Quick Start Guide

General information

Miao is a Xiao compatible microntroller developed by kilipan. It uses a ch552t chip, which is very handy and cost efficient, including:

  • Built-in 16KB Code Flash, 1KB XRAM and internal 256B iRAM
  • Built-in USB controller and USB transceiver
  • 2 full-duplex UARTs
  • SPI
  • 8-bit ADC
  • Built in 24Mhz clock

For the ch552t you write firmware using FAK by semickolon. FAK uses nickel to write configurations which makes things way simpler and less error prone compared to QMK.

Xiao compatability

Miao is Pin compatible to the Xiao, there are even additional pins at the top. Underneath you can find 2 pads to reset - just like the xiao.


For flashing you use wchisp and to build the firmware (and also flash) you can follow the getting started guide for FAK.

If you have troubles flashing the firmware as a regular user on Linux, you might need an additional udev rule to get access to the bootloader:

  1. Create a file named 50-wchisp.rules in the folder /etc/udev/rules.d/.
  2. Write the following content in that file:
# file: /etc/udev/rules.d/50-wchisp.rules
# WCH ISP bootloader
SUBSYSTEMS=="usb", ATTRS{idVendor}=="4348", ATTRS{idProduct}=="55e0", GROUP="uucp", MODE="0666"
  1. Add yourself to the group uucp.
  2. Log out as a user and log back in. This is necessary to enable the group and reload the udev rules.

ESD protection

To avoid accidentally shocking your Miao while plugging it in, there’s an onboard ESD protection circuit to ensure longevity!

Split capability

FAK handles the halves independently which makes configuring them very easy.


There are two solder jumpers onboard. They configure the bus output and the LED function - please consult the Pinout for help.


You can choose between UART and SPI mode for the bottom right pin.


You can choose between a power LED and a user LED. The user LED is adressed by pin 3.3.