{"product_id":"adafruit-usb-host-bff-for-qt-py-or-xiao-with-max3421e","title":"Adafruit USB Host BFF for QT Py or Xiao with MAX3421E","description":"\u003cp\u003e\u003ca rel=\"noopener\" href=\"https:\/\/shop.pimoroni.com\/search?q=qt%20py\" target=\"_blank\"\u003eIs your QT Py all alone\u003c\/a\u003e, lacking a friend to travel the wide world with? When you were a kid, you may have learned about the \"buddy\" system. Well, this product is kind of like that! It is a board that will watch your QT Py's back and add a USB Host port.\u003c\/p\u003e\n\u003cp\u003eThat means that your tiny microcontroller project can have a keyboard, mouse, or disk drive plugged into it, opening up a huge ecosystem of common off-the-shelf devices that you can now integrate. The\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003eAdafruit USB Host BFF\u003cspan\u003e \u003c\/span\u003e\u003c\/strong\u003emakes it easy to add USB Host support, especially now that\u003cspan\u003e \u003c\/span\u003e\u003ca href=\"https:\/\/github.com\/adafruit\/Adafruit_TinyUSB_Arduino\"\u003eTinyUSB supports it in the Arduino library\u003c\/a\u003e\u003cspan\u003e \u003c\/span\u003eas a 'native' interface for host support. \u003c\/p\u003e\n\u003cp\u003eThis BFF uses the MAX3421E - a tried and true USB Host chip. It uses SPI plus an IRQ pin to send data to just about any USB device. Note that because the chip is older and you're limited to the SPI port speed, you won't get blazing 480Mbps high-speed data transfer. But for basic HID interfacing or even reading\/writing to a Mass Storage device, it does work quite well. There's a famous\u003cspan\u003e \u003c\/span\u003e\u003ca href=\"https:\/\/github.com\/felis\/USB_Host_Shield_2.0\"\u003eUSB Host Library that can be used\u003c\/a\u003e, and its specialty is AVR support, but it also seems to support nRF52 and ESP32.\u003c\/p\u003e\n\u003cp\u003eWe personally recommend using the\u003cspan\u003e \u003c\/span\u003e\u003ca href=\"https:\/\/github.com\/adafruit\/Adafruit_TinyUSB_Arduino\"\u003eTinyUSB Arduino library\u003c\/a\u003e\u003cspan\u003e \u003c\/span\u003e- however, the trade-off is that the chip must have TinyUSB support already, which means it's great for\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003eRP2040, ESP32-S2 or S3, nRF52840, SAMD21\/51 chips\u003c\/strong\u003e. Make sure your desired QT Py mainboard is supported between the two libraries before purchasing! \u003c\/p\u003e\n\u003cp\u003eTo keep the BFF very compact, we use a micro-B USB \"OTG\" connector - a full sized USB Type A wouldn't fit! You'll need to use\u003cspan\u003e \u003c\/span\u003e\u003ca rel=\"noopener\" href=\"\/products\/usb-to-microusb-otg-converter-shim\" target=\"_blank\"\u003ea basic OTG adapter (such as those sold for use with the Pi Zero) to convert to type A\u003c\/a\u003e. Unlike our\u003cspan\u003e \u003c\/span\u003e\u003ca rel=\"noopener\" href=\"\/products\/adafruit-usb-host-featherwing-with-max3421e\" target=\"_blank\"\u003eUSB Host 'Wing\u003c\/a\u003e\u003cspan\u003e \u003c\/span\u003ewe don't include a 5V power booster, so you will need to power the QT Py + BFF over USB or in some other way provide 5V on the 5V power line. However, to make it easier to power-cycle the peripheral, we have wired up a P-FET for switching the 5V host power on and off, you can either short the pin to A0 or you can use the MAX3421E's GPIO pin.\u003c\/p\u003e\n\u003cp\u003eWe include some header that you can solder to your QT Py.\u003cspan\u003e \u003c\/span\u003e\u003ca rel=\"noopener\" href=\"\/products\/short-feather-headers-kit-12-pin-and-16-pin-female-header-set\" target=\"_blank\"\u003eYou can also pick up a short female header kit to make it removable but compact\u003c\/a\u003e; you'll need to trim the headers to 7 pins long.\u003c\/p\u003e\n\u003cp\u003eRemember, you need driver support for the MAX3421E (see above for chips that are known to work). Unless you're using a generic mouse, keyboard, CDC serial, or USB mass storage device, you will also need a USB driver that knows how to talk to the device—and writing a driver is non-trivial.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eQT Py or Xiao is not included!\u003c\/strong\u003e\u003c\/p\u003e\n\u003ch2\u003eTechnical Details\u003c\/h2\u003e\n\u003cp\u003eProduct Dimensions: 21.5mm x 17.8mm x 4.0mm \/ 0.8\" x 0.7\" x 0.2\"\u003c\/p\u003e\n\u003cp\u003eProduct Weight: 1.5g \/ 0.1oz\u003c\/p\u003e\n\u003cp\u003e\u003cimg height=\"80\" width=\"145\" alt=\"RoHS 2 2011 65 EU Compliant\" src=\"https:\/\/www.adafruit.com\/includes\/templates\/shop2019\/images\/RoHS2_2011_65_EU.svg\"\u003e \u003cimg height=\"80\" width=\"145\" alt=\"RoHS 2 2015 863 EU Compliant\" src=\"https:\/\/www.adafruit.com\/includes\/templates\/shop2019\/images\/RoHS2_2015_863_EU.svg\"\u003e\u003c\/p\u003e","brand":"Adafruit","offers":[{"title":"Default Title","offer_id":56500164591989,"sku":"ADA5956","price":12.45,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0389\/1025\/files\/5956-00.jpg?v=1766148584","url":"https:\/\/wholesale.pimoroni.com\/products\/adafruit-usb-host-bff-for-qt-py-or-xiao-with-max3421e","provider":"Pimoroni Wholesale","version":"1.0","type":"link"}