Available with a lead time
Expect dispatch between May 17 and May 20
Is your QT Py all alone, 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.
That 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 Adafruit USB Host BFF makes it easy to add USB Host support, especially now that TinyUSB supports it in the Arduino library as a 'native' interface for host support.
This 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 USB Host Library that can be used, and its specialty is AVR support, but it also seems to support nRF52 and ESP32.
Adafruit personally recommend using the TinyUSB Arduino library - however, the trade-off is that the chip must have TinyUSB support already, which means it's great for RP2040, ESP32-S2 or S3, nRF52840, SAMD21/51 chips. Make sure your desired QT Py mainboard is supported between the two libraries before purchasing!
To keep the BFF very compact, Adafruit use a micro-B USB "OTG" connector - a full sized USB Type A wouldn't fit! You'll need to use a basic OTG adapter (such as those sold for use with the Pi Zero) to convert to type A. Unlike Adafruit's USB Host 'Wing Adafruit 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, Adafruit 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.
Adafruit include some header that you can solder to your QT Py. You can also pick up an Itsy Bitsy short female header kit to make it removable but compact; you'll need to trim the headers to 7 pins long.
Remember, 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.
QT Py or Xiao is not included!
Product Dimensions: 21.5mm x 17.8mm x 4.0mm / 0.8" x 0.7" x 0.2"
Product Weight: 1.5g / 0.1oz
Exact shipping can be calculated on the view cart page (no login required).
Products that weigh more than 0.5 KG may cost more than what's shown (for example, test equipment, machines, >500mL liquids, etc).
We deliver Australia-wide with these options (depends on the final destination - you can get a quote on the view cart page):
Non-metro addresses in WA, NT, SA & TAS can take 2+ days in addition to the above information.
Some batteries (such as LiPo) can't be shipped by Air. During checkout, Express Post and International Methods will not be an option if you have that type of battery in your shopping cart.
International Orders - the following rates are for New Zealand and will vary for other countries:
If you order lots of gear, the postage amount will increase based on the weight of your order.
Our physical address (here's a PDF which includes other key business details):
Unit 18, 132 Garden Grove Parade
Adamstown
NSW, 2289
Australia
Take a look at our customer service page if you have other questions such as "do we do purchase orders" (yes!) or "are prices GST inclusive" (yes they are!). We're here to help - get in touch with us to talk shop.
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