BlocNotes

Notepad of a tinker, maker, hacker or whatever you call it :)

STM32L052 Development board

I usually use Arduino as default choice for all my projects thanks to all libraries available, in specifics cases I switch to STM32 to get power computing power or peripherals the ATMega328 is not able to provide.
More and more projects need ST's micro-controllers so it is time to switch to more modern µC: I recently designed a new all-around board based on STM32L0, but all STM32 with the same package should work.

Board picture

Requirements

  • Breakout all I/Os
  • WS2812 RGB led: blinky things, you know !
  • 3.3V LDO regulator
  • Easy way to select Vin or Vusb (jumper)
  • Easy way to select BOOT0 (jumper)
  • USB connector and ESD protection
  • 200 to 300 mA mosfet in order to control a more power or other voltages
  • Reset button
  • Breadboard friendly
  • "FDTI" pinout connector for serial communications, and to try ST serial bootloader
  • All components on one side, so the board can be easily reflowed with hotplate

Caveats & improvements

The batch of WS2812b I have works well @3.3V, but it might not be the case for all LED as datasheet specifies Vin=[3.5;5V].
Also, old habits die hard, I tried to put to much things in a small board, so routing can be improved, and for next revisions I will change :

  • Smaller ST-Link header (1.27 vs pogopin ?)
  • FTDI connector can be dropped:
  • Thanks to ST-Link and cheap Nucleo the serial bootloader is not used for development, I think that it might be useful in production but in dev. having access to the debugger is really better.
  • Serial communications can be handled by the STM's USB, if included in selected µC. If not, just wire the serial pins.
  • As ST-Link is always used to program the board, BOOT0 can be tied to ground or only be a solder bridge.
  • I will not switch from Vin to Vusb really often, so this jumper can be converted to a solder bridge too.
  • R6 and R7 can be taken away from each other, to ease hand soldering.
  • Mounting holes are not usable with screws, only push fit pins.
  • Design files and example codes can be found on Github
  • Can be ordered from OSH Park