Open hardware electronics

There are a good number of companies and enthusiasts who produce open hardware designs.

These notably include Adafruit, Sparkfun, Olimex MLab Zio Plus a variety of individuals on Tindie , OSHWlab or Kitspace

Using electronics typically involves connecting an MCU to various sensors, peripherals or actuators. There are a few standards that try to combine these in an abstract way. Notably Qwiic or Grove for I2C and UEXT which adds SPI. There is also Mikroe Click or Breakout garden but these boards tend not to be open hardware. The problem of incompatible I2C standards is documented here

There are also the ‘stacking’ standards, notably Featherwing, PyEC, M5stack , the RPI 40 pin header or Beagle Bone.

I’ve developed boards in both the M5stack and Feather footprints, but the Feather is small and has limited pins and the M5stack header is hard to source. I explored for a while whether the stacking 40pin header used by the Pi can be useful in a microcontroller context. There have been some recent attempts to do this with the RPI2040-based M10 or ESP32-based EsPiFF (which additionally reuses the Pi form factor). In both these cases you are tied to the MCU offered by the designer with no flexibility to change.


Microcontroller concept, based on Sparkfun MicroMod system, expanded to allow for 30mm boards Hopefully additionally including the fully open hardware Core-V

(Optional Ethernet, Capable of running Meshtastic with UEXT LoRa)

Featherwing concept

(Would need to be top board to stack, Feather header, 2 Pi hat pinout)

UEXT/ Mikroe/ Grove/ Qwiic concept

(Directional distance sensors for robotics. Adaptor for Qwiic)

Micromod Function cards (Ethernet, GPS, RTK)

Slightly off the Microprocessor topic, A board that takes a Raspberry PI CM4 or compatible processor

Robotics cape exists


Motor/ Servo cape (I2C) exists This would fit on a Zumo or similar robot

Grove exists


 Mikroe Click exists

Beagle Proto exists

Beagle > RPI header exists (But is closed hardware)

Plus many more Beaglebone Capes

Accessories & Sensors

UEXT Ethernet


UEXT Zigbee


UEXT screen




MicroMod LoRa

MicroMod RTK

Mikroe RTK

Grove/ Qwiic Featherwing

UEXT > Breakout garden

VL53L5CX Breakout garden


All the Featherwings






Older abandoned idea – using the Pi header

two of the 40pin Pi header. One would use the standard Pi GPIO With the other optimised for Microcontrollers.

Pi Square carrier 71mm x 71m?

M2 Processor slot

Feather pin header


Feather / UEXT daughter board

Feather wings



Zumo robot daughter board

A board that will fit on the Zumo chassis

With components compatible with the Smartcar Shield software

MicroMod function board

 MicroMod function daughter board

Mikroe Click board

2x Mikroe click

Battery Board

3x 18650

USBC charge


CM4 board

A board that takes a Raspberry PI CM4 or compatible processor

Proto board

Prototyping space