Adafruit USB Host BFF for QT Py or Xiao with MAX3421E

Is your QT Py missing a companion to explore the tech universe? The Adafruit USB Host BFF adds a USB Host port, allowing your tiny microcontroller project to connect to keyboards, mice, or disk drives. This board opens the door to a vast array of common off-the-shelf devices, enhancing your project's capabilities.

This BFF utilizes the reliable MAX3421E USB Host chip, sending data via SPI and an IRQ pin. While high-speed data transfer isn't its forte, it meets the demands for basic HID interfacing or mass storage read/write tasks. A renowned USB Host Library specializing in AVR support extends its reach to nRF52 and ESP32, while the TinyUSB Arduino library connects it to RP2040, ESP32-S2 or S3, nRF52840, SAMD21/51 chips.

Designed for compactness, it features a micro-B USB "OTG" connector, requiring a basic OTG adapter for conversion to Type A. Note the absence of a 5V power booster, necessitating USB power for QT Py + BFF. With a P-FET wired for power cycling peripherals and headers for QT Py soldering, flexibility is ensured.

Driver support for the MAX3421E is crucial. While generic devices like mice, keyboards, or USB mass storage are easily compatible, custom USB device drivers demand expertise. QT Py or Xiao is not included, ensuring freedom of choice for your project pairings.