DM5414/DM6414 12-bit DAS

DM5414/DM6414

12-bit DAS-module

User's Manual

Real Time Devices Finland Oy

Hardware Release 2.0


Lepolantie 14

FIN-00660 Helsinki, Finland

Tel: (+358) 9 346 4538

Fax: (+358) 9 346 4539

Email: [email protected]

URL: www.rtdfinland.fi

DM5414/DM6414 RTD Finland Oy 1998-2001

I I S O 9 0 0 1 a n d A S 9 1 0 0 C e r t i f f i e d

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IMPORTANT

Although this information contained in this manual has been carefully verified, RTD Finland Oy assumes no responsibility for errors that may appear in this manual, or for any damage to things or persons resulting from improper use of this manual or of the related software. RTD Finland Oy reserves the right to change the contents and for of this manual, as well as the features and specifications of this product at any time, without notice.

Published by


Lepolantie 14

FIN-00660 Helsinki, Finland

Copyright © 1995/2001 by RTD Finland Oy

All rights reserved

Printed in Finland


Table of Contents

===============================================================

INTRODUCTION

Analog-to-Digital conversion

Digital-to-Analog conversion

8254 Timer/Counter

Digital I/O

Mechanical description

Connector description

What comes with your board

Board accessories

Application software and drivers

Hardware accessories

Using this manual

When you need help

CHAPTER 1 - BOARD SETTINGS

Factory-Configured Jumper Settings

Base Address Jumpers

8254 Timer Counter Sources

Interrupt Channel select

External 5V Reference Type : Tracking (Ratiometric) / Absolute

D/A - converter range select (Channels 1,2 and 3,4)

D/A - converter channel polarity select (Channels 1,2 and 3,4)

Internal 2,5V / External Reference selection for A/D-converter

CHAPTER 2 - BOARD INSTALLATION

Board installation

External I/O connections

Primary 50-pin Analog Digital Expansion Connector

Secondary 50-pin Analog Digital Expansion Connector

Connecting the analog input pins

Connecting the analog outputs

Connecting the Timer/Counters and digital I/O

CHAPTER 3 - HARDWARE DESCRIPTION

A/D conversion circuitry

Reprint of LM12458 DAS-Chip datasheet

D/A conversion circuitry

Timer/Counters

Digital I/O, Advanced Bit Programmable Digital I/O

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CHAPTER 4 - BOARD OPERATION AND PROGRAMMING

Defining the I/O map

Onboard Peripherals

Base+20

Base+21

Base+22

Base+23

DAS chip enable

DAC chip enable/Load DAC's

Reserved

Software trigger

(write)

(write/read)

(write)

Overlay bit = 0

Base+24

Base+25

Base+26

Base+27

8254 Timer/Counter 0

8254 Timer/Counter 1

(write/read)

(write/read)

8254 Timer/Counter 2 (write/read)

8254 Timer/Counter Control byte (write)

Overlay bit = 1

Base+24

Base+25

Base+26

Base+27

Port 0 Data

Port 1 Data

Port 0 Control byte

Digital Chip Control byte

(write/read)

(write/read)

(write/read)

(write)

Base+29

Base+2A

Base+2B

DAC 2 Register

DAC 3 Register

DAC 4 Register

(write)

(write)

(write)

(write)

Base+2C

Base+2D

Base+2E

Base+2F

Board Setup Register 1 (read)

Board Setup Register 2

16-bit digital I/O port

(read)

(write/read)

Reserved


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Each of the DAS Chips

RAM Pointer 00

Base+0

Base+1

Base+2

Instruction 0

Parameter field for Instruction 0

Instruction 1

Base+3

Base+4

Base+5


Instruction 2


.

Base+E Instruction 15

Base+F Parameter field for Instruction 15

RAM Pointer 01

.

Base+0

Base+1

Base+2

Base+3

Base+E

Base+F

1 Comparison Limit 0

1 Polarity of Comp intr/ Sign of Limit 0





RAM Pointer 10

Base+0

Base+1

Base+2

Base+3

.

Base+E

Base+F







Base+10

Base+11

Base+12

Base+13

Base+14

Base+15

Base+16

Base+17

Base+18

Base+19

Base+1A

Base+1B

DAS Configuration Register 1

DAS Configuration Register 2

DAS Interrupt mask Register 1

DAS Interrupt mask Register 2

DAS Interrupt Enable Register 1

DAS Interrupt Enable Register 2

DAS Timer Register 1

DAS Timer Register 2

DAS Conversion FIFO low Byte

DAS Conversion FIFO high Byte

DAS Limit 1 Status Register

DAS Limit 2 Status Register


Programming the DM5414

Clearing and setting bits in a port

A/D conversions

Interrupts

What is an interrupt?

Interrupt request lines

8259 Programmable interrupt controller

Interrupt mask register (IMR)

End-Of-Interrupt (EOI) Command

What exactly happens when an interrupt occurs?

Using interrupts in your program

Writing an interrupt service routine (ISR)

Saving the startup IMR and interrupt vector

Common Interrupt mistakes

D/A Conversions

Timer/Counters

Digital I/O

APPENDIX A DM5414/DM6414 Specifications

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List of Illustrations

===============================================================

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INTRODUCTION

===============================================================

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The DM6414 analog digital dataModule® will turn your PC/104 cpuModule™ or other PC/104 computer into a low power multifunction high performance data acquisition and control system. This user's manual describes the operation of the DM5414/DM6414 PC/104

Analog/Digital Interface board.

Some of the key properties of the DM5414/DM6414 include:

* 32 single ended or 16 differential analog input channels

* 4 independent 12-bit low power A/D chips with 87 ksample throughput

* 0-2.5V or 0-5V input ranges

* Each A/D chip features: Data acquisition sequencer

32 sample conversion FIFO

16-bit Data acquisition timer

Window comparators

Auto calibration

* Software enabled interrupts

* SYNC in and SYNC out for parallel sampling of up to 4 channels per board

* 16 Digital I/O: 8 bit programmable direction, 8 port programmable direction

* 16 Digital I/O: latched 8 Out, 8 in

* Three 8254 based 16 bit Timer/Counters free for the user

* Four 12-bit D/A channels with dedicated grounds

*

±

5V,

±

10V, 0

−

5V, 0

−

10V Volt output ranges

* Single +5V operation

* Support for direct PC/104 interface with all RTD dataModules™ and front end boards.

* PC/104 compliant form factor

* DM5414 is XT bus, DM6414 is AT bus version

* RTD IDAN frame compatible

The following paragraphs briefly describe the major features of the DM5414. A more detailed discussion is included in Chapter 3 (Hardware description) and in Chapter 4 (Board operation and programming. The board setup is described in Chapter 1 (Board Settings).

Analog-to-Digital Conversion

The Analog-to-Digital circuitry consists of 4 independent 12-bit + sign integrated

A/D-converters. These converters function independently of each other and can have different setups, acquisition speeds and input ranges. The analog input channels are divided between two 50-pin expansion connectors. Channels 1-16 are located on the "Primary" connector (J3) ; channels 17-32 are located on the "Secondary" connector (J4). The analog input channels are dedicated to the 4 A/D converter chips called DAS1, DAS2, DAS3, DAS4.

DAS1

DAS2

DAS3

DAS4

Channels 1-8

Channels 9-16

Channels 17-24

Channels 25-32


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Any two channels on one DAS chip can be configured for a differential input configuration. This means Channels 1 and 31 cannot work together in differential mode , but 1 and 5 can.The input voltage ranges 0-2.5V and 0-5V can be selected for each DAS-chip. This setup is done using "solder shorts" on the bottom side of the board (see Fig. 1-12). The 5V reference can be selected with jumpers from two sources: 1) A 5,0V absolute reference or 2) The analog

5V supply of the chip. Option 2 will provide ratiometric operation of the DAS-chips. The 5V source selection is global for all the DAS-chips (see Fig. 1-7).

The onboard DAS-chips can be software programmed for different resolutions: These include: 9 or 12 bit + sign conversions. 9 bit conversions are much faster than 12 bit conversions.

µ throughput rate at 12 bits + sign is 100k samples / second.

Conversions are controlled by the Data acquisitions sequencers on the DAS-chips.

Each conversion can be configured independently and the sequencer program runs automatically sampling data into the onchip FIFO's with no CPU interference. Conversion parameters include window comparator monitoring, conversion resolution, acquisition delay etc. The features available for controlling each conversion in random order provides very powerful data acquisition performance.

The converted data can be transferred to PC-memory in two ways. Data can be transferred using the programmed I/O mode or the interrupt mode. A special Interrupt mode using the REP

INS (Repeat Input String) instruction supports very fast throughput rates. By generating an interrupt when the FIFO is half full, a REP INS instruction can be executed, transferring data to the PC memory and emptying the DAS FIFO at maximum rate allowed on the data bus. The mode of transfer is selected from software.

Digital-to-Analog Conversions

The Digial-to Analog (D/A) circuitry features four independent 12-bit analog output channles with jumper selectable output ranges of 0V to 5V, 0V to 10V, 5V, 10V. Data is programmed into the D/A converter by writing two 8 bit bytes, the LSB and the MSB. The LSB contains the lower 8 data bits (0..7) and the MSB contains the higher data bits (8..11). The D/A converter latches can be loaded (updated) in parallel with a "Load" command.


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8254 Timer/Counters

One 8254 programmable Timer/Counter provides three independent 16-bit timer counters, to support a wide range of timing and counting functions. The source for the timer/counters can be the onboard 8 MHz clock or an external oscillator. The timers T0 and T1 can be cascaded to generate a synchronizing signal to clock all the DAS-chips in parallel, or the output of these timers can be connected to an external IRQ-line. The 8254 timer / counter is not needed to set the acquisition speed of the DAS-chips since they have internal 16-bit timer counters to do this.

Digital I/O

The DM5414 has 16 latched TTL/CMOS general purpose digital I/O available in the secondary expansion connector J4. These ports have 8 outputs in "port C "- lines and 8 inputs in

"port A"- lines. The input port has onboard 47K pulldown resistors. These ports are not bit addressable.

16 buffered TTL/CMOS lines are also available grouped as eight independent, bit programmable lines in Port 0, and an 8-bit programmable port at Port 1. The bit-programmable lines support RTD's two Advanced Digital Interrupt modes. An interrupt flag can be set when any bit changes value (event interrupt) or when the lines match a programmed value (match interrupt).

For either mode masking can be used to monitor selected lines. Port 0 is pulled low with 47K pulldown resistors.

Mechanical description

The DM5414 is designed on a PC/104 form factor. An easy mechanical interface to both

PC/104 and EUROCARD systems can be achieved. Stack your PC/104 compatible computer directly on the DM5414 using the onboard mounting holes. DM5414 is XT bus, DM6414 is an

AT bus board version. The DM6414 also can be installed in the RTD IDAN modular aluminium enclosure system either in a single or double high frame.

Connector description

There are two 50 pin analog/digital interface connectors on the DM5414 to directly interface to I/O signals. The signal definition of these connectors is compatible with the analogdigital PC/104 dataModules™ manufactured by RTD.


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What comes with your board

You receive the following items in your DM5414 package:

* DM5414 interface module with stackthrough bus connector

* Software and diagnostics diskette with C source code

* User's manual

If any item is missing or damaged, please call Real Time Devices Finland Customer

Service Department at (+358) 9 346 4538.

Board accessories

In addition to the items included in your DM5414 delivery several software and hardware accessories are available. Call your distributor for more information on these accessories and for help in choosing the best items to support your instrumentation system.

* Application programs and drivers

* Hardware accessories

Real Time Devices can supply a complete set of accessories to your DM5414/DM6414 card. These include IDAN enclosures, power supplies, signal conditioning modules, terminal boards and other interconnection systems.

Using this manual

This manual is intended to help you install your new DM5414 card and get it running quickly, while also providing enough detail about the board and it's functions so that you can enjoy maximum use of it's features even in the most demanding applications. We assume you already have an understanding of basic data acquisition principles.

When you need help

This manual and all the example programs will provide you with enough information to fully utilize all the features on this board. If you have any problems installing or using this board, contact our Technical Support Department (+358) 9 346 4538 during European business hours, or send a FAX requesting assistance to (+358) 9 346 4539. When sending a FAX request, please include your company's name and address, your name, your telephone number, and a brief description of the problem.


CHAPTER 1 - BOARD SETTINGS

===============================================================

The DM5414 have jumper settings you can change if necessary to suit your application. The module is factory-configured as listed in the table and shown on the layout diagram in the beginning of this chapter. Should you need to change the module settings, use these easy-to-follow instructions before you stack your module into your

PC/104 system.

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Factory-Configured Jumper settings

Table 1-1 lists the factory settings of the user configurable jumper settings on the

DM5414/DM6414 board. Figures 1-1 and 1-2 show the board layout and the location of the factory-set jumpers. The following paragraphs explain how to change these settings. Pay special attention to the settings of the base address jumpers to avoid address contention when you first use your module in your system.

Table 1-1 Factory Settings

Jumper

Function Controlled (jmp#) Factory Settings (Jumpers installed)

BA Base Address (2) 1A0h (both not installed)

TIMERS Clock source for counters (11) CNT0 OSC, CNT1 OT0, (Timers cascaded)

IRQ #1 Timer/Counter Interrupt (4) Disabled (Not selected)

IRQ #2 DAS Interrupt (4)

IRQ #3 PPI Interrupt (4)

IRQ 5

Disabled (Not selected)

B2 DAS +5V REF source (1) Ratiometric (Connected to analog 5V, solder blob)

DA1_R DA-chip 1 range select (2) Set to 10V range (J7)




DA1_P DA-channel 1 Bip/Unip (2) Set to bipolar range (J7)




B5 DAS1 REF 2.5/5.0 (3) Set to 2.5V (Solder connection bottom side)

B3

B6

B1

DAS2 REF 2.5/5.0 (3)

DAS3 REF 2.5/5.0 (3)

DAS4 REF 2.5/5.0 (3)

Set to 2.5V (Solder connection bottom side)



Table 1-1 Factory configured jumper settings


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Fig 1-1 DM6414 Board Layout showing Factory-Configured settings


This page is left intentionally blank

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BA - Base Address (Factory Setting: 1A0h)

The most common cause of failure when you are first setting up your module is address contention. Some of your computers I/O space is already occupied by other internal I/O devices and expansion boards. When the DM5414 attempts to use it's reserved I/O addresses already used by another peripheral device, erratic performance may occur and data read from the board may be corrupted.

To avoid this problem make sure you set up the base address first using the two jumpers which let you choose from 4 different I/O addresses in your computers I/O. Should the factory installed setting of 1A0h be unusable for your system configuration, you may change this setting to another using the options illustrated in Table 1-2. The table shows the switch settings and their corresponding values in hexadecimal values. Make sure you verify the correct location of the base address jumpers. Jumper #3 is located below jumper #4 with the PC/104 bus connector toward the bottom. When the jumper is removed it corresponds to a logical "0", connecting the jumper to a "1". When you set the base address of the module, record the setting in the table inside the back cover of this manual after the Appendices.

Table 1-2 Base Address Jumper #3 , #4 settings

Table 1-2 Base Address Jumpers

Address in HEX Address in Decimal

1A0h 416d

280h 640d

300h

380h

768d

896d

0 = Jumper removed, 1 = Jumper closed

Jumpers

X3 = 0 , X4 = 0

X3 = 1 , X4 = 0

X3 = 0 , X4 = 1

X3 = 1 , X4 = 1

Fig. 1-3 Base address jumpers

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TIMERS Clock sources for Timer /Counters

(Factory settings: CLK0-OSC,CLK1-OT0,CLK2-OT2)

The jumpers shown in figure 1-4, let you select the clock sources for the 8254 based timer/counters, TC0, TC1, and TC2. The factory setting cascades all the three counter/timers, with the clock source for TC0 being the onboard 8 MHz oscillator, the output of TC0 providing the clock for TC1, and the output of TC1 providing the clock for TC2. You can connect TC0 and TC2 clock sources to an external clock through the "Primary" external I/O-expansion connector J3 or you can set TC0 and TC2 to be clocked by the onboard 8 MHz oscillator. Fig.

1-5 shows a block diagram of the counter/timer circuitry to help you with these connections.

The SYNC jumper field connects the source for the SYNC pins of the AD converter chips.

All the SYNC pins of the AD converters are connected together and selected with this jumper field

NOTE: When installing jumpers on this header, make sure that only one jumper is installed in each group of the CLK pins.

Fig. 1-4 8254 Counter/Timer Clock Source Jumpers, Labels are not present on

the board due to lack of space.


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Fig 1-5 User Timer/Counter Circuit diagram

IRQ#1 Timer Interrupt Channel select

(Factory settings: Interrupt Channel Disabled)

IRQ#2 DAS Interrupt Channel select

(Factory settings: Interrupt #5)

IRQ#3 Timer Interrupt Channel select

(Factory settings: Interrupt Channel Disabled)

The header connectors shown in Figure 1-6, lets you connect the output of board interrupt sources to an interrupt channel. To activate a channel, you must install a jumper vertically across the desired IRQ channel's pins.

To determine which DAS-chip has caused an interrupt and on what condition , you must read the interrupt status registers (BASE+14 and BASE+15) of each DAS chip with enabled interrupts. Reading these registers will clear all interrupt flags of the interrupt status register of the DAS-chip. All the 4 DAS-chips are connected together to one external interrupt request line with (positive) OR-logic. If any of the 4 chips has a active interrupt condition it's interrupt request line will keep the global DAS-IRQ line active. This also means any of the chips may assert the interrupt request. If you have enabled interrupts on multiple chips, you must read the interrupt status registers of all the chips with enabled interrupts when a DAS- interrupt occurs. Failure to


Page 19 do so may keep the interrupt request line active (high) because one of the DAS chips may still have a pending (non-serviced) interrupt condition.

Note: The IRQ lines are grouped as follows from left to right:

IRQ11, IRQ10, IRQ7, IRQ5

Fig. 1-6 Interrupt line factory setting, DAS interrupt set at IRQ5.

Other interrupts are disabled.

REF DAS +5V Reference source selection

(Factory settings: Ratiometric)

The DAS chips 5V input voltage range can use two reference techniques:

1. Absolute reference, where a precision 5,00V reference is used at the Vref+

and GND to Vref-.

2. Ratiometric reference, where the analog supply (5V) is connected to the Vref+

and GND to Vref-.

In ratiometric systems, the analog input voltage is proportional to the one used for the A/D - converters reference voltage. When this is the system analog power supply, it relaxes the system reference requirements since the analog input voltage and the

A/D - converter reference voltage change together. This maintains the same input code for the same conditions.


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Figure 1-7 shows the 5V reference source selection solder blob B2. This setting is

global for all the DAS-chips. And set to ratiometric factory installed.

D/A - converter range select (Channels 1,2 and 3,4)

DA1_R

DA2_R

DA3_R

DA4_R

DA-chip 1 range select




DA1_R

DA2_R

D/A-converter Range selection (Factory settings: 10V)


The jumper field J7 configures D/A channel #1 while J8 configures channel #2.

These jumper blocks are located next to the primary expansion connector J3. Figure 1-8

illustrates the range jumper for D/A - channels 1 and 2.

Figure 1-8a Range jumper for D/A - channels #1 and #2 set for 10V range.


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Figure 1-8b Range jumper for D/A - channels #1 and #2 set for 5V range.

DA3_R

DA4_R



The jumper field J5 configures D/A channel #3 while J6 configures channel #4.

These jumper blocks are located next to the primary expansion connector J4. Figure 1-9

illustrates the range jumper for D/A - channels 3 and 4.

Figure 1-9a Range jumper for D/A - channels #3 and #4 set for 10V range.


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Figure 1-9b Range jumper for D/A - channels #3 and #4 set for 5V range.

D/A - converter channel polarity select (Channels 1,2 and 3,4)

DA1_P

DA2_P

DA3_P

DA4_P

DA-channel 1 Bip/Unip




DA1_P

DA2_P

D/A-converter channel 1 Polarity selection (Factory setting: bipolar)


The jumpers in jumper fields J7 and J8 select the polarity of the D/A converter channels

1 and 2. Available selections are unipolar or bipolar. For example if you have selected the range to be 10V and you set the polarity to bipolar you will achieve a -10V to +10V output range. Similarly if your range is set to 5V and you select unipolar you have a

0 to 5V output range.

Figure 1-10a Bipolar operation on D/A channels 1 and 2.

Figure 1-10b Unipolar operation on D/A channels 1 and 2


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DA3_P

DA4_P



The jumpers in jumper fields J5 and J6 select the polarity of the D/A converter channels

3 and 4. Available selections are unipolar or bipolar. For example if you have selected the range to be 10V and you set the polarity to bipolar you will achieve a -10V to +10V output range. Similarly if your range is set to 5V and you select unipolar you have a

0 to 5V output range.

Figure 1-11a Bipolar operation on D/A channels 3 and 4.

Figure 1-11b Unipolar operation on D/A channels 3 and 4


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B5 DAS1 Reference selection (Factory setting: 2.5V)




The input range can be set individually for each DAS - chip. A three terminal solder jumper selects the range to be either 0 - 2.5V or 0 - 5.0V. These solder jumpers are located on the solder side (under side) of your DM5414. They are grouped so that the range solder jumper is located approximately under each LM12458 DAS-chip.

See figure 1-12 for detailed locations of these jumpers.

Fig. 1-12 Location of DAS reference jumpers B1,B6,B3,B5



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CHAPTER 2 - BOARD INSTALLATION

==============================================================

The DM5414/DM6414 is easy to install in your cpuModule™ of other PC/104 based system. This chapter tells you step-by-step how to connect your module into your stack.

After you have made all of your connections, you can turn on your computer and run the diagnostic and test software to verify that your module is working.


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Board installation

Keep your board in its antistatic bag until you are ready to install it to your system!

When removing it from the bag, hold the board at the edges and do not touch the components or connectors. Please handle the board in an antistatic environment and use a grounded workbench for testing and handling of your hardware.

Before installing the board in your computer, check the jumper settings. Chapter 1 reviews the factory settings and how to change them. If you need to change any settings, refer to the appropriate instructions in Chapter 1. Note that incompatible jumper settings can result in unpredictable board operation and erratic response.

General installation guidelines:

1. Turn OFF the power to your computer

2. Touch the grounded metal housing of your computer to discharge any

antistatic buildup and then remove the board from its antistatic bag.

3. Select the appropriate standoffs for your application to secure the module

when you install it in your system.

4. Holding the module by it's edges, orient it so that the PC/104 bus connector

pin 1 lines up with pin 1 of the expansion connector onto which you are installing

the module.

5. After carefully positioning the module so that the card edge connector is resting

on the expansion connector, gently and evenly press down on the module until it

is secured on the connector.

Note: Do NOT force the module onto the connector. If the module does not slide into place remove it and try again. Wiggling the module or exerting too much pressure on the module can result in damage to the DM5414 or other boards in the stack.

6. After the module is installed, connect the cable or cables to the analog expansion

connectors J3 and J4. When making this connection , note that pin one is marked

with a square on the top side of the board. For twisted pair cables, pin 1 is the dark

brown wire; for standard 50 flat cables pin one is often marked in red.

7. Make sure all connections are secure.


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Fig. 2-1 DM5414 integrated with a PC/104 dataModule™ stack

3U rack or enclosure installation with a EUROCARD CPU with one DM5414.

The PC/104 system can easily be inserted into a 19" rack installation using the CPU as a "form factor adapter". Assemble your PC/104 dataModules™ on a RTD single board

EUROCARD computer and install the system in a 19" enclosure. Multiple DM5414 boards can easily be connected to this system. See figure 2-2 for installation ideas.

Fig. 2-2 19" Eurocard rack installation with an integrated PC/104 dataModule™

and EUROCARD cpuModule™ computer system


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External I/O connections

Primary 50 Pin Analog Digital Expansion Connector

Figure 2-3 shows the DM5414 's J3 primary I/O connector pinout. Figure 2-4 shows the DM5414 's J4 secondary I/O connector pinout. Refer to these diagrams when you are making I/O connections. Note that +12V at pins #47 and -12V at pins #49 are only available if your system bus supplies these voltages. These voltages are not generated by the DM5414.

PA6

PA5

PA4

PA3

PA2

PA1

PA0

TRIGGER IN

EXT GATE 1

SYNC IN/OUT

EXT CLOCK

+12V (VCC)

-12V (VSS)

AIN1

AIN2

AIN3

AIN4

AIN5

AIN6

AIN7

AIN8

AOUT1

AOUT2

AGND

PA7

*1

*3

*5

*7

*9

*2

*4

*6

AIN9

AIN10

AIN11

*8 AIN12

*10 AIN13

*11 *12 AIN14

*13 *14 AIN15

*15 *16 AIN16

*17 *18 AGND

*19 *20 AGND

*21 *22 AGND

*23 *24 PC7

*25 *26 PC6

*27 *28 PC5

*29 *30 PC4

*31 *32 PC3

*33 *34 PC2

*35 *36 PC1

*37 *38 PC0

*39 *40 DGND

*41 *42 T/C OUT 1

*43 *44 T/C OUT 2

*45 *46 EXT GATE 2

*47 *48 +5V

*49 *50 DGND

Fig. 2-3 Primary expansion connector pinout J3

NOTE:

Digital I/O ports PC[0..7] are port programmable inputs or outputs and are derived from the advanced Digital Interface Chip. Port PA[0..7] is bit programmable and has Advanced Masking Modes. Please refer to the more detailed discussion on the functionality of the digital I/O in Chapter 3.


Secondary 50 Pin Analog Digital Expansion Connector

IN6

IN5

IN4

IN3

IN2

IN1

IN0

EXT_SYNC IN

EXT GATE 1

SYNC IN/OUT

EXT CLOCK

+12V (VCC)

-12V (VSS)

AIN17

AIN18

AIN19

AIN20

AIN21

AIN22

AIN23

AIN24

AOUT3

AOUT4

AGND

IN7

*1

*3

*5

*7

*9

*49

*2

*4

*6

*8

*50

AIN25

AIN26

AIN27

AIN28

*10 AIN29

*11 *12 AIN30

*13 *14 AIN31

*15 *16 AIN32

*17 *18 AGND

*19 *20 AGND

*21 *22 AGND

*23 *24 OUT7

*25 *26 OUT6

*27 *28 OUT5

*29 *30 OUT4

*31 *32 OUT3

*33 *34 OUT2

*35 *36 OUT1

*37 *38 OUT0

*39 *40 DGND

*41 *42 T/C OUT 1

*43 *44 T/C OUT 2

*45 *46 EXT GATE 2

*47 *48 +5V

DGND

Fig. 2-4 Secondary expansion connector pinout J4

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Page 31

Connecting the analog inputs

The analog inputs on this module can be set for single ended or differential operation. All channels can be configured to work in a differential mode, but only those channels that are

grouped to one DAS chip can be differential i.e.. channels 1-8, 9-16, 16-24 and channels

25-32.

Single ended When the input channels are configured for single ended operation, connect the high side of the signal to one of the analog input channels, AIN1 - AIN32.

Figure 2-5 shows how these connections are made.

Differential When operating in this mode, your signal source may or may not have a separate ground reference. First connect the high side of the analog signal to the selected analog input channel of the channel group you are using (see above), and connect the low side of the signal to another analog input channel of the channel group you are using.

Then, for signal sources with a separate ground reference, connect the ground from the signal source to one of the analog ground pins on the expansion connector you are using.

Figure 2-6 shows how these connections are made.


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Fig. 2-7 Differential Input Connection


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Connecting the Analog Outputs

For each of the four analog outputs, connect the high side of the device receiving the output to the AOUT channel (J3-17, J3-19, J4-17, J4-19) and connect the low side of the device to an ANALOG GROUND (J3-18, J3-20, J4-18, J4-20).

Connecting the Timer/Counters and Digital I/O

For all these connections, the high side of the signals are connected to the appropriate signal pin on either the primary I/O connector J3 or the Secondary I/O connector J4. The low side of the signal shall be connected to any digital ground (GND).


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CHAPTER 3 - HARDWARE DESCRIPTION

==============================================================

This Chapter describes the features of the DM5414 hardware. The major circuits are the A/D-chips, the D/A converters, 8254-timer/counter, the digital I/O and the Advanced

Bit Programmable Digital I/O.


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The DM5414 has five major circuits, the four DAS-chips, the D/A-converter circuits, the 8254 timer/counter, the 8+8 general purpose digital I/O an the Advanced Bit Programmable

Digital I/O. This chapter describes the hardware which makes up the major circuits. Figure

3-1 shows a general block diagram of the DM5414.

Fig. 3-1 DM5414 Block Diagram

A/D Conversion Circuitry

The DM5414 can interface to 32 single ended or 16 differential input channels with a 0-2,5V or 0-5,0V input range. The conversion resolution and conversion rate are fully software configurable. The DM5414 is designed using the highly integrated LM12458 low power DAS-chip.

The A/D-chips are very flexible to program. The programming of the chips as well as the hardware description of the A/D-chips is published as a datasheet reprint of the

LM12458 chips. Programming these chips is discussed in detail in Chapter 4, Module Operation

and Programming.


Reprint of LM12458 DAS-Chip datasheet

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D/A Conversion Circuitry

Four 12-bit analog outputs are included on the DM5414. These four channels are grouped as follows: Channels 1 and 2 are located in the primary connector, Channels 3 and 4 are located in the secondary connector. Each of the channel pairs can have independent range settings. Each of the four channels can be set for bipolar or unipolar operation in the selected range. The 10 volt ranges have a resolution of 2,44 millivolts and the 5 volt range has a resolution of 1,22 millivolts.

Timer/Counters

An 8254 programmable interval timer provides three 16-bit, 8-Mhz timer / counters to support a wide range of timing and counting functions. Two of the timer/counters TC0 and TC1, are cascaded so that they can be used for the pacer clock. The pacer clock is described in

Chapter 4. Note, that each DAS-chip can use it's internal counter as a pacer clock freeing counter/timers TC0 and TC1 for user applications. Timer TC2 is always free for the user. The timers have different options for clock sources as well as gate signals. Figure 3-2 shows the timer counter circuitry of the DM5414.

Fig. 3-2 8254 Timer/Counter Circuit Block Diagram


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Each Timer/Counter has two inputs, CLK in and GATE in, and one output, timer/counter

OUT. They can be programmed as binary or BCD down counters by writing the appropriate data to the command word, as described in Chapter 4. The command word also lets you set up the different modes of operation. The six programmable modes are:

Mode 0

Mode 1

Mode 2

Mode 3

Mode 4

Mode 5

Event Counter (Interrupt on Terminal Count)

Hardware-Retriggerable one-shot

Rate Generator

Square Wave Mode

Software-Triggered Strobe

Hardware Triggered Strobe (Retriggerable)

Digital I/O, Advanced Bit Programmable Digital I/O

Two separate digital I/O ports are available on the DM5414. The primary digital

I/O port consists of an 8-bit port programmable port and an 8-bit bit programmable port.

Each bit can be programmed independently to be input or output in this port. All the bit programmable I/O lines are pulled down with a 10kohm resistor. The primary digital I/O port is located in the primary Analog Digital I/O expansion connector J3.

The secondary general purpose digital I/O port has 8 latched TTL/CMOS compatible outputs and 8 TTL/CMOS compatible inputs with 10kohm pulldown resistors. The direction and configuration of the general purpose digital I/O-port is fixed to 8 outputs and 8 inputs. The secondary digital I/O port is located in the secondary Analog Digital I/O expansion connector J4.

The internal Advanced Modes of the bit Programmable digital I/O port are discussed in detail in Chapter 4.


CHAPTER 4 - BOARD OPERATION AND PROGRAMMING

==============================================================

This chapter explains the I/O map of the DM5414 in detail and shows how to program the onboard peripherals such as the LM12458 DAS-chips, the 8254 Timer and the Digital I/O.

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Defining the I/O Map

The I/O map of the DM5414 is shown in Tables 4-1 and 4-2. As shown the board occupies 48 consecutive I/O addresses.

To conserve the use of I/O space, the structure of the I/O map is such that some of the registers control what peripherals are accessed in other addresses. The control registers at addresses BA+20 and BA+21 select the active DAS- or D/A-chips and select either the

8254 timer of the Advanced Bit Programmable Digital I/O-chip. These functions can easily be understood by reviewing the following pages.

The Base Address (designated as BA) can be selected by the two base address jumpers as described in Chapter 1, Module Settings. These jumpers can be changed without removing the module from the PC/104 stack. The following sections describe the register contents of each address used in the I/O map.

Table 4-2 shows the I/O address locations for each DAS chip. The active DAS chip is selected with the DAS selection register located in address BA+20.


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Table 4-1 DM5414 I/O Map Other Peripherals

Address

BA+20

BA+21

Description #1

Write only

Read/Write

Description #2

DAS-chip selection register

Rd->Load DACs, Wr-> DAC-chip select , Overlay bit

Reserved

Software trigger

BA+22

BA+23

Overlay = 0

Reserved

Write

BA+24

BA+25

BA+26

BA+27

Read/Write

Read/Write

Read/Write

Write only

Overlay = 1

BA+24 Read/Write

BA+25 Read/Write

BA+26

BA+27

Read/Write

Write only

8254 Timer/Counter 0



8254 Control byte

Port 0 Data register

Port 1 Data register

Port 0 Control Byte

Digital I/O-chip Control byte

BA+28

BA+29

BA+2A

BA+2B

Write only

Write only

Write only

Write only

DAC #1 Register

DAC #1 Register

DAC #1 Register

DAC #1 Register

BA+2C

BA+2D

Read only

Read only

Board setup register #1

Board setup register #2

BA+2E

BA+2F

Read/Write

Reserved

Digital I/O (Connector J4)

Reserved

BA = Base Address , Overlay bit is bit 2 in address BA+21


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Table 4-1 DM5414 I/O Map DAS-chips

Address Description #1 Description #2

BA+0

BA+1 ...

RAM Pointer 00 (Program)

-"-

Sequencer Instruction #0

Parameter field for Instruction #0

BA+E

BA+F

-"-

-"-

Sequencer Instruction #15

Parameter field for Instruction #15

BA+0

BA+1 ...

BA+E

BA+F

BA+0

BA+1 ...

BA+E

BA+F

RAM Pointer 01 (Cmp. low limit) Comparison low limit #0

-"-

-"-

-"-

Polarity of Cmp. intr/sign of low limit #0

Comparison low limit#15

Polarity of Cmp. intr/sign of low limit #15

RAM Pointer 10 (Cmp. high limit) Comparison high limit #0

-" Polarity of Cmp. intr/sign of high limit #0

-"-

-"-

Comparison high limit #15

Polarity of Cmp. intr/sign of high limit #15

BA+10

BA+11

BA+12

BA+13

BA+14

BA+15

BA+16

BA+17

BA+18

BA+19

BA+1A

Read/Write

Read/Write

Read/Write

Read/Write

Read/Write

Read/Write

Read/Write

Read/Write

Read/Write

Read/Write

Read/Write

DAS Configuration Register #1

DAS Configuration Register #2

DAS Interrupt Enable Register #1

DAS Interrupt Enable Register #2

DAS Interrupt Status Register #1

DAS Interrupt Status Register #2

DAS Acquisition Timer Register #1

DAS Acquisition Timer Register #2

DAS Conversion FIFO low byte

DAS Conversion FIFO high byte

DAS low Limit Status Register

BA+1B Read/Write DAS high Limit Status Register

Identical I/O addressing for each DAS-chip, Chip selected in cnf. register BA+20


DM5414 I/O Map Other Peripherals

BA+20

DAS-chip selection register Write

D3 D2 D1 D0 Register bits

DAS-selected "1"

DAS3 DAS2

DAS1 DAS0

BA+21

DAC control register Write

D2 D1 D0 Register bits

DAC Select "1"

Overlay "1" -> Dig. I/O

DAC1 DAC0 Overlay "0" -> Timer

OVERLAY

BA+21

DAC control register Read

Performing a read to this address will load the D/A converters with the output data written to the D/A-output registers.

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Overlay Bit = 0

BA+24 8254 Timer/Counter 0 Write/Read

A read to this address shows the current contents of the timer T0. A write to this address reloads a new value to the timer. Counting begins as soon as the timer has bee loaded.

This timer is cascaded with timer T1 to form the 32-bit pacer clock on the DM5414.



This timer is cascaded with timer T0 to form the 32-bit pacer clock on the DM5414.



This timer is cascaded with timer T0 and T1 or used independently. The output of this timer may be connected to the external trigger input of the DM5414.

BA+27 8254 Control word Write only

D7 D6 D5 D4 D3 D2 D1 D0

COUNT SEL.

00-counter0

01-counter1

10-counter2

11-readback

READ/LOAD

00-Latching

01-RD/LD LSB only

10-RD/LD MSB only

11-RD/LD LSB+MSB

BCD/BIN

0-BINARY

1-BCD

COUNTER MODE

000-Mode0, event count

001-Mode1, programmable 1-shot

010-Mode2, rate generator

011-Mode3, sq. wave rate generator

100-Mode4, software triggered strobe

101-Mode5, hw. triggered strobe


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Overlay Bit = 1

BA+24 Digital I/O Port 0 Write/Read

D7 D6 D5 D4 D3 D2 D1 D0

P0.7

P0.6

P0.5

P0.4

P0.3

P0.2

P0.1

P0.0

This port transfers the 8-bit port 0 bit programmable digital I/O data between the board and external devices. The bits are individually programmable as inputs or outputs by writing to the Direction Control Register at BA+26. For all bits set as inputs, a read reads the input values and a write operation is ignored. For all the bits set as outputs, a read will return the last value written to the outputs and a write sends the value out.

Note: After a board reset all lines are set to inputs and their corresponding output registers are cleared!

BA+25 Digital I/O Port 1 Write/Read

D7 D6 D5 D4 D3 D2 D1 D0

I/O.7

I/O.6

I/O.5

I/O.4

I/O.3

I/O.2

I/O.1

I/O.0

This port transfers the 8-bit port 1 bit programmable digital I/O data between the board and external devices. The bits are individually programmable as inputs or outputs by writing to the Direction Control Register at BA+26. For all bits set as inputs, a read reads the input values and a write operation is ignored. For all the bits set as outputs, a read will return the last value written to the outputs and a write sends the value out.

Note: After a board reset all lines are set to be inputs and their corresponding output registers are cleared!


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BA+26 Port 0 Direction/Mask/Compare Write/Read

D7 D6 D5 D4 D3 D2 D1 D0

Register data "Don't care"

BA+27

BITS 0-1

00

Performing a write to this address with BA+27 register bits 0,1 at 00 will clear the digital chip from software. Performing a read will clear the interrupt status flag.

Direction Register

D7 D6 D5 D4 D3 D2 D1 D0

P0.7

P0.6

P0.5

P0.4

0 -> INPUT , 1 -> OUTPUT

P0.3

P0.2

P0.1

P0.0

Mask Register

BA+27

BITS 0-1

01

D7 D6 D5 D4 D3 D2 D1 D0

P0.7

P0.6

P0.5

P0.4

0 -> INPUT , 1 -> OUTPUT

P0.3

P0.2

P0.1

P0.0

BA+27

BITS 0-1

10

In the Advanced Interrupt modes, this register is used to mask out specific bits when monitoring the bit pattern present at port 0 for interrupt generation. In normal operation where the Advanced Interrupt feature is not being used, any bit which is masked by writing "1" to that bit will not change state regardless of the data written to port 0. For example, if you set the state of the bit o low and then mask this bit, the state will remain low regardless of what you output at port 0. (An output of 1 will not change the state of the output until the bit is unmasked.)


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Compare Register

BA+27 BITS 0-1 = 10

This register is used for the Advanced Digital Interrupt modes. In the match mode where an interrupt is generated when the port 0 bits match a preloaded value, this register is used to load the bit pattern to be matched at port 0. Bits can be selectively masked so that they are ignored when making the match. Note: Make sure that bit 3 in BA+27 is set to 1, selecting match mode, BEFORE writing to the Compare Register value at this address.

In the event mode where an interrupt is generated when any port 0 bit changes its current state, the value which caused the interrupt is latched at this register and can be read from it. Bits can also be selectively masked using the Mask Register so a change of state is

ignored on these lines in the event mode.

Read Digital IRQ Status/Program Digital Mode

BA+27 Write/Read

A read shows you whether a digital interrupt has occurred (bit 6), whether a strobe has occurred (bit 7), and lets you review the current state of bits 0-5

Read

D7 D6 D5 D4 D3 D2 D1 D0

Strobe status

0 = no, 1= yes

Digital IRQ status

0 = no interrupt

1 = dig. interrupt

BA+27 port 0 reg. select

Port 1 direction

Digital IRQ mode

Digital IRQ enable

Digital sample clock select

D7 D6 D5 D4 D3 D2 D1 D0

Write

Reserved bits

Digital Sample CLK

0 = 8 MHz system clock

1 = Programmable clock

Digital IRQ enable

0 = disabled

1 = enabled

BA+27 port 0 reg. select

00=clear mode

Port 1 dir.

0 = input

1 = output

01=dir. register

10=mask reg.

11=comp reg.

Digital IRQ mode

0 = event mode

1 = match mode


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Bits 0 and 1 Select the clear mode initiated by the read or write operation at BA+26 or the port 0 control register you talk to at BA+27 (Direction, Mask, or Compare Register)

Bit 2

Bit 3

Sets the direction of Port 1 digital lines

Selects the digital interrupt mode: event (any Port 0 bits change state) or match (port 0 match the preprogrammed value in the Compare Register at address BA+27)

Bit 4

Bit 5

Bit 6

Bit 7

Disables/Enable digital interrupts

Sets the clock rate at which the digital lines are sampled when in the digital interrupt mode. Available clock source is the 4 MHz system clock. When a digital input line changes state, it must stay stable for two edges of the clock pulse before it's recognized and before an interrupt can be generated.

This feature eliminated noise glitches that can cause a false state change on an interrupt line and cause an unwanted interrupt.

Read only (digital IRQ status)

Read only (digital strobe status)

BA+28

BA+29

DAC channel 1 in selected chip, register low byte

DAC channel 1 in selected chip, register high byte

BIT 1

0

0

1

1

BA+2A

BA+2B

DAC channel 2 in selected chip, register low byte

DAC channel 2 in selected chip, register high byte

Writing to the register pairs will store the data into the currently enabled D/A channels selected in the address BA+21 bits 0 and 1. These bits enable the D/A converter chips as follows

BA+21 DAC chip enable bit definitions

BIT 0

0

1

0

1

D/A channels addressed

D/A converters are all disabled

channels 1 & 2 in DAC chip 1

channels 3 & 4 in DAC chip 2

Channels 1,2,3 and 4 in both chips

Example: Write data to DAC channel 3.

Step 1. Enable DAC chip 2 by writing bit 1 to 1 and bit 0 to 0

Step 2.

Step 3.

Write low byte and high byte to BA + 29 and BA + 30

Load DAC storage registers to analog outputs by reading from BA+21.

NOTE: Writing to storage registers will not update the outputs!


After the DAC storage registers are loaded you must perform a load to transfer the data to the outputs. This is performed by reading from BA+21. The read cycle will trigger the contents of the storage registers to the analog outputs.

BA+2C Board setup register #1 Read only

This register returns the status of the internal control bits of the register in

BA+20 (DAS chip selection ) the DM5414.

D3 D2 D1 D0 Register bits

DAS-selected "0"

DAS3 DAS2

DAS1 DAS0

BA+2D Board setup register #2 Read only

This register returns the status of the internal control bits of the the DM5414; DAC selection bits and the overlay bit. Bit #3 is the interrupt

Status bit of the Advanced Digital I/O chip

D3 D2 D1 D0

Register bits

DAC-selected "0"

DAC1 DAC0

PPI_IRQ STAT

OVERLAY

BA+2E Digital I/O register Write/Read

The DM5414 features 16 general purpose digital I/O in two ports. One 8-bit output port and an 8-bit input port. These ports are available at the secondary

I/O connector J4. The pinouts are described in figure 2-4. The input port has

47K pulldown resistors connected to each input line.

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D7 D6 D5 D4 D3 D2 D1 D0

OUT7 OUT6 OUT5 OUT4 OUT3 OUT2 OUT1 OUT0

Write

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D7 D6 D5 D4 D3 D2 D1 D0

IN7 IN6 IN5 IN4 IN3 IN2 IN1 IN0

Read

BA+2F Board status register Read only

This register returns the board general status bits. This information may be used to read back the hardware interrupt output states of the DAS chips.

D7 D6 D5 D4 D3 D2 D1 D0

RESERVED BITS DAS3 DAS2 DAS1 DAS0


LM12458 DAS Chip programming datasheet reprinted

This section describes the internal programmable functions of each

DAS chip. Make sure you enable the correct chips for programming first by setting the DAS-enable bits in address BA+20!

Page 52


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Programming the DM5414

This section gives you some general information about programming the DM5414 board, and then walks you through the major programming functions of the DM5414. These descriptions will help you as you use the example programs and function libraries included with this board.

All of the program descriptions use decimal values unless otherwise specified.

The DM5414 is programmed by writing to and reading from the correct I/O-port addresses of the board. These I/O ports were described in the previous section of this chapter.

The following example shows how to perform a 8-bit read and write I/O port addresses using

"C"-syntax and assembly code:

Read: Write:

"C"-syntax

Assembly

var = inp(address);

mov dx,address

in ax,dx

outp(address,data);

mov dx,address

mov ax,data

out dx,ax

8-bit operations must be performed to the DM5414 board to ensure correct operation.

Clearing and setting bits in an I/O port

When you clear or set bits in an I/O port you must be careful not to alter the status of other bits. You can preserve the status of all the bits you do not wish to change by proper use of the bitwise AND- and OR-operators. Using and or operators, single or multiple bits can easily be set or cleared in one line operations.

1) To clear a single bit in a port, AND the current value of the port with the value "B", where B = 255 - 2 (exp) bit.

2) To set a single bit in a port, OR the current value of the port with the value "B", where B = 2 (exp) bit.

Bits are numbered from 0-7 for the low byte of a word and from 8-15 for the high byte of a word. Setting and clearing of multiple bits in a bye or word is more complex.

3)

4)

To clear multiple bits in a port, AND the current value of the port with the value "B", where B = 255 - (the sum of the values of the bits to be cleared). Note that the bits do not have to be consecutive.

To set multiple bits in a port, OR the current value of the port with the value "B", where B = (sum of the individual bits to be set).


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A/D conversions

The A/D converter chip data acquisition sequencers must first be programmed to before A/D conversions can be made. Conversions can not be directly started from the host program with a single command. A/D conversions are performed by the DAS chips based on the data acquisition seqencer program. Conversion data is stored into the DAS chip internal FIFO, where it can be retrieved by the host. Before the DAS chips can be programmed they must be enabled by writing 1 to the correct DAS-enable bits of the register located in address BA+20. After this you may program the internal data acquisition sequencers to make conversions in the way you choose. Please refer to the component datasheet for more specific details on the different options and modes of conversions.

Interrupts

- What is an interrupt ?

An interrupt is an event that causes the processor in your computer to temporarily halt its current process and execute another routine. Upon completion of the new routine, control is returned to the original routine at the point where its execution was interrupted.

Interrupts are a very flexible way of dealing with asynchronous events. Keyboard activity is a good example; your computer cannot predict when you might press a key and it would be a waste of processor time to do nothing while waiting for a keystroke to occur. Thus the interrupt scheme is used and the processor proceeds with other tasks. Then when a keystroke occurs, the keyboard 'interrupts' the processor , and the processor gets the keyboard data, placed it into memory, and then returns to what it was doing before the interrupt occurred. Other common devices that use interrupts are network cards, serial ports etc.

Your DM5414 can interrupt the main processor when a DAS-chip generates an interrupt or by the timer counter "Pacer clock". By using interrupts you can write powerful code to interface DM5414 board.

-Interrupt request lines

To allow different peripheral devices to generate interrupts on the same computer, the PC

AT bus has interrupt request channels (IRQ's). A rising edge transition on one of these lines will be latched into the interrupt controller. The interrupt controller checks to see if the interrupts are to be acknowledged from that IRQ and, if another interrupt is being processed, it decides if the new request should supersede the one in progress or if it has to wait until the one in progress is done. The priority level of the interrupt is determined by the number of the IRQ; IRQ0 has the highest priority IRQ15 the lowest. Many of the IRQ's are used by the standard system resources.

IRQ0 is dedicated for the internal timer, IRQ1 is dedicated to the keyboard input, IRQ3 for serial port COM2 and IRQ4 for serial port COM1. Often interrupts 2,5 and 7 are free for the user.


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- 8259 Programmable Interrupt Controller

The chip responsible for handling interrupt requests in a PC is the 8259 Interrupt

Controller. To use interrupts you will need to know how to read and set the 8259's internal interrupt mask register (IMR) and how to send the end-of-interrupt (EOI) command to acknowledge the 8259 interrupt controller.

-Interrupt Mask Register (IMR)

Each bit in the interrupt mask register (IMR) contains the mask status of the interrupt line.

If a bit is set (equal to 1), then the corresponding IRQ is masked, and it will not generate an interrupt. If a bit is cleared (equal to 0), then the corresponding IRQ is not masked, and it can generate an interrupt. The interrupt mask register is programmed through port 21h.

-End-of-Interrupt (EOI) Command

After an interrupt service routine is complete, the 8259 Interrupt Controller must be acknowledged by writing the value 20h to port 20h.

-What exactly happens when an interrupt occurs?

Understanding the sequence of events when an interrupt is triggered is necessary to correctly write interrupt handlers. When an interrupt request line is driven high by a peripheral device (such as the DM5414), the interrupt controller checks to see if interrupts are enabled for that IRQ, and then checks to see if other interrupts are active or requested and determines which interrupt has priority. The interrupt controller then interrupts the processor. The current code segment (CS), instruction pointer (IP), and flags are pushed onto the system stack., and a new set if CS and IP are loaded from the lowest 1024 bytes of memory.

This table is referred to as the interrupt vector table and each entry to this table is called an interrupt vector. Once the new CS and IP are loaded from the interrupt vector table , the processor starts to execute code from the new Code Segment (CS) and from the new

Instruction Pointer (IP). When the interrupt routine is completed the old CS and IP are popped from the system stack and the program execution continues from the point it was interrupted.

-Using Interrupt in your Program

Adding interrupt support to your program is not as difficult as it may seem especially when programming under DOS. The following discussion will cover programming under DOS.

Note, that even the smallest mistake in your interrupt program may cause the computer to hang up and will only restart after a reboot. This can be frustrating and time-consuming.

-Writing an Interrupt Service Routine (ISR)

The first step in adding interrupts to your software is to write an interrupt service routine


Page 56

(ISR). This is the routine that will be executed automatically each time an interrupt request occurs for the specified IRQ. An ISR is different from other subroutines or procedures. First, on entrance the processor registers must be pushed onto the stack before anything else! Second, just before exiting the routine , you must clear the interrupts on the DM5414 DAS chips, and write the EOI command to the interrupt controller. Finally, when exiting the interrupt routine the processor registers must be popped from the system stack and you must execute the IRET assembly instruction. This instruction pops the CS, IP and processor flags from the system stack.

These were pushed onto the stack when entering the ISR.

Most compilers allow you to identify a function as an interrupt type and will automatically add these instructions to your ISR with one exception: most compilers do not automatically add the EOI command to the function, you must do it yourself. Other than this and a few exceptions discussed below, you can write your ISR as any code routine. It can call other functions and procedures in your program and it can access global data. If you are writing your first ISR, we recommend you stick to the basics; just something that enables you to verify you have entered the

ISR and executed it successfully. For example: set a flag in your ISR and in your main program check for the flag.

Note: If you choose to write your ISR in in-line Assembly , you must push and pop registers correctly, and exit the routine with the IRET instruction instead of the RET instruction.

There are a few precautions you must consider when writing ISR's. The most important is, do not use any DOS functions or functions that call DOS functions from an interrupt

routine. DOS is not reentrant; that is, a DOS function cannot call itself. In typical programming, this will not happen because of the way DOS is written. But what about using interrupts? Then, you could have the situation such as this in your program. If DOS function X is being executed when an interrupt occurs and the interrupt routine makes a call to the DOS function X, then function X is essentially being called while active. Such cases will cause the computer to crash.

DOS does not support such operation. A general rule is , that do not call any functions that use the screen, read keyboard input and any file I/O routines should not be used in ISR's.

The same problem of reentrancy exists for many floating point emulators as well, meaning you should avoid floating point mathematical operations in your ISR.

Note, that the problem of reentrancy exists, no matter what programming language you use. Even, if you are writing your ISR in Assembly language, DOS and many floating point emulators are not reentrant. Of course, there are ways to avoid this problem, such as those which involve checking if any DOS functions are currently active when your ISR is called, but such solutions are beyond the scope of this manual.

The second major concern when writing ISR's is to make them as short as possible in term of execution time. Spending long times in interrupt service routines may mean that other important interrupts are not serviced. Also, if you spend too long in your ISR, it may be called again before you have exited. This will lead to your computer hanging up and will require you to restart your computer.


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Your ISR should have the following structure:

Push any processor registers used in your ISR. Most C compiler do this automatically

Put the body of your routine here

Read interrupt status register of the DAS-chips on your DM5414 board

Issue the EOI command to the 8259 by writing 20h to address 20h

Pop all registers. Most C compilers do this automatically

The following C example shows what the shell of your ISR should be like:

/*-------------------------------------------------------------------------------

| Function: new_IRQ_handler

| Inputs: Nothing

| Returns: Nothing - Sets the interrupt flag for the EVENT.

|-------------------------------------------------------------------------------*/ void interrupt far new_IRQ_handler(void)

{

IRQ_flag = 1; // Indicate to main process interrupt has occurred

{

// Your program code should be here

}

// Read interrupt status registers that

// clears interrupts in DAS chip NOTE: all active chips

// must be read since all DAS interrupts are connected together outp(0x20, 0x20); /* Acknowledge the interrupt controller. */

}

-Saving the Startup Interrupt Mask Register (IMR) and interrupt vector

The next step after writing the ISR is to save the startup state of the interrupt mask register (IMR) and the original interrupt vector you are using. The IMR is located in address 21h.

The interrupt vector you will be using is located in the interrupt vector table which is an array of

4-byte pointers (addresses) and it is locate din the first 1024 bytes of the memory (Segment 0 offset 0). You can read this value directly, but it is a better practice to use DOS function 35h

(get interrupt vector) to do this. Most C compilers have a special function available for doing this.

The vectors for the hardware interrupts on the XT - bus are vectors 8-15., where IRQ0 uses vector 8 and IRQ7 uses vector 15. Thus if your DM5414 is using IRQ5 it corresponds to vector number 13.


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Before you install your ISR, temporarily mask out the IRQ you will be using. This prevents the IRQ from requesting an interrupt while you are installing and initializing your ISR.

To mask the IRQ, read the current IMR at I/O port 21h, and set the bit that corresponds to tout IRQ. The IMR is arranged so that bit 0 is for IRQ0 and bit 7 is for IRQ7. See the paragraph entitled Interrupt Mask Register (IMR) earlier in this discussion for help in determining your

IRQ's bit. After setting the bit, write the new value to I/O port 21h.

with the startup IMR saved and the interrupts temporarily disabled, you can assign the interrupt vector to point to your ISR. Again you can overwrite the appropriate entry in the vector table with a direct memory write, but this is not recommended. Instead use the DOS function 25h

(Set Interrupt Vector) or, if your compiler provides it, the library routine for setting up interrupt vectors. Remember , that interrupt vector 8 corresponds to IRQ0 , vector 9 for IRQ1 etc.

If you need to program the source of your interrupts, do that next. For example, if you are using transmitted or received messages as an interrupt source , program it to do that.

Finally, clear the mask bit for your IRQ in the IMR. This will enable your IRQ.

-Common Interrupt mistakes

Remember, hardware interrupts are from 8-15, XT IRQ's are numbered 0-7

Forgetting to clear the IRQ mask bit in the IMR

Forgetting to send the EOI command after ISR code. Disables further interrupts.

Example on Interrupt vector table setup in C-code:

void far _interrupt new_IRQ1_handler(void );

#define IRQ1_VECTOR 3

/* ISR function prototype */

/* Name for IRQ */ void (interrupt far *old_IRQ1_dispatcher)

(es,ds,di,si,bp,sp,bx,dx,cx,ax,ip,cs,flags); /* Variable to store old IRQ_Vector */ void far _interrupt new_IRQ1_handler(void );

/*----------------------------------------------------------------------

| Function: init_irq_handlers

| Inputs: Nothing

|

| Purpose: Set the pointers in the interrupt table to point to our funtions ie. setup for ISR's.

|----------------------------------------------------------------------*/ void init_irq_handlers(void)

{

_disable(); old_IRQ1_handler = _dos_getvect(IRQ1_VECTOR + 8);

_dos_setvect(IRQ1_VECTOR + 8, new_IRQ1_handler);

Gi_old_mask = inp(0x21); outp(0x21,Gi_old_mask & ~(1 << IRQ1_VECTOR));

_enable();

}


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D/A conversions

Two individual D/A converter chips with two channels each can be programmed to convert 12-bit digital words to an analog output voltage. To write to the D/A channels you must first enable the D/A converter chip by setting the correct D/A selection bit in the D/A setup register located in address BA+21.

After the D/A chip is selected you may write your 12-bit data to the appropriate D/A data storage register. Note that this register data will not appear at the outputs before you issue a "load" instruction. This is performed by reading from address BA+21. After this the data in the storage registers is transferred to the analog outputs. This feature enables simultaneous updating of all the analog output channels.

Timer/Counters

An 8254 programmable interval timer provides three 16-bit, 8 MHz timer/counters for timing and counting purposes such as frequency measurement, event counting, and interrupts.

Two of the timers can be cascaded to generate the "pacer clock". The remaining timer/counter is available for other use. Figure 4-1 shows the timer counter circuitry.

Each timer/counter has two inputs, CLK in and GATE in, and one output, timer/counter OUT. They can be programmed as either binary or BCD down counters by writing the appropriate data to the 8254 Control word as described in the I/O map description earlier in this chapter.

One of the two clock sources, the onboard 8 MHz crystal oscillator or the external clock (J3 pin 45) can be selected as the clock input to TC0 or TC1. The diagram shows how these clock sources are connected to the timer/counters.

Two gate sources are available at the I/O connector (J3 pin 41 and J3 pin 46). When the gate is disconnected an onboard pull-up resistor automatically pulls the gate high, enabling the timer/counters.

The output from timer/counter 1 is available at the T/C 1 OUT pin (J3 pin 42) and the timer/counter 2's output is available at T/C 2 OUT (J3 pin 44), where they can be used for interrupt generation, DAS triggers or for other counting purposes.

The timer/counters can be programmed to operate in one of six modes, depending on your application. The following section briefly describes each mode.


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Fig. 4-1 Block diagram of the timer counter unit of your DM5414

Mode 0 Event Counter

This mode is typically used for event counting. While the timer/counter counts down, the output is low, and when the count is complete, it goes high. The output stays high until a new mode 0 control word is written to the timer/counter.

Mode 1 Hardware -Retriggerable one-shot

The output is initially high and goes low on the clock pulse following a trigger to begin the one-shot pulse. The output remains low until the count reaches 0, and then goes high and remains high until the clock pulse after the next trigger.

Mode 2 Rate generator

This mode functions like a divide-by-N counter and is typically used to generate a real-time-clock interrupt. The output is initially high, and when the count decrements to 1, the output goes low for one clock pulse. The output then goes high again, the counter reloads the initial count, and the process is repeated. This sequence continues indefinitely.


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Mode 3 Square wave mode

Similar to mode 2 except for the duty cycle output, this mode is typically used for baud-rate generation. The output is initially high, and when the counter decrements to one half of its initial count the output goes low for the remainder of the count. The counter reloads and the output goes high again. This process repeats indefinitely.

Mode 4 Software triggered strobe

The output is initially high. When the initial count expires, the output goes low for one clock pulse and then goes high again. Counting is triggered by writing the initial count.

Mode 5 Hardware triggered strobe

The output is initially high. Counting is triggered by the rising edge of the gate signal.

When the initial count has expired, the output goes low for one clock pulse and goes high again.

Digital I/O

The Advanced Digital I/O chip digital I/O signals available in connector J3. are programmed according to the discussion earlier on in this chapter. The standard 16 bit general purpose digital I/O available in connector J4 is directly programmable using standard input and output instructions.


Example programs

This section will be completed later. See your DM5414 utility disk for the selection of example programs in C-code.

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APPENDIX A

=====================================================================

DM5414/DM6414 Specifications

Host Interface

I/O mapped , occupies 32 bytes

Jumper-selectable base address, 4 options

8-bit data bus, 16 bit PC/104 bus connector

Jumper selectable interrupts XT and AT

Analog Interfaces

32 analog inputs

(For full specification please consult component specific datasheet for the LM12458CIV A/D converter)

- 8-12 bit resolution, programmable

- 0 to 2,5V or 0- 5,0V input range

- Single ended or differential operation

- Interrupt support

4 analog outputs

- 12 bit resolution

- Simultaneously updated

- 4 output ranges , channel by channel configurable

0-5V, 0-10V, +-5V, +-10V

Digital I/O

Timers

Number of lines 16+16

- 16 register configured 8 inputs 8 outputs

- 8 bit programmable digital I/O lines

- 8 port programmable digital I/O lines with advanced modes

and Interrupt support

Number of timers 3 (8254 compatible)

- Clock sources include 8MHz oscillator or external source

- Counters cascadable

- External gating

- Interrupt support


Connectors

Analog /Digital I/O's

Host bus

Electrical

Operating temperature range

Supply voltage

Power consuption

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Header connectors 50-Pin

AT PC/104 bus

0 to 70C or -40 to +85 C

+5V only

1,5W


DM5414/DM6414 12-bit DAS

DM5414/DM6414

12-bit DAS-module

User's Manual

Real Time Devices Finland Oy

IMPORTANT

Table of Contents

Onboard Peripherals

Each of the DAS Chips

List of Illustrations

INTRODUCTION

Analog-to-Digital Conversion

Digital-to-Analog Conversions

8254 Timer/Counters

Digital I/O

Mechanical description

Connector description

What comes with your board

Board accessories

Using this manual

When you need help

CHAPTER 1 - BOARD SETTINGS

Factory-Configured Jumper settings

This page is left intentionally blank

This page is left intentionally blank

CHAPTER 2 - BOARD INSTALLATION

Board installation

External I/O connections

CHAPTER 3 - HARDWARE DESCRIPTION

A/D Conversion Circuitry

D/A Conversion Circuitry

Timer/Counters

Digital I/O, Advanced Bit Programmable Digital I/O

CHAPTER 4 - BOARD OPERATION AND PROGRAMMING

Defining the I/O Map

BA+20

BA+21

BA+21

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Overlay Bit = 0

BA+24 8254 Timer/Counter 0 Write/Read

BA+25 8254 Timer/Counter 1 Write/Read

BA+26 8254 Timer/Counter 2 Write/Read

BA+27 8254 Control word Write only

Overlay Bit = 1

BA+24 Digital I/O Port 0 Write/Read

BA+25 Digital I/O Port 1 Write/Read

BA+26 Port 0 Direction/Mask/Compare Write/Read

BA+27

BITS 0-1

00

BA+27

BITS 0-1

01

BA+27

BITS 0-1

10

BA+27 BITS 0-1 = 10

BA+27 Write/Read

Read

Write

BA+28

BA+29

DAC channel 1 in selected chip, register low byte

DAC channel 1 in selected chip, register high byte

BA+2A

BA+2B

DAC channel 2 in selected chip, register low byte

DAC channel 2 in selected chip, register high byte

BA+2C Board setup register #1 Read only

BA+2D Board setup register #2 Read only

BA+2E Digital I/O register Write/Read

Write

Read

BA+2F Board status register Read only

LM12458 DAS Chip programming datasheet reprinted

This section describes the internal programmable functions of each

DAS chip. Make sure you enable the correct chips for programming first by setting the DAS-enable bits in address BA+20!

Programming the DM5414

A/D conversions