by MechWild

Image of Board

The PillBug is a BLE enabled development board powered by the nRF52840 that is designed to be a drop in replacement for the stm32f401/stm32f411 blackpill development board. This board was designed for compatibility with blackpill driven keyboards and will work as a simple replacement in most cases. The PillBug features 3.7V Li-Ion battery charger, a software controlled hardware cutoff for powering peripherals, a controllable status LED, and compatibility with blackpill’s pinouts for I2C/SPI/UART.

Technical details

  • BLE (Bluetooth Low Energy) capable
  • nRF52840 powered with 1MB Flash memory and 256KB RAM
  • Preloaded Adafruit nRF52 Bootloader utlizing UF2 and DFU flashing options
  • Software controlled blue status LED that can be configured by application
  • Hardware controlled charging red status LED
  • 3.3V GPIO logic and power provided through VCC pins
  • Software controlled MOSFET to disable providing power through the power pins to external peripherals
  • 30 Total GPIO pins in an easy to use and breadboard friendly layout
  • RTC (real-time clock) capabilities provided through use of 32.768kHz oscillator (necessary for BlE)

Learn More



Have some info to add for this board? Edit the source for this page here.

Absolute Newest

Every time we commit new code to CircuitPython we automatically build binaries for each board and language. The binaries are stored on Amazon S3, organized by board, and then by language. Try them if you want the absolute latest and are feeling daring or want to see if a problem has been fixed.

Past Releases

All previous releases are listed on GitHub, with release notes, and are available for download from Amazon S3. They are handy for testing, but otherwise we recommend using the latest stable release. Some older GitHub release pages include the same binaries for downloading. But we have discontinued including binaries as assets on newer release pages because of the large number of files for each release.


Update UF2 Bootloader

Latest version: 0.7.0

The bootloader allows you to load CircuitPython, MakeCode, and Arduino programs. The bootloader is not CircuitPython. You can check the current version of your bootloader by looking in the INFO_UF2.TXT file when the BOOT drive is visible (FEATHERBOOT, CPLAYBOOT, etc.).

It is not necessary to update your bootloader if it is working fine. Read the release notes on GitHub to see what has been changed. In general, we recommend you not update the bootloader unless you know there is a problem with it or a support person has asked you to try updating it.

Updating the bootloader on nRF52840 boards is an involved process right now. Follow the instructions in this README.

After you update, check INFO_UF2.TXT to verify that the bootloader version has been updated. Then you will need to reload CircuitPython.