A while back I purchased some generic STM32F103C8T6 development boards on eBay for about $4 each. I initially had some limited success programming them using the GCC ARM Embedded (eabi) toolchain and a generic STM32 loader program. Since then I've discovered a project to get them working with the Arduino 1.5+ toolchain.
There's a lot of different information about the various STM32 boards out there. I'm documenting my notes here mostly for my own sanity since I don't play with these boards often. Maybe you'll find it useful too.
Arduino hardware library for these boards:
"Support" forum: http://www.stm32duino.com/
The USB port
The generic boards do not have a meaningful USB bootloader. The USB port is only useful for power. (TODO: Flash the "Maple Mini" bootloader onto them for future ease of use?)
Arduino Board Selection & options
Tools -> Board -> Generic STM32F103C
Tools -> Variant -> "STM32F103C8 (20k RAM. 64k Flash)"
Tools -> Upload method -> "Serial"
FTDI / Serial connection
Connect 3.3V FTDI USB -> Serial programmer as follows:
- STM32 UART0 TX pin A9 -> FTDI RX
- STM32 UART0 RX pin A10 -> FTDI TX
I use the GND and 3.3 pins on the 4-pin header for power, but the ones on the IO pads work fine too.
Program / Run Jumper
- Run mode: Both jumpers at "0"
- Program Mode: Jumper 0 (top) at "1"
With J0 set to "1", press "reset" just before hitting "upload" in Arduino to flash firmware. Program will run immediately after flashing, but won't run after power-cycle until you set Jumper 0 back to "0". (??)
I have no idea what the bottom jumper is for.
PC13 LED seems to be wired from +3.3V to the PC13 pin. So setting the pin low lights the LED, and setting it high extinguishes it.
That's it! With any luck, after loading the above library and following these notes you can push Arduino sketches to your super-cheap, 72MHz STM32 ARM board.