The Cricket CH559 is a small development board utilizing the form factor of the popular Raspberry Pi Zero line of single board computers. In this way the board already has a wide range of enclosures and expansion cards ready to experiment with.

The CH559 is a low cost USB microcontroller featuring an enhanced 8051 core, 2 USB hosts (or 1 host/1 device), SPI UART, ADC, etc.

The board itself is powered via Micro USB, or alternatively via the GPIO header. An LDO supplies 3.3V to the appropriate 3.3V supply pins on the GPIO interface, and the CH559 does the rest of the work, programming takes place over the Micro USB port after having jumped the pins marked "PROG" on the silkscreen.

A preliminary Arduino Core is available at https://github.com/DeqingSun/ch55xduino

I have flashed all boards with a simple Blink example, which also gives them a tiny bootloader that exposes a CDC on the USB device port. To start programming using the core above, just install the above Arduino core, pick the board's UART, and hit upload.

• These "Beta" boards are second revision PCB, they are functional, with the same 40-pin header layout, however the rest of the board is not finalized (labeling, placement of secondary headers, etc)
• The "Accessory" boards are final revision PCBs configured to operate as an add-on for devices like the Cricket-ONE or other Pi-compatible header boards to provide anything from extra USB ports to data logging or a USB debug terminal.
• The "Standalone" boards are final revision PCBs configured to be the primary controller in your project, and are able to drive other accessory boards or a broad variety of Raspberry Pi compatible HATS.

All boards come as imaged, add the 40-pin header or socket of your choice and enjoy!