Adafruit USB Host BFF for QT Py or Xiao with MAX3421E
20 units available with a short lead time.
The Adafruit USB Host BFF adds a USB Host port to your QT Py or Xiao microcontroller, letting you connect keyboards, mice, USB drives, and other standard USB peripherals to your tiny project. It uses the MAX3421E USB Host chip, communicating over SPI with an IRQ pin.
With driver support through the TinyUSB Arduino library (recommended for RP2040, ESP32-S2/S3, nRF52840, SAMD21/51) or the USB Host Shield 2.0 library (AVR, nRF52, ESP32), you can integrate a wide range of USB devices into your projects.
Key Features
- MAX3421E USB Host Chip – Proven SPI-based USB Host controller
- Micro-B OTG Connector – Compact USB host port (use an OTG adapter for Type-A devices)
- 5V Power Switching – P-FET for toggling host power on/off via A0 pin or MAX3421E GPIO
- BFF Form Factor – Plugs directly onto the back of any QT Py or Xiao board
- SPI Interface – Uses SPI plus IRQ pin for communication
- HID & Mass Storage – Works with keyboards, mice, game controllers, and USB drives
Compatible Chips
- TinyUSB Library – RP2040, ESP32-S2, ESP32-S3, nRF52840, SAMD21, SAMD51
- USB Host Shield 2.0 Library – AVR, nRF52, ESP32
Ideal For
- Adding keyboard or mouse input to QT Py/Xiao projects
- USB mass storage reading and writing
- HID device integration in compact form factors
- USB peripheral interfacing for IoT and embedded projects
Package Contents
- 1× Adafruit USB Host BFF with MAX3421E
- 1× Header strip for soldering
Note: QT Py or Xiao board not included. A Micro-B OTG adapter is required to connect standard Type-A USB devices. No built-in 5V boost — power must be supplied via USB or external 5V on the power line.
Important: Verify that your QT Py or Xiao board is supported by either the TinyUSB or USB Host Shield 2.0 library before purchasing. For non-standard USB devices, a custom USB driver is required.
Resources
The Adafruit USB Host BFF for QT Py or Xiao with MAX3421E appears in the following collections:
SKU AF-5956
by Adafruit
