These are cheap development Arm Cortex-M3 boards with 64KB flash and 20KB ram.

The firmware that ships on these devices blinks the LED on PC13 and sends a time string on the UART at 9600 baud.

These boards can be programmed using SWD or with the STM serial boot loader in ROM. Both types of programmer are inexpensive but the latter more versatile if somewhat slower in operation.

   B12        MICRO USB         GND
   B13                          GND
   B14                          3V3
   B15   RESET    GND    GND  RESET 
   A8    BUTTON  *BOOT1 *BOOT0  B11
TX A9             3V3    3V3    B10
RX A10                           B1
   A11                           B0
   A12                           A7
   A15                           A6
   B3       STM32F103C8T6        A5
   B4                            A4
   B5                            A3
   B6                            A2
   B7              8M            A1
   B8           32768            A0
   B9                           C15
   5V       PC13     POWER      C14
   GND      LED      LED        C13
   3V3           SWD           VBAT
          3V3 DIO  DCLK GND
              PA13 PA14

*100K IN SERIES

Power is supplied on the USB socket which feeds a 3V3 LDO regulator.

It is possible to power the device with 3V3 on the 3V3 pin or 5V on the 5V pin (to feed the LDO) if USB is disconnected.

This demo depends on OpenCM3 and this must be installed first.

Install the STLink programmer to program using a SWD interface found, for example, on the STM32 F4 discovery (see top picture).

Fetch blinky, install and run.

hg clone http://hg.kewl.org/pub/miniblink-vcc-gnd
cd miniblink-vcc-gnd
make
make st-flash
 FLASH  miniblink.bin
 INFO src/stlink-common.c: Loading device parameters....
 INFO src/stlink-common.c: Device connected is: F1 Medium-density device, id 0x20036410
 INFO src/stlink-common.c: SRAM size: 0x5000 bytes (20 KiB), Flash: 0x10000 bytes (64 KiB) in pages of 1024 bytes
 INFO src/stlink-common.c: Attempting to write 664 (0x298) bytes to stm32 address: 134217728 (0x8000000)
Flash page at addr: 0x08000000 erased
 INFO src/stlink-common.c: Finished erasing 1 pages of 1024 (0x400) bytes 
 INFO src/stlink-common.c: Starting Flash write for VL/F0/F3 core id
 INFO src/stlink-common.c: Successfully loaded flash loader in sram
  0/0 pages written
 INFO src/stlink-common.c: Starting verification of write complete
 INFO src/stlink-common.c: Flash written and verified! jolly good!

It is also possible to use STM32Flash, however, this cannot function with USB connected since if the chip detects BOOT0 raised along with a USB cable on reset, it enters DFU mode.

To use STM32Flash, disconnect USB and power with 3V3 on the 3V3 pin using a 3V3 USB serial adapter. You must cross over serial Rx and Tx and place the jumpers with BOOT1 at 0 and BOOT0 at 1 (see bottom picture).

Probe the chip with STM32Flash. This may take a few attempts to synchronise.

stm32flash /dev/ttyUSB0
stm32flash 0.4

http://stm32flash.googlecode.com/

Interface serial_posix: 57600 8E1
Version      : 0x22
Option 1     : 0x00
Option 2     : 0x00
Device ID    : 0x0410 (Medium-density)
- RAM        : 20KiB  (512b reserved by bootloader)
- Flash      : 128KiB (sector size: 4x1024)
- Option RAM : 16b
- System RAM : 2KiB

The flash size reported by STM32Flash would appear to be hard-coded and in this case wrong, ignore that.

Now fetch blinky, install and run.

hg clone http://hg.kewl.org/pub/miniblink-vcc-gnd
cd miniblink-vcc-gnd
make
make stm32flash
 FLASH  miniblink.bin
stm32flash -w miniblink.bin -b 57600 -v -g 0 /dev/ttyUSB0
stm32flash 0.4

http://stm32flash.googlecode.com/

Using Parser : Raw BINARY
Interface serial_posix: 57600 8E1
Version      : 0x22
Option 1     : 0x00
Option 2     : 0x00
Device ID    : 0x0410 (Medium-density)
- RAM        : 20KiB  (512b reserved by bootloader)
- Flash      : 128KiB (sector size: 4x1024)
- Option RAM : 16b
- System RAM : 2KiB
Write to memory
Erasing memory
Wrote and verified address 0x080004b0 (100.00%) Done.

Starting execution at address 0x08000000... done.

To reprogram the device, press reset on the board. Remember not to connect USB simultaneously.

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