STMicroelectronics STM8S microcontroller Application note
Below you will find brief information for microcontroller STM8S. This document contains information about the minimum hardware and software environment required to build an application around a STM8S 8-bit microcontroller device. It is divided into the following sections: Power supply, Analog-to-digital converter (ADC), Clock management, Reset control and development, Debugging tool support, STM8 software toolchain, Setting up the STM8 development environment. This document also contains detailed reference design schematics with descriptions of the main components. In addition, some hardware recommendations are given.
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AN2752
Application note
Getting started with the STM8S
Introduction
■
■
■
■
■
■
■
This application note complements the information in the STM8S datasheets by describing the minimum hardware and software environment required to build an application around an
STM8S 8-bit microcontroller device. It is divided into the following sections:
Power supply
Analog-to-digital converter (ADC)
Clock management
Reset control and development
Debugging tool support
STM8 software toolchain
Setting up the STM8 development environment
This application note also contains detailed reference design schematics with descriptions of the main components. In addition, some hardware recommendations are given.
September 2008 Rev 2 1/42
www.st.com
Contents
Contents
2/42
AN2752
Hardware requirements summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Power-on/power-down reset (POR/PDR) . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Analog-to-digital converter (ADC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Clock management overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Reset management overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Hardware reset implantation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
SS
, V
DD
) . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Unused I/Os and features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
AN2752
Contents
STM8 development tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Single wire interface module (SWIM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
SWIM connector pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Hardware connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
STice in emulation configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
In-circuit programming and debugging . . . . . . . . . . . . . . . . . . . . . . . . . 25
STM8 software toolchain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Integrated development environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Setting up the STM8 development environment . . . . . . . . . . . . . . . . . 30
Running the demonstration software . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Selecting the correct debug instrument . . . . . . . . . . . . . . . . . . . . . . . . . 35
Connecting the hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Starting the debug session . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Documentation and online support . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
3/42
List of tables
List of tables
AN2752
4/42
AN2752
List of figures
List of figures
DD
/V
SS
pair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5/42
Hardware requirements summary
1 Hardware requirements summary
AN2752
●
●
●
●
In order to build an application around an STM8S device, the application board should, at least, provide the following features:
Power supply
Clock management
Reset management
Debugging tool support: Single wire interface module (SWIM) connector
6/42
AN2752 Power supply
2.1
Note:
Note:
Power supply overview
The device can be supplied through a 3.0 V to 5.5 V external source. An on-chip power management system provides the 1.8 V digital supply to the core logic, both in normal and low power modes. It is also capable of detecting voltage drops, on both main external (3.3
V/5 V) and internal (1.8 V) supplies.
The device provides:
●
One pair of pads V
DD
/V
SS ballast transistor supply.
(3.3 V ± 0.3 V to 5 V ± 0.5 V) dedicated to the main regulator
● Two pairs of pads dedicated for V
DD_IO
/V
SS_IO
(3.3 V ± 0.3 V to 5 V ± 0.5 V), which are used to power only the I/O’s. On 32-pin packages, only one pair is bonded.
For V
DDIO
/V
SSIO
next to V
DD
/V
SS
, it is recommended to connect these two pairs together and to use only one decoupling capacitance. The purpose is to ensure good noise immunity by reducing the connection length between both supplies and also between V
DD the capacitor.
/V
DDIO
and
●
One pair of pads V
DDA
/V
SSA
(3.3 V ± 0.3 V to 5 V ± 0.5 V) dedicated to analog functions. Refer to
Section 3: Analog-to-digital converter (ADC) on page 10
details.
Figure 1.
Power supply
Analog signal
V
DDA
V
SSA
V
CAP
V
DD
/V
DDIO1
Analog functions
V
SS
/V
SSIO1
V
DDIO2
Main / Low power regulator
CPU
RAM
Logic
V
SSIO2
OSCIN
V
DDIO
V
SSIO
V
DDIO
V
SSIO
XTAL
Star connected
OSCOUT ai15330
The capacitors must be connected as close as possible to the device supplies (especially
V
DD
in case of dedicated ground plane).
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
.
7/42
Power supply
2.2
AN2752
Main operating voltages
STM8S devices are processed in 0.13 µm technology. The STM8S core and I/O peripherals need different power supplies. In fact, STM8S devices have an internal regulator with a nominal target output of 1.8 V.
Stabilization for the main regulator is achieved using an external capacitor via the V
CAP
pin.
The typical value is 470 nF with low equivalent series resistance (ESR). Care should be taken to limit the series inductance per pad to less than 15 nH.
Figure 2.
External capacitor
ESR C ESL
Rleak
Where:
ESR is the equivalent series resistance
ESL is the equivalent inductance
The typical value of C is 470 nF with an ESR between 0.05...0.2 Ohm
The input supply to the main and low power regulators is monitored by a power-on/powerdown reset circuit. The monitoring voltage range is 0.7 V to 2.7 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.
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 datasheet.
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).
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 STM8S 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.
8/42
AN2752
Figure 3.
Typical layout of V
DD
/V
SS
pair
Via to V
DD
Cap
.
Via to V
SS
Power supply
V
DD
V
SS
STM8
9/42
Analog-to-digital converter (ADC) AN2752
The ADC unit has an independent, analog supply reference voltage, isolated on input pin
V
DDA
, which allows the ADC to accept a very clean voltage source. This analog voltage supply range is the same as the digital voltage supply range on pin V
DD
. An isolated analog supply ground connection on pin V
SSA
provides further ADC supply isolation. Together, the analog supply voltage and analog supply ground connection, offer 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 between [250 mV, V
DDA
]. For more details about V
REF+
values please refer to the STM8S20xxx datasheet. This input is bonded to V
DDA
in devices that have no external V
REF+
pin (packages with 48 pins or less).
V
REF-
(input, analog reference negative): The lower/negative reference voltage for the
ADC should be higher than V
SSA
. For more details about V
REF-
values please refer to the STM8S20xxx datasheet. This input is bonded to V
SSA
in devices that have no external V
REF-
pin (packages with 48 pins or less).
STM8S20xxx devices have 16 analog input channels, which are converted by the ADC one at a time, and each multiplexed with an I/O.
The analog input interface of the ADC is shown in
Figure 4.
Analog input interface
Inside ADC
V
IN_EXT
Outside ADC
R
EXT
V
IN
SW
SAMP
C
EXT
C
SAMP
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AN2752 Analog-to-digital converter (ADC)
Equation 1:
C
VIN
= C
SAMP
+ C
EXT where:
●
●
●
C
VIN
is the total equivalent capacitor on the path of V
IN
C
SAMP
is the equivalent sampling capacitance
C
EXT
is the total external capacitance on the path of V
IN
to the macro pin. This includes parasitic routing capacitance, pad and pin capacitance and external capacitance. To ensure proper and accurate sampling the following equation must be satisfied
Equation 2:
(
R
SW
+ R
EXT
) × (
C
SAMP
+ C
EXT
) <
⎛ ⎞
10
×
T
S where:
●
●
●
●
R
SW
= 30 kOhm
R
EXT
is the total external resistance on the path of V
IN
C
SAMP
= 3 pF
T
S
= 0.5 µs (for 2 MHz input CLK)
EXT
and C
EXT
ADC.
when designing an analog input interface for the
Please refer to the STM8S20xxx datasheet and/or the corresponding family reference manual (RM0016) for more details.
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Clock management AN2752
4.1 Clock management overview
STM8S20xxx devices offer a flexible way of selecting the core and peripheral clocks (ADC, memory, digital peripherals). The devices have internal and external clock source inputs and one output clock (CCO).
Figure 5.
System clock distribution internal clock
OSC
IN
1 to 24 MHz crystal and external clock
External clock OSC
OUT
Clock unit
CCO pin
16 MHz/128 kHz internal RC
Prescaler
WDG/AWU
Timer
Clock distribution lnternal clock
For more details please refer to the section on clock management in the datasheet
The RC oscillator has an internal capacitor (C) and an internal resistor ladder (R). STM8S 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 128 kHz.
After reset, the CPU starts with the internal RC (HSI clock signal) divided by 8, i.e. 2 MHz.
Note:
STM8S 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.
12/42
AN2752 Clock management
Figure 6.
Clock sources
Hardware configuration
OSC
IN
STM8
OSC
OUT
(I/O available)
External source
Frequency: 32 kHz … 24 MHz
Comparator hysteresis: 0.1 * V
DD
Caution: Without prescaler, a duty cycle of maximum 45/55% must be respected
OSC
IN
STM8
OSC
OUT
Q1
C
L1
C
L2
Load capacitors
Frequency range: 1-24 MHz
Wake-up time: < 2 ms @ 24 MHz
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 … 20 pF
Maximum crystal power: 100 µW
The values of the load capacitors C
L1
and C
L2
are heavily dependent on the crystal type and frequency. The user can 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 … 20 pF). The parasitic capacitance of the board layout also needs to be considered and typically adds a few pF to the component values.
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.
13/42
Reset control AN2752
5.1 Reset management overview
The reset cell is a dedicated 5 V bidirectional I/O. Its output buffer driving capability is fixed to Iol
MIN
= 2 mA @ 0.4 V in the 3 V to 5.5 V range which includes a 40 k pull-up. Output buffer is reduced to the n-channel MOSFET (NMOS). If a 40 k pull-up is accepted, this cell does not include an output buffer of 5 V capability. 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 the BOR starts to function.
Independent watchdog reset (IWDG)
Window watchdog reset (WWDG)
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
Figure 7.
Reset management
STM8
Simplified functional I/O reset schematic
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
14/42
AN2752 Reset control
Output characteristics
●
●
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 ns
A
20 µs pulse stretch min.
Pad
Reset requested
●
●
Input characteristics
●
●
All pulses with a duration less than 75 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 75 ns is always filtered, when a 7.5 ns interval between spikes occurs
(ratio 1/10).
All pulses with duration more than 450 ns are recognized as valid pulses
After a valid pulse is recognized, an internal pulse of at least 30 ns is guaranteed
Figure 9.
Input characteristics
>7.5 ns >7.5 ns
450 ns
Pad
<75 ns <75 ns <75 ns
Negative train of glitch filtered
>30 ns
Reset requested
System reset
There are several reset implementation schemes to choose from, such as power supply behavior, based on the specific parameters of the application. Whatever the solution chosen, the idea is to keep the RESET pin at a low logic level until the supply has reached a safe operating voltage. Therefore, the external circuit should be designed in such a manner that there is enough delay to keep the RESET pin below the V
IL
value.
15/42
Reset control AN2752
The RC circuit concept is the simplest and most cost-effective external reset solution, where the supply waveform is monotonous and the maximum rise time is known. The principle is to let the RESET pin rise with the microcontroller supply voltage after a delay. The circuit is
.
The basic solution is to use an RC delay determined by the rise rate of the supply itself. The component values must be chosen to create enough delay to keep the RESET pin below the
V
IL
specification until V
CC
reaches a safe operating voltage. Normally, a delay (time constant) corresponding to at least 30 % of the total rise time is advised.
Figure 10.
RC circuit
STM8
VDD_IO
R
PU
NRSTIN
Push button C1 100nF
The RC circuit scheme requires a certain delay between a power-down and the next powerup, because the delay generator has to be reinitialized. In practice, a pull-down capacitor between RESET and V
SS needs to be discharged.
16/42
AN2752
6 Recommendations
6.1
Recommendations
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, which 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 in order to reduce cross-coupling on the
PCB, i.e. 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 micro in order 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 2 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).
17/42
Recommendations AN2752
6.6
●
●
When designing an application, the following areas should be closely studied to improve
EMC performances:
Noisy signals (clock)
Sensitive signals (high impedance)
In addition to:
● 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 2 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 increase EMC performance, unused clocks, counters, or I/Os, should not be left free, for example, I/Os should be set to ‘0’ or ‘1’ (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’ in order to keep them at a defined level but not to use external components.
STM8S 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 datasheet.
18/42
AN2752 Reference design
Table 1.
ID
Component list
Component name Reference Quantity
1 Microcontroller STM8S 1
Comments
Refer to the ‘Pinouts and pin description’ and ‘Package characteristics’ sections of the STM8S20xxx datasheet, to choose the right package
2 Push button 1 1
3 Resistor 10 1
4 Capacitor 100 nF 5
5 Capacitor 1 µF 1
6 Capacitor
7 Capacitor
8 Crystal
9 SWIM connector
470 nF
20..40 pF
1..24 MHz
4 pins
1
2
1
1
Ceramic capacitor (decoupling capacitor)
Decoupling capacitor
Main regulator stabilization
Used for crystal
19/42
Reference design AN2752
7.2 Schematics
Figure 11.
Reference design
C5
100 nF
B1
100 nF
C1
Reset
C6
100 nF
VDD
2)
C7
100 nF
20 pF
Clock(H SE)
CN1
4
3
2
1
SW IM connector
Debug
VDD
2)
C8
100 nF
Decoupling Capacitor
C2
20 pF
C3
C9
1 µF
X1
470 nF
VDD
2)
PA0
PA1
PA2
VCAP
C4
8
49
7
23
5
24
4
48
77
78
79
80
73
74
75
76
46
47
50
51
42
43
44
45
34
33
32
31
30
29
28
27
10
11
12
6
3
9
1
2
U1 STM8 Package L QF P 80- pin
NRST
PA1/OSCIN
PA2/OSCOUT
PA3/TIM2_CH3[TIM3_CH1]
PA4/UART1_RX
PA5/UART1_TX
PA6/UART1_CK
VCAP
PE0/CLK_CCO
PE1/I 2C_SCL
PE2/I 2C_SDA
PE3/TIM1_BKIN
PE4
PE5/SP I_NSS
PE7/AIN8
PE6/AIN9
PB0/AIN0[TIM1_CH1N]
PB1/AIN1[TIM1_CH2N]
PB2/AIN2[TIM1_CH3N]
PB3/AIN3[TIM1_ETR]
PB4/AIN4[I2C_SCL]
PB5/AIN5[I2C_SDA]
PB6/AIN6
PB7/AIN7
PF0/AIN10
PF1/VREF -
PF2/VREF +
PF3/AIN11
PF4/AIN12
PF5/AIN13
PF6/AIN14
PF7/AIN15
PC0/ADC_ ETR
PC1/TIM1_CH1
PC2/TIM1_CH2
PC3/TIM1_CH3
PC4/TIM1_CH4
PC5/SPI_SCK
PC6/SPI_MOSI
PC7/SPI_MI SO
PG0/CAN_TX
PG1/CAN_RX
PG2
PG3
PG4
PG5
PG6
PG7
PD0/TIM3_CH2[TIM1_BKIN][CLK_CCO]
PD1/SWIM
PD2/TIM3_CH1[TIM2_CH3]
PD3/TIM2_CH2[ADC_ETR]
PD4/TIM2_CH1[BEE P]
PD5/UART3_TX
PD6/UART3_RX
PD7/TL I[TIM1_CH4]
PH0
PH1
PH2
PH3
PH4/TI M1_ETR
PH5/TIM1_CH3N
PH6/TIM1_CH2N
PH7/TIM1_CH1N
VDDIO_1
VDDI O_2
VDD
VDDA
VSS
VSSA
VSSIO_1
VSSIO_2
PI0
PI1
PI2
PI3
PI4
PI5
PI6
PI7
MCU
61
62
71
72
57
58
59
60
70
69
68
67
66
41
40
39
26
25
22
21
20
19
18
17
PF1
PF2
56
63
64
65
52
53
54
55
35
36
37
38
13
14
15
16
R1
R2
0
0 1)
VDD
2)
[ ] alternate function remapping option (If the same alternate function is shown twice, it indicates an exclusive choice not a duplication of the function).
1.
If pins 22 or 25 are required as GPIO, R1 and R2 should be removed.
2.
V
DD
must be within the allowed supply voltage range of the STM8S microcontroller.
ai15471B
20/42
AN2752 Reference design
7.3 Pinouts
STM8S devices have several package types, including the LQFP 80-pin pinout shown in
. Please refer to the STM8S20xxx datasheet for more details.
Figure 12.
LQFP 80-pin pinout
NRST
OSCIN/PA1
OSCOUT/PA2
V
SSIO_1
V
SS
VCAP
V
DD
V
DDIO_1
[TIM3_CH1]TIM2_CH3/PA3
UART1_RX/PA4
UART1_TX/PA5
UART1_CK/PA6
(HS) PH0
(
HS) PH1
PH2
PH3
AIN15/PF7
AIN14/PF6
AIN13/PF5
AIN12/PF4
10
11
12
13
14
6
7
8
9
3
4
5
1
2
15
16
17
18
19
20
60
59
58
57
56
55
54
53
52
51
50
49
48
47
46
45
44
43
42
41
PI3
PI2
PI1
PI0
PG4
PG3
PG2
PG1/CAN_RX
PG0/CAN_TX
PC7/SPI_MISO
PC6/SPI_MOSI
V
DDIO_2
V
SSIO_2
PC5/SPI_SCK
PC4 (HS)/TIM1_CH4
PC3 (HS)/TIM1_CH3
PC2 (HS)/TIM1_CH2
PC1 (HS)/TIM1_CH1
PC0/ADC_ETR
PE5/SPI_NSS
(HS) High sink capability
1.
(HS) high sink capability.
2.
[ ] alternate function remapping option (If the same alternate function is shown twice, it indicates an exclusive choice not a duplication of the function).
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STM8 development tools
8 STM8 development tools
AN2752
Development tools for STM8S microcontrollers include the STice emulation system supported by a complete software tool package including C compiler, assembler and integrated development environment with high-level language debugger.
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 13.
Debug system block diagram
DBG
100 kHz Osc
SWIM entry
Comm layer
CMD decode
Internal RC
DM
STM8 core
Peripheral
RAM
NVM
8.1.2 SWIM connector pins
The SWIM connector pins consist of 4 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
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AN2752 STM8 development tools
Figure 14.
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 STM8S device, as this minimizes any possible signal degradation caused by long PCB tracks.
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.
Figure 15.
Connection description
Emulation system
Connection flex
Connection adapter
Adapter socket
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STM8 development tools AN2752
Emulation system: STice
●
●
Emulator box
Cables for USB, power supply, trigger, 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 STM8S microcontroller
Adapter socket
● Package-specific socket for connection adapter and STM8S microcontroller
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
.
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AN2752
Figure 16.
STice in emulation configuration
Free ST/STM8 toolset: STVD and STVP running on your PCdrive STice
STM8 development tools
AD/xxxx: Connection adapter to link connection cable to microcontroller
STice-SYSxxx: Includes all emulation resources, MEB, TEB, and PEB
CF/FPxxx: Connection flex to connect to application board
AS/xxxx: Adapter socket on application board to plug in emulator in place of microcontroller
8.2.3 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.
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STM8 development tools
Figure 17.
In-circuit programming and debugging
ICD/ICP flat cable connects STice to microcontroller via
ICD/ICP connector on application board for ST)
ST microcontroller on application board
AN2752
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AN2752
9 STM8 software toolchain
STM8 software toolchain
●
●
●
In order to write, compile and run the first software on an STM8S 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 18.
STM8 software toolchain
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STM8 software toolchain
9.1
AN2752
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 STM8S, 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
STM8S 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.
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AN2752 STM8 software toolchain
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 (see
).
All examples are delivered with workspace and project definition files for STVD and Cosmic
C compiler which enables the user to load and compile them easily into the development environment.
The examples run on the STMicroelectronics STM8 evaluation board and can be tailored easily to other types of hardware.
For additional information on the STM8 firmware library, please contact STMicroelectronics.
Figure 19.
STM8 firmware library examples
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Setting up the STM8 development environment
10 Setting up the STM8 development environment
AN2752
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
HW debug interface "Rlink" from Raisonance
STM8 evaluation board from STMicroelectronics
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
Note:
The Rlink does not need any dedicated software installation in the STM8 development environment because the necessary drivers are delivered with the ST toolset.
These R-link drivers must be launched separately as follows:
Start/Programs/STtoolset/Setup/Install Rlink driver.
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AN2752 Setting up the STM8 development environment
10.2 Using tools
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.
The STM8 firmware library includes several examples for each peripheral plus one workspace containing a project which is already configured for the dot-matrix-display of the
STM8 evaluation board. It is located in the firmware subdirectory \Project\Cosmic (see
).
Figure 20.
STVD open example workspace
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Setting up the STM8 development environment
All project source files are visible and can be edited (see
).
Figure 21.
STVD MCU edit mode
AN2752
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AN2752 Setting up the STM8 development environment
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 22.
STM8 firmware library online help manual
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Setting up the STM8 development environment AN2752
10.3 Running the demonstration software
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 23.
STVD: Building the project
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AN2752 Setting up the STM8 development environment
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 24.
STVD: Selecting the debug instrument
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Setting up the STM8 development environment AN2752
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 by the SWIM interface cable. The STM8 evaluation board is powered by an external 5 V supply (see
).
Figure 25.
Connecting the debug instrument to the STM8 evaluation board
Rlink USB connection
Rlink adapter for STM8
SWIM interface connection
5 V power supply
Caution:
On the Rlink ICC/SWIM adapter board, the “SWIM” jumper must be set.
If there is no pull-up on the application SWIM line, the “ADAPT” jumper is also set.
In any case, “PW-5V” and “12MHz” jumpers must not be set.
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AN2752 Setting up the STM8 development environment
10.3.4 Starting the debug session
Debug mode can be entered by the command ‘Debug Start Debugging’ (see
Figure 26.
STVD: Starting the debug session
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Setting up the STM8 development environment AN2752
After entering debug mode, the software can be started by the run command in the menu ‘Debug Run’
Figure 27.
STVD: Run the software
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AN2752 Setting up the STM8 development environment
The LCD display on the STM8 evaluation board indicates a successful debug session (see
).
Figure 28.
STM8 evaluation board
Step by step, additional peripherals of STM8S devices can be run, following on from the initial debug session described above.
Many features of STM8S devices are supported by dedicated hardware on the STM8 evaluation board. The necessary software drivers (CAN driver, LIN driver, buttons, memory cards, buzzer, etc) are delivered in the STM8 firmware library.
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Documentation and online support
11 Documentation and online support
AN2752
Documentation resources related to tool usage includes:
Application
●
●
●
●
STM8S20xxx datasheet
STM8 Flash programming manual (PM0051)
STM8S Family reference manual (RM0016)
STM8 CPU programming manual (PM0044)
Tools
●
●
●
●
●
●
●
●
STM8 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 C compiler user manual
STM8/128-EVAL evaluation board user manual (UM0482)
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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AN2752 Revision history
Table 3.
Date
03-Jun-2008
Document revision history
01-Sep-2008
Revision
1
2
Changes
Initial release
STM8S207/208 replaced by STM8S20xxx
Figure 11: Reference design on page 20
Figure 12: LQFP 80pin pinout on page 21
modified to be in line with the pin description of
Figure 7: Reset management on page 14 modified
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AN2752
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Key features
8-bit microcontroller
Analog-to-digital converter (ADC)
Clock management
Power supply
Reset management
Debugging tool support
STM8 firmware library
STM8 software toolchain
Reference design schematics
Hardware recommendations
Frequently asked questions
You will need power supply, an analog-to-digital converter (ADC), clock management, reset control, debugging tool support, an STM8 software toolchain, and a development environment.
STM8S devices have an internal regulator with a nominal target output of 1.8 V. The main regulator needs an external capacitor for stabilization, typically 470 nF with low equivalent series resistance (ESR).
The VCAP pin is used to connect an external capacitor for stabilizing the internal regulator that provides the 1.8 V digital supply to the core logic.
The STM8S device supports multiple reset sources, including external reset through NRST pin, power-on and brown-out reset, watchdog reset, software reset, SWIM reset, illegal opcode reset, and electromagnetic susceptibility (EMS) reset.