What is it?

It's a small breakout board for the ARM Cortex-M0 STM32F030F4P6 chip. These very cute chips are hand-solderable but still very small, and have a built-in UART bootloader in ROM. They have 16kB of flash and 4kB of SRAM. The usual capabilities (timers, I2C, SPI) are of course present as well. For a detailed list of capabilities, see the datasheet.

The board is made to be analogue-friendly: the analogue voltage source (VDDA) is connected to the main voltage regulator output through a ferrite bead, and there's an extra 1uF capacitor on VDDA as well.

This board itself breaks out all the MCU's pins on the longer sides; UART pins on one of shorter sides (there are 4 pins soldered to these) and the SWD debug pins on the other shorter side, for an easy debugging access. Furthermore there is one onboard (yellow) LED, and apart from the RESET button there is also a button hooked to the BOOT0 pin.

This means that to program the chip simply hold the BOOT0 while pressing the RESET (or powering up the chip), and it enters the UART bootloader. You can then upload the firmware via the UART interface (usually using an USB-to-serial breakout). This is a hardware feature, so it always works, even if the actual firmware doesn't cooperate.

The boards have been hand-soldered by me. The design is open:

• EAGLE sources
• schematic
• PCB on OSH Park (should you prefer to make one yourself)
• a bit longer dedicated webpage

Why did you make it?

I wanted to play with the STM32F030 chips and I like making small breakouts ;)

Practicalities

The boards available now are black, 1.6mm thick, ENIG (i.e. gold pads). Please note that I'm soldering these by hand, so there usually are some tiny visual imperfections in soldering. Also some of the boards are soldered with lead-free solder - the soldering there looks less "shiny". However they are fully functional (tested), shipping with a 'serial echo plus blink' firmware.