STMicroelectronics STM8L microcontroller device Application note
STM8L is a microcontroller device. Its main features include an analog-to-digital converter (ADC), clock management, and reset control. The device uses the same toolchain as STM8S and STM8A, which makes development easier. This document provides a list of relevant documentation and online support resources.
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AN3029
Application note
Getting started with STM8L
Introduction
This application note complements the information in the STM8L datasheets by describing the minimum hardware and software environment required to build an application around an
STM8L 8-bit microcontroller device.
A brief description of the principal hardware components is given. The power supply, analog-to-digital converter (ADC), clock management, and reset control are described in some detail. In addition, some hardware recommendations are given. This application note also contains detailed reference design schematics with descriptions of the main components. The STM8L uses the same toolchain The STM8 development tools and software toolchain are common to STM8L, STM8S and STM8A and are presented in
, and
.
describes how to set up the STM8 development environment.
provides a list of relevant documentation and online support resources.
September 2009 Doc ID 16139 Rev 1 1/42
www.st.com
Contents
Contents
AN3029
Hardware requirements summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Power-on/power-down reset (POR/PDR) . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Analog-to-digital converter (ADC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Clock management overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
External source (LSE bypass) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
External crystal/ceramic resonator (LSE crystal) . . . . . . . . . . . . . . . . . . 15
Reset management overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Hardware reset implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
SS
, V
DD
) . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Unused I/Os and features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2/42 Doc ID 16139 Rev 1
AN3029
Contents
STM8 development tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Single wire interface module (SWIM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
SWIM connector pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Hardware connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
STice in emulation configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
In-circuit programming and debugging . . . . . . . . . . . . . . . . . . . . . . . . . 26
STM8 software toolchain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Integrated development environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Setting up the STM8 development environment . . . . . . . . . . . . . . . . . 29
Running the demonstration software . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Selecting the correct debug instrument . . . . . . . . . . . . . . . . . . . . . . . . . 34
Connecting the hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Starting the debug session . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Doc ID 16139 Rev 1 3/42
Contents
AN3029
Documentation and online support . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
4/42 Doc ID 16139 Rev 1
AN3029
List of tables
List of tables
Doc ID 16139 Rev 1 5/42
List of figures
List of figures
AN3029
DD
/V
SS
pair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Connecting the debug instrument to the STM8L101-EVAL evaluation board . . . . . . . . . . 35
Connecting the debug instrument to the STM8L15x-EVAL evaluation board . . . . . . . . . . 36
6/42 Doc ID 16139 Rev 1
AN3029
1
Hardware requirements summary
Hardware requirements summary
●
●
●
●
To build an application around an STM8L device, the application board should provide the following features:
Power supply (mandatory)
Clock management (optional)
Reset management (optional)
Debugging tool support: Single wire interface module (SWIM) connector (optional)
2.1 Power supply overview
The STM8L101 can be supplied through a 1.65 V to 3.6 V external source. The STM8L15x can be supplied through a 1.8 V to 3.6 V external source. However, after startup it can run on voltages down to 1.65 V.
An on-chip power management system provides the constant digital supply to the core logic, both in normal and low power modes. This garantees that the logic consumes a constant current over the voltage range. It is also capable of detecting voltage drops and generate reset to avoid heratic behaviour.
The STM8L device also provides:
●
One pair of pads, V
DD
/V
SS
(1.65 V or 1.8 V to 3.6 V)
The STM8L15x device also provides in the 48-pin package:
●
●
One pairs of pads dedicated for V
DDIO
/V
SSIO
, which are used to power only the I/O’s.
V
DDIO
and V
SSIO
must be at the same potential respectively as V
DD
and V
SS
.
One pair of pads, V
DDA
/V
SSA
, dedicated to analog functions. V
DDA
and V
SSA
must be at the same potential respectively as V
for more details.
DD
and V
SS
The STM8L152 device manages the supply voltage needed by the LCD in three different ways (see
1.
If the LCD feature is not used, connect the VLCD pin to V
DD
.
2. Apply to VLCD the voltage to be applied to the LCD.
3. Leave the STM8L152 to provide the correct voltage, via its programmable LCD booster, by connecting the VLCD pin to a 1µF capacitor.
Doc ID 16139 Rev 1 7/42
Power supply
Note:
AN3029
Figure 1.
Power supply
For noisy environment
Only if internal booster is used to power LCD
To power LCD specifi cally
2.5V<VLCD<3.6V
VDD
1uF
OR
For noisy environment
VSS
100 Ohm
3.6 V-1.8 V (1.65 V)
(see note 1)
100nF
VDD
VSS
1uF
VSS
1uF
100nF
100nF
100nF
Biggest package
VLCD
VDDA
VRef+
VDDIO
NRST
OSC_IN
OSC_OUT
VDD
VSSIO OSC32_IN
VSS/VSSA/VRefOSC32_OUT
VSS
OR
If LCD is unused
VDD
1.
The device keeps operating as long as the battery voltage is above 1.65 V and no reset is generated.
The capacitors must be connected as close as possible to the device supplies.
Placing a crystal/resonator on OSCIN/OSCOUT is optional. The resonator must be connected as close as possible to the OSCIN and OSCOUT pins. The loading capacitance ground must be connected as close as possible to V
SS
.
2.2 Main operating voltages
STM8L devices are processed in 0.13 µm technology. The STM8L core and I/O peripherals need different power supplies. In fact, STM8L devices have an internal regulator with a nominal target output of 1.8 V.
8/42 Doc ID 16139 Rev 1
AN3029 Power supply
The input supply to the main and low power regulators is monitored by a power-on/powerdown reset circuit. The monitoring voltage begins at 0.7 V.
During power-on, the POR/PDR keeps the device under reset until the supply voltages (V
DD and V
DDIO
) reach their specified working area. This internal reset is maintained during ~1ms in order to wait for supply stabilization.
At power-on, a defined reset should be maintained below 0.7 V. The upper threshold for a reset release is defined in the electrical characteristics section of the product datasheets.
A hysteresis is implemented (POR > PDR) to ensure clean detection of voltage rise and fall.
The POR/PDR also generates a reset when the supply voltage drops below the V
POR/PDR threshold (isolated and repetitive events).
For better power monitoring, the STM8L15x provides a programmable power voltage detection (PVD) and a brown out reset (BOR) for an earlier detection of voltage drop.
Recommendations
All pins need to be properly connected to the power supplies. These connections, including pads, tracks and vias should have the lowest possible impedance. This is typically achieved with thick track widths and preferably dedicated power supply planes in multi-layer printed circuit boards (PCBs).
In addition, each power supply pair should be decoupled with filtering ceramic capacitors (C) at 100 nF with one chemical C (1..2 µF) in parallel on the STM8L device. The ceramic capacitors should be placed as close as possible to the appropriate pins, or below the appropriate pins, on the opposite side of the PCB. Typical values are 10 nF to 100 nF, but
exact values depend on the application needs.
shows the typical layout of such a
V
DD
/V
SS
pair.
Figure 2.
Typical layout of V
DD
/V
SS
pair
Via to V
DD
Via to V
SS
Cap
.
V
DD
V
SS
STM8
Doc ID 16139 Rev 1 9/42
Analog-to-digital converter (ADC) AN3029
This section is unique for the STM8L15x.
For 48-pin packages, the ADC unit has an independent, analog supply voltage, isolated on input pin V
DDA
, which allows the ADC to accept a very clean voltage source. This analog voltage, V
DDA
, should be identical to the digital voltage supply on pin V
DD
. To filter some noise, a ferrite bead can be added between V
DD
and V
DDA
. This ferrite bead should be choosen according to the frequencies to be filtered.
The 48-pin package also provides a separate external analog reference voltage input for the
ADC unit on the V
REF+
pin. This gives better accuracy on low voltage input as follows:
●
V
REF+
(input, analog reference positive): The higher/positive reference voltage for the
ADC should be below or equal to V
DDA
. When V
DDA
is below 2.4 V, V
REF+
must be equal to V
DDA
. This input is bonded to V
DDA
in devices that have no external V
REF+
pin
(packages with 32 pins or less).
● V
REF-
(input, analog reference negative): The lower/negative reference voltage is internally bonded to V
SSA
.
10/42
STM8L15x devices have up to 28 analog input channels (including four fast channels), each multiplexed with an I/O, which are converted by the ADC one at a time.
The analog input interface of the ADC is shown in
ADC
, C
ADC
, and I
L
real values are given in the chip datasheet. The external input impedance (R
AIN
) max value, in order to achieve an error below 1/4 of LSB can be calculated with the formula:
Equation 1
R ain
<
( f
CPU
⁄ prescal
)
2
Nsc
×
C
TOTAL
× (
N+2
)
–
R
ADC
Where: f
CPU
is the CPU frequency.
Prescal is a programmable ADC clock prescaler with a value of 1 or 2. Usually f
CPU
/prescal is between 0.320 MHz and 16 MHz.
Nsc is the programmable number of sampling cycles. Usually the minimum number of cycles is four and the maximum is 384.
C
TOTAL
is the approximate sum of C parasitic
and C
ADC
.
N is the resolution which is programable between 6 and 12, but is usually 12.
R
ADC
is the sampling switch resistance which is usually around 1k
Ω..
.
Doc ID 16139 Rev 1
AN3029
Figure 3.
Analog input interface
Analog-to-digital converter (ADC)
STM8L15x
Please refer to the STM8L15x datasheet and reference manual for more details.
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Clock management AN3029
4.1
The STM8L101 has no external clock so no precautionary measures are needed. The following paragraph deals with STM8L15x chips only.
Clock management overview
STM8L15x devices offer a flexible way of selecting the core and peripheral clocks (ADC, memory, and digital peripherals). The devices have internal and external clock source inputs, both of which have a high speed and a low speed version. Any of those four clocks can be use for the CPU and most of the peripherals through a programable prescaler. An I/O can be programmed as output clock (CCO) to reflect one of the four clocks (with or without prescaling).
The signal which leaves the I/O represents an output clock (CCO) divided by a division factor.
STM8L devices have two kinds of internal clock: A high speed internal clock (HSI) running at
16 MHz and a low speed internal clock (LSI) running at 38 kHz.
After reset, the CPU starts with the internal RC (HSI clock signal) divided by 8, i.e. 2 MHz.
STM8L devices have two kinds of external clock: A high speed external clock (HSE) running at up to 16 MHz and a low speed external clock (LSE) running at 32.768 kHz.
Note:
STM8L15x devices can connect to an external crystal or an external oscillator.
When no external clock is used, OSCIN and OSCOUT can be used as general purpose
I/Os.
describes the external clock connections.
External clock
●
●
Frequency: 0 kHz … 16 MHz
Input hysteresis: 100 mV
Caution:
Without prescaler, a duty cycle of 45/55 % maximum must be respected at high speed
12/42 Doc ID 16139 Rev 1
AN3029
Crystal/ceramic resonator
●
●
●
●
●
●
●
Frequency range: 1 to 16 MHz
Stabilisation time: Programable from 1 to 4096 cycles
Oscillation mode: Preferred fundamental
Output duty cycle: Max 55/45%
I/O’s: Standard I/O pins multiplexed with OSC
IN
and OSC
OUT
Cload: 10 to 20 pF
Drive level maximum: at least 100 µW
Figure 4.
HSE clock sources
Hardware configuration
OSC
IN
STM8
OSC
OUT
(I/O available)
External source
Clock management
OSC
IN
STM8
OSC
OUT
R
EXT
(1)
Q1
C
L1
C
L2
Load capacitors
1.
The value of R
EXT
depends on the crystal characteristics. A 0
Ω resistor works well with most oscillators but, it is not optimal. A typical value is in the range 5 to 6 R
R
EXT
S
(resonator series resistance). To fine-tune the
value, refer to AN2867 (Oscillator design guide for ST microcontrollers).
The values of the load capacitors C
L1
and C
L2
are heavily dependent on the crystal type and frequency. Refer to the datasheet of the crystal manufacturer to select the capacitances. For best oscillation stability, C
L1
and C
L2
normally have the same value. Typical values are in the range from below 20 pF up to 40 pF (cload: 10 to 20 pF). The parasitic capacitance of the board layout also needs to be considered and typically adds a few pF to the component values.
A clock security system prevents any CPU fatal error from a HSE failure, as it safely switches to HSI.
Doc ID 16139 Rev 1 13/42
Clock management AN3029
Recommendations
In the PCB layout all connections should be as short as possible. Any additional signals, especially those that could interfere with the oscillator, should be locally separated from the
PCB area around the oscillation circuit using suitable shielding.
●
●
The low-speed external clock signal (LSE) can be generated from two possible clock sources:
LSE external crystal/ceramic resonator (see
LSE user external clock
)
Figure 5.
External clock
Microcontroller
OSC32_IN OSC32_OUT
(Hi-Z)
External source
ai15765
1.
OSC32_IN and OSC32_OUT pins can be used also as GPIO but, it is recommended not to use them as both RTC and GPIO pins in the same application.
Figure 6.
Crystal/ceramic resonators
Microcontroller
OSC32_IN OSC32_OUT
R
EXT
(3)
C
L1
C
L2 ai15764
1.
To avoid exceeding the maximum value of C
L1
and C
L2
(15 pF), it is strongly recommended to use a resonator with a load capacitance C
L
= 7 pF. To fine-tune the choice, refer to the g
AN2867 (Oscillator design guide for ST microcontrollers).
mcrit
calculation in
2.
OSC32_IN and OSC32_OUT pins can be used also as GPIO, but it is recommended not to use them as both RTC and GPIO pins in the same application.
3.
The value of R
EXT
depends on the crystal characteristics. A 0
Ω resistor works with most oscillators. A typical value is in the range 5 to 6 R
S
. To fine-tune the R
EXT value refer to AN2867 (Oscillator design guide for ST microcontrollers).
14/42 Doc ID 16139 Rev 1
AN3029
4.3.3
Clock management
External source (LSE bypass)
In this mode, an external clock source must be provided. It must have a frequency of
32.768 kHz. The external clock signal (square, sine or triangle) with a duty cycle of about
50% has to drive the OSC32_IN pin while the OSC32_OUT pin must be left high impedance
and
The LSE crystal is a 32.768 kHz low-speed external crystal or ceramic resonator. It has the advantage of providing a low-power, but highly accurate clock source to the real-time clock peripheral (RTC) for clock/calendar or other timing functions.
The resonator and the load capacitors have to be connected as close as possible to the oscillator pins in order to minimize output distortion and start-up stabilization time. The load capacitance values must be adjusted according to the selected oscillator.
Doc ID 16139 Rev 1 15/42
Reset control AN3029
5.1 Reset management overview
The reset pin is a 3.3 V bidirectional I/O. After startup it can be programmed by software to be used as a general purpose I/O.
Its output buffer driving capability is fixed to Iol
MIN
= 2 mA @ 0.45 V in the 1.8 V to 3.6 V range which includes a ~45 k pull-up. Output buffer is reduced to the n-channel MOSFET
(NMOS). The receiver includes a glitch filter, whereas the output buffer includes a 20 µs delay.
●
●
●
●
There are many reset sources, including:
●
●
External reset through the NRST pin
Power-on reset (POR) and brown-out reset (BOR): During power-on, the POR keeps the device under reset until the supply voltage (V
DD
and V
DDIO
) reach the voltage level at which level the BOR starts to function. STM8L101 has only a POR.
Independent watchdog reset (IWDG)
Window watchdog reset (WWDG), only for STM8L15x
Software reset: The application software can trigger reset
SWIM reset: An external device connected to the SWIM interface can request the
SWIM block to generate a microcontroller reset.
●
●
Illegal opcode reset: If a code to be executed does not correspond to any opcode or prebyte value, a reset is generated.
Electromagnetic susceptibility (EMS) reset: Generated if critical registers are corrupted or badly loaded.
shows a simplified functional I/O reset schematic.
Figure 7.
Reset management
STM8
VDD_IO
R
PU
Filter
NRST
Pulse generator
(min 20 µs
Delay
System reset
Illegal op code reset
IWDG/WWDG/software reset
SWIM reset
EMS reset
POR/BOR reset
16/42 Doc ID 16139 Rev 1
AN3029 Reset control
●
●
A valid pulse on the pin is guaranteed with a
≥ 20 ns pulse duration on the internal output buffer.
After a valid pulse is recognized, a pulse on the pin of at least 20 µs is guaranteed starting from the falling edge of A.
Figure 8.
Output characteristics
≥ 20 n
A
20 µs pulse stretch min
Reset requested
Pad
●
●
All pulses with a duration less than 50 ns are filtered
All train/burst spikes with a ratio of 1/10 must be filtered. This means that a negative spike of up to 50 ns is always filtered, when a 5 ns interval between spikes occurs (ratio
1/10).
All pulses with duration more than 300 ns are recognized as valid pulses ●
Figure 9.
Input characteristics
>5 ns >5 ns
300 ns
Pad
<50 ns <50 ns <50 ns
Negative train of glitch filtered Valid Reset requested
System reset
In most cases, the STM8L does not require an external reset circuit to power-up correctly.
The STM8L101 reset state is released 1 ms after the POR value (1.35 V to 1.65 V) is reached. At this time, V
DD
should be in the 1.65 V to 3.6 V range.
The STM8L15x reset state is released 1 ms after the BOR minimum value (~1.75 V) is reached.
Doc ID 16139 Rev 1 17/42
Recommendations
6 Recommendations
6.1
AN3029
Printed circuit board
For technical reasons, it is best to use a multi-layer PCB with a separate layer dedicated to the V
SS
and another layer to the V
DD
supply. This results in a good decoupling, as well as a good shielding effect. For many applications, economical requirements prohibit the use of this type of board. In this case, the most important feature is to ensure a good structure for the V
SS
and power supply.
6.3
A preliminary layout of the PCB must separate the different circuits according to their electromagnetic interference (EMI) contribution. This reduces cross-coupling on the PCB, for instance, noisy, high-current circuits, low voltage circuits, and digital components.
Ground and power supply (V
SS
, V
DD
)
The V
SS should be distributed individually to every block (noisy, low level sensitive, and digital) with a single point for gathering all ground returns. Loops must be avoided or have a minimum surface. The power supply should be implemented close to the ground line to minimize the surface of the supply loop. This is due to the fact that the supply loop acts as an antenna, and is therefore the main emitter and receiver of EMI. All component-free surfaces of the PCB must be filled with additional grounding to create a kind of shield
(especially when using single-layer PCBs).
6.4 Decoupling
The standard decoupler for the external power is a 100 µF pool capacitor. Supplementary
100 nF capacitors must be placed as close as possible to the V
SS
/V
DD
pins of the microcontroller to reduce the area of the current loop.
As a general rule, decoupling all sensitive or noisy signals improves electromagnetic compatibility (EMC) performances.
There are two types of decouplers:
● Capacitors close to components. Inductive characteristics, which apply to all capacitors beyond a certain frequency, must be taken into account. If possible, parallel capacitors with decreasing values (0.1, 0.01,... µF) should be used.
●
Inductors. Although often ignored, ferrite beads, for example, are excellent inductors due to their good dissipation of EMI energy and there is no loss of DC voltage (which is not the case when simple resistors are used).
18/42 Doc ID 16139 Rev 1
AN3029 Recommendations
6.6
●
●
●
When designing an application, the following areas should be closely studied to improve
EMC performances:
Noisy signals (clock)
Sensitive signals (high impedance)
Signals for which a temporary disturbance permanently affects operation of the application, for example, interrupts and handshaking strobe signals (but not LED commands).
A surrounding V
SS
trace for such signals increases EMC performances, as does a shorter length or absence of noisy and sensitive traces (crosstalk effect).
For digital signals, the best possible electrical margin must be reached for the two logical states. Slow Schmitt triggers are recommended for eliminating parasitic states.
Unused I/Os and features
Microcontrollers are designed for a variety of applications, where often a particular application does not use 100 % of the microcontroller resources.
To avoid unnecessary power consumption (especially important for battery powered applications) and also to improve EMC performance, unused clocks, counters, or I/Os, should not be left free, I/Os should be forced externally (pull-up or pull-down to the unused
I/O pins), and unused functions should be ‘frozen’ or disabled.
Alternatively, unused I/Os can be programmed as push-pull ‘low’ to keep them at a defined level without using external components. However in this case, the I/O is not driven during the power up phase, until the I/O is configured. This can add a little extra power consumption, and may be undesirable in very power sensitive applications.
STM8L devices have user option features that can be used for remapping or enabling/disabling an automatic reset or low speed watchdog. For more details, please refer to the product datasheets.
6.8 Bootloader
STM8L15x devices have a bootloader embedded in a ROM memory. Through this firmware the device memory can be re-programmed via the USART communication interface.
Doc ID 16139 Rev 1 19/42
Reference design AN3029
Table 1.
Component list
ID Component name Reference
1
2
3
4
6
7
8
9
Quantity Comments
Microcontroller STM8L
Battery
Capacitor
Crystal
Capacitor
Crystal
Capacitor
Ferrite bead
1.65 V to 3.6 V
1
1
100 nF n n Ceramic capacitor (decoupling capacitor)
Components below are optional
1 to 16 MHz
20 to 40 pF
32 kHz
5 to 20 pF
SWIM connector 4 pins
1
2
1
2
1
Refer to the ‘pinouts and pin description’ and ‘package characteristics’ sections of the STM8L datasheets, to choose the right package
Min 1.8 V for STM8L15x
Used for crystal
Used for crystal
Depends on noise to be filtered
20/42 Doc ID 16139 Rev 1
AN3029 Reference design
7.2 Schematics
Figure 10.
Reference design
For noisy environment
Only if internal booster is used to power LCD
To power LCD specifi cally
2.5V<VLCD<3.6V
VDD
1uF
OR
For noisy environment
VSS
100 Ohm
100nF
VDD
VSS
3.6V-1.8V
(1.65V)*
1uF
VSS
1uF
100nF
100nF
100nF
Biggest package
VLCD
VDDA
VRef+
VDDIO
NRST
OSC_IN
OSC_OUT
VDD
VSSIO OSC32_IN
VSS/VSSA/VRefOSC32_OUT
VSS
OR
If LCD is unused
VDD
Only if accurate High Speed
Oscillator is needed
0 Ohm
20pF
1-16MHz
20pF
6.8pF
32.768 kHz
0 Ohm
6.8pF
Oscillator is needed
Doc ID 16139 Rev 1 21/42
STM8 development tools
8 STM8 development tools
AN3029
●
●
●
Typically, the following tools are needed to get started:
STVD for integrated development environment
STM8 C compiler (from Cosmic or Raisonance)
ST toolset and STM8 firmware library from STMicroelectronics
(STM8L10x_StdPeriph_Lib for STM8L101 or STM8L15x_StdPeriph_Lib for
STM8L15x).
●
●
STM8 evaluation board from STMicroelectronics (STM8L101-EVAL for STM8L101 and
STM8L1526-EVAL for STM8L15x).
If you use STM8L101-EVAL, you also need the HW debug interface "Rlink" from
Raisonance. The debug interface ST-LINK is included in STM8L1526-EVAL.
8.1 Single wire interface module (SWIM)
In-circuit debugging mode or in-circuit programming mode are managed through a single wire hardware interface based on an open-drain line, featuring ultra fast memory programming. Coupled with an in-circuit debugging module, the SWIM also offers a nonintrusive read/write to RAM and peripherals. This makes the in-circuit debugger extremely powerful and close in performance to a full-featured emulator.
The SWIM pin can be used as a standard I/O (with 8 mA capability) which has some restrictions if the user wants to use it for debugging. The most secure way to use it is to provide a strap option on the PCB. Please refer to the STM8 SWIM communication protocol and debug module user manual (UM0470) for more SWIM protocol details.
Figure 11.
Debug system block diagram
DBG
100 kHz Osc
SWIM entry
Comm layer
CMD decode
Internal RC
DM
STM8 core
Peripheral
RAM
NVM
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8.1.2
STM8 development tools
SWIM connector pins
The SWIM connector pins consist of four pins as described in
.
Table 2.
SWIM connector pins
Pin number
Pin 1
Pin 2
Pin 3
Pin 4
Pin name
V
DD
SWIM pin
V
SS
Reset
Figure 12.
Hardware connection
AD/ICC SWIM adapter
SWIM connector
V
DD 1
2
3
4
Application board
1
2
3
4
V
DD
STM8
SWIM cable
Caution:
It is recommended to place the SWIM header as close as possible to the STM8L device, as this minimizes any possible signal degradation caused by long PCB tracks.
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STM8 development tools AN3029
The STice is a modular, high-end emulator system which connects to the PC via a USB interface, and to the application board in place of the target microcontroller.
It is supported by the free STM8 toolset: IDE ST visual develop (STVD) programmer, ST visual programmer (STVP) and STM8 assembler. Please refer to the STice emulator for
STM8 for more details.
STice has two distinct modes of operation which are described further in this section:
●
●
Emulation mode
In-circuit mode
It can also be used instead of RLink for SWIM connection.
Figure 13.
Connection description
Emulation system
Connection flex
Connection adapter
Adapter socket
Emulation system: STice
●
●
Emulator box
Cables for USB, power supply, trigger, and analyzer input
Connection flex
● 60-pin or 120-pin cable for connection to the application board
Connection adapter
● Links the connection flex to the footprint of the STM8L microcontroller
Adapter socket
● Package-specific socket for connection adapter and STM8L microcontroller
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8.2.2 STice in emulation configuration
In emulation configuration, the STice is connected to the PC via a USB interface and to the application board in place of the target microcontroller being used.
●
Connection flex: Flexible cable (60-pin or 120-pin depending on the target microcontroller) that relays signals from the STice to the application board.
● Connection adapter: Links the connection flex to the footprint of the target microcontroller on the users application board.
●
Adapter socket: Socket that solders to the application board in place of the microcontroller and receives the connection adapter.
The above accessories are not included with the STice system. To determine exactly what
is required for any supported microcontroller, refer to the online product selector on
www.st.com
.
Figure 14.
STice in emulation configuration
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STM8 development tools
8.2.3
AN3029
In-circuit programming and debugging
In the in-circuit debugging/programming configuration, STice allows the application to be programmed in the microcontroller and for the application to be debugged while it runs on the microcontroller on the application board. STice supports the SWIM protocol, making it possible to in-circuit program and debug the microcontroller using only one general purpose
I/O.
In both the emulation and the in-circuit programming/debugging configuration, STice is driven by the ST visual develop (STVD) or ST visual programmer (STVP) integrated development environment running on the host PC. This provides total control of advanced application building, debugging and programming features from a single easy-to-use interface.
Figure 15.
In-circuit programming and debugging
8.3 RLink STLink
RLink and STLink are debug tools that allow the STM8L evaluation board or any user application board with the SWIM interface to be connected to a host PC via USB for
debugging and programming. See
Section 10.3.3: Connecting the hardware on page 35
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9 STM8 software toolchain
STM8 software toolchain
●
●
●
To write, compile and run the first software on an STM8L device, the following components of the software toolchain are required (see
):
Integrated development environment
Compiler
Firmware library (optional, used to ease the start-up)
Figure 16.
STM8 software toolchain
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STM8 software toolchain
9.1
AN3029
Integrated development environment
The integrated development environment ST visual develop (STVD) provides an easy-touse, efficient environment for start-to-finish control of application development, from building and debugging the application code to programming the microcontroller. STVD is delivered as part of the free ST toolset, which also includes the ST visual programmer (STVP) programming interface and the ST assembler linker.
To build applications, STVD provides seamless integration of C and assembly tool chains for
ST including the Cosmic and Raisonance C compilers and the ST assembler linker. When debugging, STVD provides an integrated simulator (software) and supports a complete range of hardware tools including the low-cost RLink in-circuit debugger/programmer and the high-end STice emulator.
To program applications to an STM8L, the STVD also provides an interface for reading from the microcontroller memories, writing to them and verifying them. This interface is based on the ST visual programmer (STVP), and supports all the target devices and programming tools supported by STVP.
The free ST toolset for STM8 is available from STMicroelectronics homepage (see
www.st.com
).
9.2 Compiler
STM8L devices can be programmed by a free assembler toolchain which is included in the
ST toolset.
As the core is designed for optimized high-level-language support, use of a C compiler is recommended!
C compilers for STM8 are offered by the third party companies Cosmic and Raisonance.
A free version of the C compiler with up to 16 Kbytes of generated code is available at: www.cosmic-software.com and www.raisonance.com.
The STM8 firmware library is a complete set of source code examples for each STM8 peripheral. It is written in strict ANSI-C and it is fully MISRA C 2004 compliant.
All examples are delivered with three workspace and project definition files,one for STVD and Cosmic C compiler, one for STVD and raisonance Compiler, and one for Raisonance integrated debugging environment and compiler. This enables the user to load and compile them easily into their preferred development environment.
The examples run on the STMicroelectronics STM8L evaluation board and can be tailored easily to other types of hardware.
For additional information and download of the STM8L firmware library connect to www.st.com/mcu.
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10
Setting up the STM8 development environment
Setting up the STM8 development environment
The STM8 development environment setup looks different depending on the supplier of the software (SW) and hardware (HW) tools.
●
●
Typical setups are described below for the following SW and HW tools:
STM8 C compiler from Cosmic
ST toolset and STM8 firmware library from STMicroelectronics
(STM8L10x_StdPeriph_Lib for STM8L101 or STM8 L 15x_StdPeriph_Lib for
STM8L15x).
● STM8 evaluation board from STMicroelectronics (STM8L101-EVAL for STM8L101 and
STM8L1526-EVAL for STM8L15x).
●
If you use STM8L101-EVAL, you also need the HW debug interface "Rlink" from
Raisonance. The debug interface ST-LINK is included in STM8L1526-EVAL.
10.1 Installing tools
All software tools are delivered with a setup wizard which guides the user through the installation process. It is recommended to install the tools in the following order:
1.
C compiler
ST-LINK does not need any dedicated software installation in the STM8 development environment because the necessary drivers are delivered with the ST toolset.
The R-link drivers must be launched separately as follows:
Start/Programs/STtoolset/Setup/Install Rlink driver.
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Setting up the STM8 development environment AN3029
10.2 Using tools
Note:
Once the tools installation is complete, the ST visual develop (STVD) integrated development environment can be launched.
The user then has the choice to generate either a new workspace with a new project or to open an existing workspace. If using the STVD for the first time, it is recommended to open an existing project from the STM8 firmware library.
Even if you are not intending to use the library, an existing library project can be used as a template to configure all the compiler options. Enter your own code after main().
The STM8 firmware library includes several examples for each peripheral plus one workspace containing a blank project which is ready to receive your C code. It is located in
the firmware subdirectory \Project\Template (see
STVD\Cosmic, STVD\Raisonance, or RIDE.
Figure 17.
STVD open example workspace
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All project source files are visible and can be edited (see
).
Figure 18.
STVD MCU edit mode
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Setting up the STM8 development environment AN3029
An online help manual is available inside the firmware installation directory (see
) to help the user understand the structure of the STM8 firmware library.
Figure 19.
STM8 firmware library online help manual
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10.3 Running the demonstration software
●
●
●
Go to www.st.com/mcu and search for STM8L products
Choose STM8L1x-EVAL or STM8L1526-EVAL firmware
Open the project/demo/STVD/Cosmic/project.stw
To run the demonstration software on the STM8 evaluation board, the project has to be compiled and the correct HW tool must be selected before the debug session can be started.
10.3.1 Compiling the project
The project can be compiled using the ‘Build’ function in the ‘Build’ menu (see
).
Figure 20.
STVD: Building the project
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10.3.2 Selecting the correct debug instrument
In the example below, the Rlink tool is used for communicating via the SWIM interface with the on-board debug module of the STM8.
The Rlink tool can be selected from the ‘Debug Instrument Selection’ list in the ‘Debug
Instrument Settings’ dialog (see
Figure 21.
STVD: Selecting the debug instrument
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The debug tool, STLink, is included on the STM8L1526-EVAL board. You can connect the
PC to the USB connector. This connection ensures the debug connection and the power. If the jumpers on the boards are no longer in the default position, please read STM8L1526-
EVAL user manual to select power and debug support jumpers.
For the STM8L101-EVAL, the Rlink tool can be connected to the PC by a standard USB connection. It is also powered by the USB interface. On the controller side, the connection to the STM8 evaluation board is made using the SWIM interface cable. The STM8L101-EVAL, evaluation board is powered by an external 5 V supply (see
).
Figure 22.
Connecting the debug instrument to the STM8L101-EVAL evaluation board
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Setting up the STM8 development environment AN3029
Figure 23.
Connecting the debug instrument to the STM8L15x-EVAL evaluation board
Caution:
On the Rlink adapter board for STM8, the “SWIM” jumper must be set. If there is no pull-up on the application SWIM line, the “ADAPT” jumper is also set. The “PW-5V” and “12MHz” jumpers must not be set.
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10.3.4 Starting the debug session
Debug mode can be entered by the command ‘Debug Start Debugging’ (see
Figure 24.
STVD: Starting the debug session
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Setting up the STM8 development environment AN3029
After entering debug mode, the software can be started by the run command in the menu ‘Debug Run’
Figure 25.
STVD: Run the software
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The LCD display on the STM8 evaluation board indicates a successful debug session (see
).
Figure 26.
STM8 evaluation board
Step by step, additional peripherals of STM8L devices can be run, following on from the initial debug session described above.
Many features of STM8L devices are supported by dedicated hardware on the STM8 evaluation board. The necessary software drivers, including STM8L peripheral drivers
(USART, ADC, SPI) and drivers for the EVAL board modules (LCD, serial memory), are delivered in the STM8L1x firmware library.
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Documentation and online support
11 Documentation and online support
AN3029
Documentation resources related to tool usage includes:
●
●
Application
●
●
STM8L101 and STM8L15x datasheets
How to program Flash memory and data EEPROM on STM8L microcontrollers
(PM0054).
STM8L101 and STM8L15x reference manuals
STM8 CPU programming manual (PM0044)
Tools
●
●
●
●
●
●
●
●
●
STM8L101 and STM8L15x firmware library and release note (detailed descriptions of the library are included as help files).
STice advanced emulation system for ST microcontrollers data briefing
STice user manual
Cosmic or Raisonnance C compiler user manual
STM8L101-EVAL or STM8L1526-EVAL evaluation board user manual
STM8L1x-EVAL or STM8L1526-EVAL firmware
ST visual develop tutorial (included as help files in the ST-toolchain)
ST visual develop (STVD) user manual
STM8 SWIM communication protocol and debug module user manual (UM0470)
The microcontroller discussion forum on
www.st.com
can be used by developers to exchange ideas. It is the best place to find different application ideas. In addition, the website has a knowledge base of FAQs for microcontrollers, which provide answers to many queries and solutions to many problems.
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Table 3.
Date
Document revision history
Revision
09-Sep-2009 1 Initial release
Changes
Revision history
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Key Features
- analog-to-digital converter (ADC)
- clock management
- reset control
- low power modes
- single wire interface module (SWIM)
- integrated development environment
- firmware library
- evaluation board
- programming tools
- debugging tools