Update: CHUBSIE552(G) v1.0 pinswap

What is CHUSBIE?

CHUSBIE is a range of development boards for the CH55x range for Microcontrollers from WCH, which keeps low cost and useability as its guiding principles.

What is the CHUSBIE552?

CHUSBIE552 is the development board specifically for CH552T or the CH552G MCUs both versions are available as the CHUSBIE552(T) and the CHUSBIE552(G).

What is the difference between the CHUSBIE552(T) and the CHUSBIE552(G)?

There is very little difference between the two versions of the CHUSBIE552. The CHUSBIE552(G) has 4 less IO pins to the CHUSBIE552(T) which also means an external crystal cannot be used on this board this also makes the CHUSBIE552(G) slightly lower in price.
To see the differences please consult the pinout diagram below.

Why Am I making it?

I feel that making adding USB interfaces to device should not be hard or costly. USB has been around for many years now but there still seems to be a barrier to entry in terms of cost or complexity. The CHUSBIE552 is both compact and low cost which gives the ability to permanently embed it into a project. I have tried to include items that I feel help keep th (TTB) Time To Blink low.   

CHUSBIE552 pinout

Hardware Specifics 

RX LED is on P3.0
TX LED is attached to P3.1
These can be used to indicate UART0 transactions or can be used for PWM dimming.
The CH552 can be reset by pushing the reset button pulling the reset pin HIGH.
CHUSBIE can be powered by USB or Via the VCC and GND pins.

Note: if you supply voltage is lower than 3.6V a 3.3V supply will need to be attached to the 3V3 pin 

To enter USB bootloader mode

  • Unplug USB cable or cut power to device (if powered from a separate supply) Please note the CH552 needs 5V power to be able to program flash.  
  • Hold down BOOTL button and reinsert usb cable or repower device
  • Quickly let go of BOOTL button.


The main supported tool chain for this device is SDCC please follow my tutorial with on getting started with the CH55x: 

Support for the Arduino IDE coming soon.

Update: CHUBSIE552(G) v1.0 pinswap

It has bee discovered there is a minor bug in the CHUSBIE552(G) v1.0 that P3.0 and P3.1 are swapped over. This only affects this particular version of the board, and puts no limitations on functionality.


  1. Any idea to which pin of the CH552G the BOOTL is connected to?

  2. Do you know if it will handle I2C, and which pins I should be using for SCL and SDA ? SPI is not an option in my application :/