by 0xCB

Image of Board

The 0xCB Helios is our Elite-C compatible MicroController, based on the high-performance and affordable RP2040.

It’s a drop-in replacement for legacy ProMicro boards.

Technical details

  • Powerful RP2040 32-bit Cortex M0+ dual core running at 133 MHz and 264kB SRAM.
  • 16MB/128Mb QSPI FLASH chip for storing files and code
  • Only 3.16 mm thick thanks to a mid-mounted USB-C port
  • 3.3V 500mA LDO, PTC fuse and ESD protection chip
  • Elite-C, Pro Micro, SparkFun Pro Micro RP2040, and nice!Nano compatible pinout (follows the BastardKb standard)
  • 8 extra I/O pins: (GP12-GP16) added along the bottom edge, (GP10-GP11) at the top and a 5V level shifted pin to drive RGB LEDs for example (GP25)
  • 25 available digital pins for a maximum of 13x12 = 156 switches (using a standard matrix)
  • Default off red power LED (selectable via a jumper on the left side)
  • blue user LED on pin GP17
  • 4 pins configurable as analog inputs
  • USB D+/D- broken out for use with an external USB socket/daughterboard
  • USB VBUS detection on GPIO19 for split keyboard side detection
  • UF2 bootloader for drag & drop programming via your file manager
  • easy to use and backward compatible Single button boot and reset circuit push to reset and hold >500ms to enter bootloader (legacy boards with reset buttons will continue to work!)
  • RAW / VBUS output, for powering RGB LEDs or other 5 V devices. The jumper on top lets you skip over the 500 mA fuse and Schottky diode, for up to 3A from USB ports.
  • USB-C connector lets you access built-in ROM USB bootloader and serial port debugging



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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.