The Adafruit CH552 QT Py is a compact development board built around the WCH CH552, an enhanced 8-bit 8051 microcontroller. Running at 16 MHz with native USB device support, it packs a surprising amount of functionality into the tiny QT Py form factor with STEMMA QT / Qwiic I2C connectivity.

The CH552 features 16 KB program flash, 256 bytes of internal RAM, and 1 KB of xRAM with DMA support. Its native USB controller enables it to act as a CDC serial device or HID keyboard/mouse without additional hardware. The board is Seeed Xiao compatible in size and pinout, with castellated pads for surface-mount soldering.

Key Features

• CH552 8051 Core – Enhanced 8-bit microcontroller at 16 MHz, 3.3V logic
• 16 KB Flash / 256 B RAM / 1 KB xRAM – xRAM supports DMA
• Native USB Device – Full-speed USB for CDC serial, HID keyboard/mouse
• 10 GPIO Pins – Including 4× 8-bit ADC, 3× PWM, hardware UART, hardware SPI, I2C
• 4× Capacitive Touch – On A0–A3 pins, no additional components needed
• RGB NeoPixel LED – Built-in programmable LED
• STEMMA QT / Qwiic – Plug-and-play I2C connector for sensors and accessories
• USB-C Connector – For programming and power
• Reset + Bootloader Buttons – Easy access to USB ROM bootloader mode
• 3.3V Regulator – 600 mA peak output
• Castellated Pads – Seeed Xiao compatible for surface-mount soldering

Ideal For

• Learning and experimenting with 8051 architecture
• Custom USB device projects (HID, CDC serial)
• Ultra-low-cost embedded USB applications
• Compact projects requiring a minimal microcontroller

Package Contents

• 1× Adafruit CH552 QT Py development board