A Close up look

The Stm8s-Discovery is an ultra cheap development / demo board for the STM8 8 bit micro controller , which can be picked up for as little as £6 in the UK.

The Stm8s-Discovery consists of two parts , the embedded ST-LINK programmer/debugger on the left and a STM8S105C6T6 micro controller as the target device on the right hand side.
There is also a handy prototyping area and all of the STM8S105C6T6 48 pins are available on the 4x 12 pin headers.

The board can be snapped apart leaving the ST-LINK programmer/debugger separate which then can be used again to reprogram the STM8S105C6T6 by using interconnecting leads between the two boards. The ST-LINK programmer/debugger can also be used to program/debug other STM8 devices via the SWIM and RST pins.

The Stm8 target board has selectable 3.3v or 5v power , a LED attached to one of the GPIO pins and a capacitive touch sensor which uses a further 3 GPIO pins but they can be disconnected via solder bridges. A 16mhz Crystal external clock makes up the rest of the hardware. The stm8 does not need an external clock and can run on its internal 16mhz rc clock but with less accuracy.

If we take a look at the ST-LINK programmer/debugger we see that it is a even more advanced STM32F103  32bit ARM based chip

Interestingly there is place for a JTAG socket on the ST-LINK part.

Which should allow the reprogramming of the STM32F103 , which would be handy to make use of all the spare ST-LINK programmer/debugger boards.

Discovery Board Features

■ STM8S105C6T6 microcontroller, 32 KB Flash, 2 KB RAM, 1 KB EEPROM

■ Powered by USB cable between PC and STM8S-DISCOVERY

■ Selectable power of 5 V or 3.3 V

■ Touch Sensing button, TS1

■ User LED, LD1

■ Extension header for all I/Os

■ Wrapping area for users own application

■ Embedded ST-LINK for STM8S

■ USB interface for programming and debugging

■ SWIM debug support

The STM8S105C6T6 Micro controller

• 16 MHz advanced STM8 core with Harvard architecture and 3-stage pipeline and Extended instruction set

• Medium-density Flash/EEPROM: - Program memory up to 32 Kbytes; data retention 20 years at 55°C after 10 kcycles - Data memory up to 1 Kbytes true data , EEPROM; endurance 300 kcycles

• RAM: 2 Kbytes

• 2.95 V to 5.5 V operating voltage

• Flexible clock control, 4 master clock sources: - Low power crystal resonator oscillator - External clock input - Internal, user-trimmable 16 MHz RC - Internal low power 128 kHz RC

• Clock security system with clock monitor

• Power management: - Low power modes (wait, active-halt, halt) - Switch-off peripheral clocks individually

• Permanently active, low consumption power-on and power-down reset

• Nested interrupt controller with 32 interrupts

• Up to 37 external interrupts on 6 vectors Timers

• 2x 16-bit general purpose timers, with 2+3 CAPCOM channels (IC, OC or PWM)

• Advanced control timer: 16-bit, 4 CAPCOM channels, 3 complementary outputs, dead-time insertion and flexible synchronization

• 8-bit basic timer with 8-bit prescaler

• Auto wake-up timer

• Window and independent watchdog timers Communications interfaces

• UART with clock output for synchronous operation, Smartcard, IrDA, LIN

• SPI interface up to 8 Mbit/s

• I2C interface up to 400 Kbit/s

• 10-bit, ±1 LSB ADC with up to 10 multiplexed channels, scan mode and analog watchdog

• Up to 38 I/Os on a 48-pin package including 16 high sink outputs

• Highly robust I/O design, immune against current injection

• Embedded single wire interface module (SWIM) for fast on-chip programming and non intrusive debugging

• 96-bit unique key for each device