wide ( = 80 nS at 100 MHz SYSCLKOUT)
0001
2 x SYSCLKOUT / 8 wide ( = 160 nS at 100 MHz SYSCLKOUT)
0010
3 x SYSCLKOUT / 8 wide ( = 240 nS at 100 MHz SYSCLKOUT)
0011
4 x SYSCLKOUT / 8 wide ( = 320 nS at 100 MHz SYSCLKOUT)
0100
5 x SYSCLKOUT / 8 wide ( = 400 nS at 100 MHz SYSCLKOUT)
0101
6 x SYSCLKOUT / 8 wide ( = 480 nS at 100 MHz SYSCLKOUT)
0110
7 x SYSCLKOUT / 8 wide ( = 560 nS at 100 MHz SYSCLKOUT)
0111
8 x SYSCLKOUT / 8 wide ( = 640 nS at 100 MHz SYSCLKOUT)
1000
9 x SYSCLKOUT / 8 wide ( = 720 nS at 100 MHz SYSCLKOUT)
1001
10 x SYSCLKOUT / 8 wide ( = 800 nS at 100 MHz SYSCLKOUT)
1010
11 x SYSCLKOUT / 8 wide ( = 880 nS at 100 MHz SYSCLKOUT)
1011
12 x SYSCLKOUT / 8 wide ( = 960 nS at 100 MHz SYSCLKOUT)
1100
13 x SYSCLKOUT / 8 wide ( = 1040 nS at 100 MHz SYSCLKOUT)
1101
14 x SYSCLKOUT / 8 wide ( = 1120 nS at 100 MHz SYSCLKOUT)
1110
15 x SYSCLKOUT / 8 wide ( = 1200 nS at 100 MHz SYSCLKOUT)
1111
16 x SYSCLKOUT / 8 wide ( = 1280 nS at 100 MHz SYSCLKOUT)
CHPEN
PWM-chopping Enable
0
Disable (bypass) PWM chopping function
1
Enable chopping function
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4.6
Trip-Zone Submodule Control and Status Registers
Figure 80. Trip-Zone Select Register (TZSEL)
15
14
13
12
11
10
9
8
Reserved
OSHT6
OSHT5
OSHT4
OSHT3
OSHT2
OSHT1
R-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
5
4
3
2
1
0
7
6
Reserved
CBC6
CBC5
CBC4
CBC3
CBC2
CBC1
R-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 38. Trip-Zone Submodule Select Register (TZSEL) Field Descriptions
Bits
Name
Value
Description
One-Shot (OSHT) Trip-zone enable/disable. When any of the enabled pins go low, a one-shot trip event occurs for this
ePWM module. When the event occurs, the action defined in the TZCTL register () is taken on the EPWMxA and EPWMxB
outputs. The one-shot trip condition remains latched until the user clears the condition via the TZCLR register ().
15:14
13
12
11
10
9
8
Reserved
Reserved
OSHT6
Trip-zone 6 (TZ6) Select
0
Disable TZ6 as a one-shot trip source for this ePWM module.
1
Enable TZ6 as a one-shot trip source for this ePWM module.
OSHT5
Trip-zone 5 (TZ5) Select
0
Disable TZ5 as a one-shot trip source for this ePWM module
1
Enable TZ5 as a one-shot trip source for this ePWM module
OSHT4
Trip-zone 4 (TZ4) Select
0
Disable TZ4 as a one-shot trip source for this ePWM module
1
Enable TZ4 as a one-shot trip source for this ePWM module
OSHT3
Trip-zone 3 (TZ3) Select
0
Disable TZ3 as a one-shot trip source for this ePWM module
1
Enable TZ3 as a one-shot trip source for this ePWM module
OSHT2
Trip-zone 2 (TZ2) Select
0
Disable TZ2 as a one-shot trip source for this ePWM module
1
Enable TZ2 as a one-shot trip source for this ePWM module
OSHT1
Trip-zone 1 (TZ1) Select
0
Disable TZ1 as a one-shot trip source for this ePWM module
1
Enable TZ1 as a one-shot trip source for this ePWM module
Cycle-by-Cycle (CBC) Trip-zone enable/disable. When any of the enabled pins go low, a cycle-by-cycle trip event occurs
for this ePWM module. When the event occurs, the action defined in the TZCTL register () is taken on the EPWMxA and
EPWMxB outputs. A cycle-by-cycle trip condition is automatically cleared when the time-base counter reaches zero.
7:6
5
4
3
2
Reserved
Reserved
CBC6
Trip-zone 6 (TZ6) Select
0
Disable TZ6 as a CBC trip source for this ePWM module
1
Enable TZ6 as a CBC trip source for this ePWM module
CBC5
Trip-zone 5 (TZ5) Select
0
Disable TZ5 as a CBC trip source for this ePWM module
1
Enable TZ5 as a CBC trip source for this ePWM module
CBC4
Trip-zone 4 (TZ4) Select
0
Disable TZ4 as a CBC trip source for this ePWM module
1
Enable TZ4 as a CBC trip source for this ePWM module
CBC3
Trip-zone 3 (TZ3) Select
0
Disable TZ3 as a CBC trip source for this ePWM module
1
Enable TZ3 as a CBC trip source for this ePWM module
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Table 38. Trip-Zone Submodule Select Register (TZSEL) Field Descriptions (continued)
Bits
Name
1
CBC2
0
Value
Description
Trip-zone 2 (TZ2) Select
0
Disable TZ2 as a CBC trip source for this ePWM module
1
Enable TZ2 as a CBC trip source for this ePWM module
CBC1
Trip-zone 1 (TZ1) Select
0
Disable TZ1 as a CBC trip source for this ePWM module
1
Enable TZ1 as a CBC trip source for this ePWM module
Figure 81. Trip-Zone Control Register (TZCTL)
15
8
Reserved
R-0
7
4
3
2
1
0
Reserved
TZB
TZA
R-0
R/W-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 39. Trip-Zone Control Register (TZCTL) Field Descriptions
Bits
Name
15–4
Reserved
Reserved
3–2
TZB
When a trip event occurs the following action is taken on output EPWMxB. Which trip-zone pins
can cause an event is defined in the TZSEL register.
1–0
Value
Description
00
High impedance (EPWMxB = High-impedance state)
01
Force EPWMxB to a high state
10
Force EPWMxB to a low state
11
Do nothing, no action is taken on EPWMxB.
TZA
When a trip event occurs the following action is taken on output EPWMxA. Which trip-zone pins
can cause an event is defined in the TZSEL register.
00
High impedance (EPWMxA = High-impedance state)
01
Force EPWMxA to a high state
10
Force EPWMxA to a low state
11
Do nothing, no action is taken on EPWMxA.
Figure 82. Trip-Zone Enable Interrupt Register (TZEINT)
15
8
Reserved
R -0
7
2
1
0
Reserved
3
OST
CBC
Reserved
R-0
R/W-0
R/W-0
R-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 40. Trip-Zone Enable Interrupt Register (TZEINT) Field Descriptions
Bits
Name
15-3
Reserved
2
Value
Description
Reserved
OST
Trip-zone One-Shot Interrupt Enable
0
Disable one-shot interrupt generation
1
Enable Interrupt generation; a one-shot trip event will cause a EPWMx_TZINT PIE interrupt.
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Table 40. Trip-Zone Enable Interrupt Register (TZEINT) Field Descriptions (continued)
Bits
1
Name
Value
Description
CBC
0
Trip-zone Cycle-by-Cycle Interrupt Enable
0
Disable cycle-by-cycle interrupt generation.
1
Enable interrupt generation; a cycle-by-cycle trip event will cause an EPWMx_TZINT PIE
interrupt.
Reserved
Reserved
Figure 83. Trip-Zone Flag Register (TZFLG)
15
8
Reserved
R-0
7
2
1
0
Reserved
3
OST
CBC
INT
R-0
R-0
R-0
R-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 41. Trip-Zone Flag Register (TZFLG) Field Descriptions
Bits
Name
15-3
Reserved
2
Value Description
Reserved
OST
Latched Status Flag for A One-Shot Trip Event
0
No one-shot trip event has occurred.
1
Indicates a trip event has occurred on a pin selected as a one-shot trip source.
This bit is cleared by writing the appropriate value to the TZCLR register.
1
CBC
Latched Status Flag for Cycle-By-Cycle Trip Event
0
No cycle-by-cycle trip event has occurred.
1
Indicates a trip event has occurred on a pin selected as a cycle-by-cycle trip source. The
TZFLG[CBC] bit will remain set until it is manually cleared by the user. If the cycle-by-cycle trip
event is still present when the CBC bit is cleared, then CBC will be immediately set again. The
specified condition on the pins is automatically cleared when the ePWM time-base counter
reaches zero (TBCTR = 0x0000) if the trip condition is no longer present. The condition on the
pins is only cleared when the TBCTR = 0x0000 no matter where in the cycle the CBC flag is
cleared.
This bit is cleared by writing the appropriate value to the TZCLR register.
0
INT
Latched Trip Interrupt Status Flag
0
Indicates no interrupt has been generated.
1
Indicates an EPWMx_TZINT PIE interrupt was generated because of a trip condition.
No further EPWMx_TZINT PIE interrupts will be generated until this flag is cleared. If the
interrupt flag is cleared when either CBC or OST is set, then another interrupt pulse will be
generated. Clearing all flag bits will prevent further interrupts.
This bit is cleared by writing the appropriate value to the TZCLR register ().
Figure 84. Trip-Zone Clear Register (TZCLR)
15
8
Reserved
R-0
7
2
1
0
Reserved
3
OST
CBC
INT
R-0
R/W-0
R/W-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
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Table 42. Trip-Zone Clear Register (TZCLR) Field Descriptions
Bits
Name
15-3
Reserved
2
1
0
Value
Description
Reserved
OST
Clear Flag for One-Shot Trip (OST) Latch
0
Has no effect. Always reads back a 0.
1
Clears this Trip (set) condition.
CBC
Clear Flag for Cycle-By-Cycle (CBC) Trip Latch
0
Has no effect. Always reads back a 0.
1
Clears this Trip (set) condition.
INT
Global Interrupt Clear Flag
0
Has no effect. Always reads back a 0.
1
Clears the trip-interrupt flag for this ePWM module (TZFLG[INT]).
NOTE: No further EPWMx_TZINT PIE interrupts will be generated until the flag is cleared. If
the TZFLG[INT] bit is cleared and any of the other flag bits are set, then another interrupt
pulse will be generated. Clearing all flag bits will prevent further interrupts.
Figure 85. Trip-Zone Force Register (TZFRC)
15
8
Reserved
R-0
7
2
1
0
Reserved
3
OST
CBC
Reserved
R-0
R/W-0
R/W-0
R- 0
LEGEND: R/W = Read/Write; R = Read only; -n = value after resetonly an hour
Table 43. Trip-Zone Force Register (TZFRC) Field Descriptions
Bits
Name
15- 3
Reserved
2
1
0
4.7
Value
Description
Reserved
OST
Force a One-Shot Trip Event via Software
0
Writing of 0 is ignored. Always reads back a 0.
1
Forces a one-shot trip event and sets the TZFLG[OST] bit.
CBC
Force a Cycle-by-Cycle Trip Event via Software
0
Writing of 0 is ignored. Always reads back a 0.
1
Forces a cycle-by-cycle trip event and sets the TZFLG[CBC] bit.
Reserved
Reserved
Event-Trigger Submodule Registers
The event trigger selection register (ETSEL) and field descriptions below describe the registers for the
event-trigger submodule.
Figure 86. Event-Trigger Selection Register (ETSEL)
15
14
12
11
10
8
SOCBEN
SOCBSEL
SOCAEN
SOCASEL
R/W-0
R/W-0
R/W-0
R/W-0
7
4
3
2
0
Reserved
INTEN
INTSEL
R-0
R/W-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
108
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Table 44. Event-Trigger Selection Register (ETSEL) Field Descriptions
Bits
15
14-12
Name
Value
Description
SOCBEN
Enable the ADC Start of Conversion B (EPWMxSOCB) Pulse
0
Disable EPWMxSOCB.
1
Enable EPWMxSOCB pulse.
SOCBSEL
EPWMxSOCB Selection Options
These bits determine when a EPWMxSOCB pulse will be generated.
11
10-8
000
Reserved
001
Enable event time-base counter equal to zero. (TBCTR = 0x0000)
010
Enable event time-base counter equal to period (TBCTR = TBPRD)
011
Reserved
100
Enable event time-base counter equal to CMPA when the timer is incrementing.
101
Enable event time-base counter equal to CMPA when the timer is decrementing.
110
Enable event: time-base counter equal to CMPB when the timer is incrementing.
111
Enable event: time-base counter equal to CMPB when the timer is decrementing.
SOCAEN
Enable the ADC Start of Conversion A (EPWMxSOCA) Pulse
0
Disable EPWMxSOCA.
1
Enable EPWMxSOCA pulse.
SOCASEL
EPWMxSOCA Selection Options
These bits determine when a EPWMxSOCA pulse will be generated.
7-4
3
000
Reserved
001
Enable event time-base counter equal to zero. (TBCTR = 0x0000)
010
Enable event time-base counter equal to period (TBCTR = TBPRD)
011
Reserved
100
Enable event time-base counter equal to CMPA when the timer is incrementing.
101
Enable event time-base counter equal to CMPA when the timer is decrementing.
110
Enable event: time-base counter equal to CMPB when the timer is incrementing.
111
Enable event: time-base counter equal to CMPB when the timer is decrementing.
Reserved
Reserved
INTEN
2-0
Enable ePWM Interrupt (EPWMx_INT) Generation
0
Disable EPWMx_INT generation
1
Enable EPWMx_INT generation
INTSEL
ePWM Interrupt (EPWMx_INT) Selection Options
000
Reserved
001
Enable event time-base counter equal to zero. (TBCTR = 0x0000)
010
Enable event time-base counter equal to period (TBCTR = TBPRD)
011
Reserved
100
Enable event time-base counter equal to CMPA when the timer is incrementing.
101
Enable event time-base counter equal to CMPA when the timer is decrementing.
110
Enable event: time-base counter equal to CMPB when the timer is incrementing.
111
Enable event: time-base counter equal to CMPB when the timer is decrementing.
Figure 87. Event-Trigger Prescale Register (ETPS)
15
14
13
12
11
10
9
8
SOCBCNT
SOCBPRD
SOCACNT
SOCAPRD
R-0
R/W-0
R-0
R/W-0
7
4
3
2
1
0
Reserved
INTCNT
INTPRD
R-0
R-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
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Table 45. Event-Trigger Prescale Register (ETPS) Field Descriptions
Bits
15-14
Name
Description
SOCBCNT
ePWM ADC Start-of-Conversion B Event (EPWMxSOCB) Counter Register
These bits indicate how many selected ETSEL[SOCBSEL] events have occurred:
13-12
00
No events have occurred.
01
1 event has occurred.
10
2 events have occurred.
11
3 events have occurred.
SOCBPRD
ePWM ADC Start-of-Conversion B Event (EPWMxSOCB) Period Select
These bits determine how many selected ETSEL[SOCBSEL] events need to occur before an
EPWMxSOCB pulse is generated. To be generated, the pulse must be enabled
(ETSEL[SOCBEN] = 1). The SOCB pulse will be generated even if the status flag is set from
a previous start of conversion (ETFLG[SOCB] = 1). Once the SOCB pulse is generated, the
ETPS[SOCBCNT] bits will automatically be cleared.
11-10
00
Disable the SOCB event counter. No EPWMxSOCB pulse will be generated
01
Generate the EPWMxSOCB pulse on the first event: ETPS[SOCBCNT] = 0,1
10
Generate the EPWMxSOCB pulse on the second event: ETPS[SOCBCNT] = 1,0
11
Generate the EPWMxSOCB pulse on the third event: ETPS[SOCBCNT] = 1,1
SOCACNT
ePWM ADC Start-of-Conversion A Event (EPWMxSOCA) Counter Register
These bits indicate how many selected ETSEL[SOCASEL] events have occurred:
9-8
00
No events have occurred.
01
1 event has occurred.
10
2 events have occurred.
11
3 events have occurred.
SOCAPRD
ePWM ADC Start-of-Conversion A Event (EPWMxSOCA) Period Select
These bits determine how many selected ETSEL[SOCASEL] events need to occur before an
EPWMxSOCA pulse is generated. To be generated, the pulse must be enabled
(ETSEL[SOCAEN] = 1). The SOCA pulse will be generated even if the status flag is set from
a previous start of conversion (ETFLG[SOCA] = 1). Once the SOCA pulse is generated, the
ETPS[SOCACNT] bits will automatically be cleared.
00
Disable the SOCA event counter. No EPWMxSOCA pulse will be generated
01
Generate the EPWMxSOCA pulse on the first event: ETPS[SOCACNT] = 0,1
10
Generate the EPWMxSOCA pulse on the second event: ETPS[SOCACNT] = 1,0
11
Generate the EPWMxSOCA pulse on the third event: ETPS[SOCACNT] = 1,1
7-4
Reserved
Reserved
3-2
INTCNT
ePWM Interrupt Event (EPWMx_INT) Counter Register
These bits indicate how many selected ETSEL[INTSEL] events have occurred. These bits are
automatically cleared when an interrupt pulse is generated. If interrupts are disabled,
ETSEL[INT] = 0 or the interrupt flag is set, ETFLG[INT] = 1, the counter will stop counting
events when it reaches the period value ETPS[INTCNT] = ETPS[INTPRD].
00
No events have occurred.
01
1 event has occurred.
10
2 events have occurred.
11
3 events have occurred.
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Table 45. Event-Trigger Prescale Register (ETPS) Field Descriptions (continued)
Bits
Name
Description
1-0
INTPRD
ePWM Interrupt (EPWMx_INT) Period Select
These bits determine how many selected ETSEL[INTSEL] events need to occur before an
interrupt is generated. To be generated, the interrupt must be enabled (ETSEL[INT] = 1). If
the interrupt status flag is set from a previous interrupt (ETFLG[INT] = 1) then no interrupt will
be generated until the flag is cleared via the ETCLR[INT] bit. This allows for one interrupt to
be pending while another is still being serviced. Once the interrupt is generated, the
ETPS[INTCNT] bits will automatically be cleared.
Writing a INTPRD value that is the same as the current counter value will trigger an interrupt
if it is enabled and the status flag is clear.
Writing a INTPRD value that is less than the current counter value will result in an undefined
state.
If a counter event occurs at the same instant as a new zero or non-zero INTPRD value is
written, the counter is incremented.
00
Disable the interrupt event counter. No interrupt will be generated and ETFRC[INT] is
ignored.
01
Generate an interrupt on the first event INTCNT = 01 (first event)
10
Generate interrupt on ETPS[INTCNT] = 1,0 (second event)
11
Generate interrupt on ETPS[INTCNT] = 1,1 (third event)
Figure 88. Event-Trigger Flag Register (ETFLG)
15
8
Reserved
R-0
7
3
2
1
0
Reserved
4
SOCB
SOCA
Reserved
INT
R-0
R-0
R-0
R-0
R-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 46. Event-Trigger Flag Register (ETFLG) Field Descriptions
Bits
Name
15-4
Reserved
3
2
Value
Description
Reserved
SOCB
Latched ePWM ADC Start-of-Conversion B (EPWMxSOCB) Status Flag
0
Indicates no EPWMxSOCB event occurred
1
Indicates that a start of conversion pulse was generated on EPWMxSOCB. The
EPWMxSOCB output will continue to be generated even if the flag bit is set.
SOCA
Latched ePWM ADC Start-of-Conversion A (EPWMxSOCA) Status Flag
Unlike the ETFLG[INT] flag, the EPWMxSOCA output will continue to pulse even if the flag bit
is set.
1
Reserved
0
INT
0
Indicates no event occurred
1
Indicates that a start of conversion pulse was generated on EPWMxSOCA. The
EPWMxSOCA output will continue to be generated even if the flag bit is set.
Reserved
Latched ePWM Interrupt (EPWMx_INT) Status Flag
0
Indicates no event occurred
1
Indicates that an ePWMx interrupt (EWPMx_INT) was generated. No further interrupts will be
generated until the flag bit is cleared. Up to one interrupt can be pending while the
ETFLG[INT] bit is still set. If an interrupt is pending, it will not be generated until after the
ETFLG[INT] bit is cleared. Refer to Figure 44.
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Figure 89. Event-Trigger Clear Register (ETCLR)
15
8
Reserved
R=0
7
3
2
1
0
Reserved
4
SOCB
SOCA
Reserved
INT
R-0
R/W-0
R/W-0
R-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 47. Event-Trigger Clear Register (ETCLR) Field Descriptions
Bits
Name
15-4
Reserved
3
2
Value
Description
Reserved
SOCB
ePWM ADC Start-of-Conversion B (EPWMxSOCB) Flag Clear Bit
0
Writing a 0 has no effect. Always reads back a 0
1
Clears the ETFLG[SOCB] flag bit
SOCA
ePWM ADC Start-of-Conversion A (EPWMxSOCA) Flag Clear Bit
1
Reserved
0
INT
0
Writing a 0 has no effect. Always reads back a 0
1
Clears the ETFLG[SOCA] flag bit
Reserved
ePWM Interrupt (EPWMx_INT) Flag Clear Bit
0
Writing a 0 has no effect. Always reads back a 0
1
Clears the ETFLG[INT] flag bit and enable further interrupts pulses to be generated
Figure 90. Event-Trigger Force Register (ETFRC)
15
8
Reserved
R-0
7
4
3
2
1
0
Reserved
SOCB
SOCA
Reserved
INT
R-0
R/W-0
R/W-0
R-0
R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 48. Event-Trigger Force Register (ETFRC) Field Descriptions
Bits
Name
15-4
Reserved
Reserved
SOCB
SOCB Force Bit. The SOCB pulse will only be generated if the event is enabled in the
ETSEL register. The ETFLG[SOCB] flag bit will be set regardless.
3
2
Value
0
Has no effect. Always reads back a 0.
1
Generates a pulse on EPWMxSOCB and sets the SOCBFLG bit. This bit is used for test
purposes.
SOCA
1
Reserved
0
INT
Description
SOCA Force Bit. The SOCA pulse will only be generated if the event is enabled in the
ETSEL register. The ETFLG[SOCA] flag bit will be set regardless.
0
Writing 0 to this bit will be ignored. Always reads back a 0.
1
Generates a pulse on EPWMxSOCA and set the SOCAFLG bit. This bit is used for test
purposes.
0
Reserved
INT Force Bit. The interrupt will only be generated if the event is enabled in the ETSEL
register. The INT flag bit will be set regardless.
0
Writing 0 to this bit will be ignored. Always reads back a 0.
1
Generates an interrupt on EPWMxINT and set the INT flag bit. This bit is used for test
purposes.
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4.8
Proper Interrupt Initialization Procedure
When the ePWM peripheral clock is enabled it may be possible that interrupt flags may be set due to
spurious events due to the ePWM registers not being properly initialized. The proper procedure for
initializing the ePWM peripheral is as follows:
1. Disable global interrupts (CPU INTM flag)
2. Disable ePWM interrupts
3. Set TBCLKSYNC=0
4. Initialize peripheral registers
5. Set TBCLKSYNC=1
6. Clear any spurious ePWM flags (including PIEIFR)
7. Enable ePWM interrupts
8. Enable global interrupts
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Appendix A Revision History
This document has been revised to include the following technical change(s).
Table 49. Changes for this Revision
114
Location
Modifications, Additions, and Deletions
Section 2.2.3.2
Added this section (Time-Base Clock Synchronization)
Global
Changed all occurrences of TBCNT to TBCTR
Global
Changed all occurrences of DBCTL.bit.MODE to DBCTL.bit.OUT_MODE
Section 4.8
Added to the sequence list
Figure 90
Changed R-0 for bits 0, 2, 3 to R/W-0
Revision History
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