# Adafruit USB Host FeatherWing with MAX3421E ## Overview ![](https://cdn-learn.adafruit.com/assets/assets/000/126/617/medium800/hacks_5858-08.jpg?1702515296) Lots of microcontrollers these days have USB ports on them, to program or debug, act like a keyboard or disk drive, or simply send data between a computer and your firmware. But did you know that you can also add a USB Host port? That means that your microcontroller project can have a keyboard or mouse or disk drive plugged into it - which opens up a huge ecosystem of common off-the-shelf devices that you can now integrate. The **Adafruit USB Host FeatherWing** makes it easy to add USB Host support, especially now that [TinyUSB supports it in the Arduino library](https://github.com/adafruit/Adafruit_TinyUSB_Arduino) as a 'native' interface for host support. ![](https://cdn-learn.adafruit.com/assets/assets/000/126/618/medium800/hacks_5858-07.jpg?1702515452) This 'Wing 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're not going to 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](https://github.com/felis/USB_Host_Shield_2.0), and it's specialty is **AVR** support, but also seems to support nRF52 and ESP32. We personally recommend using the [TinyUSB Arduino library](https://github.com/adafruit/Adafruit_TinyUSB_Arduino) - however the trade-off is that the chip must have TinyUSB support already which means it's great for **RP2040, ESP32 or S2 or S3, nRF52840, SAMD21/51** chips. Between the two libraries, just make sure your desired Feather mainboard is supported before purchasing! ![](https://cdn-learn.adafruit.com/assets/assets/000/126/619/medium800/hacks_5858-02_%281%29.jpg?1702515519) Next to the MAX3421E we have a 5V 1A booster with 500mA fuse, which can provide a nice clean 5V from the USB or Battery power supply. An enable pin is available to power cycle when desired. ![](https://cdn-learn.adafruit.com/assets/assets/000/126/620/medium800/hacks_5858-03.jpg?1702515575) It comes as an assembled 'Wing with some header. Solder on the header and plug into a Feather Mainboard to expand its capabilities! Don't forget, you need driver support for the MAX3421E (see above for chips that are known working) _and_ 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. # Adafruit USB Host FeatherWing with MAX3421E ## Pinouts ![](https://cdn-learn.adafruit.com/assets/assets/000/126/621/medium800/hacks_double.jpg?1702561372) ## USB-A Port On the left end of the FeatherWing is the USB type A port for connecting USB devices to. This USB-A port can be used for sending or receiving data from an attached USB device with the MAX3421E. ## MAX3421E Control Pins The MAX3421E USB Host chip on the FeatherWing uses SPI plus an IRQ pin to send data to just about any USB device. - **MOSI** - This is the SPI MOSI ( **M** icrocontroller **O** ut / **S** erial **I** n) pin. - **MISO** - This is the SPI MISO ( **M** icrocontroller **I** n **S** erial **O** ut) pin. - **SCK** - This is the **S** PI clo **ck** input pin. - **CS** - This is the **c** hip **s** elect pin. It is connected to **pin 10** on the FeatherWing. It is also broken out towards the middle of the board. - **IRQ** - This is the interrupt pin for the MAX3421E. It is connected to **pin 9** on the FeatherWing and is broken out towards the middle of the board. ## GPX Pin - **GPX** - Towards the center of the FeatherWing is the general purpose multiplexed push-pull output pin for the MAX3421E. This is for advanced users. The internal MAX3421E signal that appears on GPX is programmable by writing to the GPXB and GPXA bits of the PINCTL (R17) register and the SEPIRQ bit of the MODE (R27) register. GPX indicates one of five signals: 1. OPERATE: This signal goes high when the MAX3421E is able to operate after a power-up or RES reset. OPERATE is active when the RES input is high and the internal power-on-reset (POR) is not asserted. OPERATE is the default GPX output. 2. VBUS\_DET: VBUS\_DET is the VBCOMP comparator output. This allows the user to directly monitor the VBUS status. 3. BUSACT: USB BUS activity signal (active high). This signal is active whenever there is traffic on the USB bus. The BUSACT signal is set whenever a SYNC field is detected. BUSACT goes low during bus reset or after 32-bit times of J-state. 4. INIRQ: When the SEPIRQ bit of the MODE (R27) register is set high, the BUSACT signal is removed from the INT output and GPX is used as an IRQ output pin dedicated to GPIN interrupts if GPX[B:A] = 10. In this mode, GPIN interrupts appear only on the GPX pin, and do not appear on the INT output pin. 5. SOF: A square wave with a positive edge that indicates the USB start-of-frame. ## 5V Enable Pin and Jumper - **5V** - Towards the middle of the FeatherWing is a pin labeled **5V**. This is the **5V enable** for the 5V 1A booster. If you tie this pin to ground, it can disable 5V power to the USB-A port, effectively turning off your connected USB device. - **5V Enable Jumper** - On the back of the FeatherWing is an open jumper. If you solder this jumper closed you will connect the **5V enable** pin to **GPOUT0** (general purpose output 0) on the MAX3421E. This output is controllable over SPI, which means you can then enable or disable 5V to the USB-A port in software. ## 5V LED - **5V LED** - Towards the right end of the FeatherWing is a green LED labeled 5V on the FeatherWing silk. It indicates whether the 5V power from the 5V 1A booster is enabled. ## Reset Button  - **RST** - The reset button, located in the top left corner on the FeatherWing, is connected to the reset pin. # Adafruit USB Host FeatherWing with MAX3421E ## CircuitPython It's easy to use the **USB Host FeatherWing** with CircuitPython and the [max3421e](https://docs.circuitpython.org/en/latest/shared-bindings/max3421e/index.html) core module. This module allows you to easily write Python code that lets you utilize the MAX3421E USB Host chip. CircuitPython support is available for many Adafruit Feather Espressif boards, the [Adafruit Feather RP2040 DVI](https://circuitpython.org/board/adafruit_feather_rp2040_dvi/), and many other boards. See [the Module Support Matrix](https://docs.circuitpython.org/en/latest/shared-bindings/support_matrix.html?filter=max3421e) for a complete list. ## CircuitPython Microcontroller Wiring You can use a FeatherWing Doubler to easily connect a Feather and USB Host FeatherWing. ### FeatherWing Doubler - Prototyping Add-on For All Feather Boards [FeatherWing Doubler - Prototyping Add-on For All Feather Boards](https://www.adafruit.com/product/2890) This is the **FeatherWing Doubler** - a prototyping add-on and more for all Feather boards. This is similar to our [FeatherWing Proto](https://www.adafruit.com/products/2884) except there are two! The magic of the Doubler comes when stacking a Feather and another... In Stock [Buy Now](https://www.adafruit.com/product/2890) [Related Guides to the Product](https://learn.adafruit.com/products/2890/guides) ![Double prototyping feather wing PCB with socket headers installed](https://cdn-shop.adafruit.com/640x480/2890-01.jpg) Plug a Feather and a USB Host FeatherWing into your FeatherWing Doubler. Here's an example connecting a Feather ESP32S3 to the FeatherWing. ![hacks_featherwingFritzCP_bb.jpg](https://cdn-learn.adafruit.com/assets/assets/000/132/014/medium640/hacks_featherwingFritzCP_bb.jpg?1724678755) ## CircuitPython Usage To use with CircuitPython, you need to update **code.py** with the example script. Thankfully, we can do this in one go. In the example below, click the **Download Project Bundle** button below to download the  **code.py** file in a zip file. Extract the contents of the zip file and copy the **code.py** file to your **CIRCUITPY** drive. Info: Only core modules are used for these examples. No additional libraries need to be added to the /lib folder. ![CIRCUITPY](https://adafruit.github.io/Adafruit_Learning_System_Guides/USB_Host_BFF_Examples_CircuitPython_DeviceInfo_FeatherWing.png ) ## Device Info Example Code Once everything is saved to the **CIRCUITPY** drive, [connect to the serial console](https://learn.adafruit.com/welcome-to-circuitpython/kattni-connecting-to-the-serial-console) to see the data printed out! https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/USB_Host_BFF_Examples/CircuitPython_DeviceInfo_FeatherWing/code.py First, the MAX3421E is instantiated over SPI. In the loop, a scan is performed every 5 seconds on the USB host port for a connected USB device. If a device is detected, its VID, PID, manufacturer name and product name are printed to the serial monitor. You can plug and unplug devices to experiment with this. ![](https://cdn-learn.adafruit.com/assets/assets/000/132/013/medium800/hacks_cp_serial.png?1724678486) # Adafruit USB Host FeatherWing with MAX3421E ## Python Docs # Adafruit USB Host FeatherWing with MAX3421E ## Arduino Library Install and Simple Test Warning: An issue was introduced in version 3.2.0 of the ESP32 Arduino board support package that causes [MAX3421E examples to not compile](https://github.com/adafruit/Adafruit_TinyUSB_Arduino/issues/513). To use this FeatherWing with an ESP32 board in Arduino, downgrade to a previous version of the board support package (ex. 3.1.3). Using the USB Host FeatherWing with Arduino involves connecting your FeatherWing to an Arduino-compatible Feather microcontroller that has TinyUSB support ( **ESP32, ESP32-S2 or ESP32-S3**** , nRF52840, SAMD21/51, RP2040** chips), plugging in a USB device to the USB-A port on the USB Host FeatherWing, installing the [Adafruit\_TinyUSB\_Arduino](https://github.com/adafruit/Adafruit_TinyUSB_Arduino) library, and running the provided example code. Info: ### FeatherWing Doubler - Prototyping Add-on For All Feather Boards [FeatherWing Doubler - Prototyping Add-on For All Feather Boards](https://www.adafruit.com/product/2890) This is the **FeatherWing Doubler** - a prototyping add-on and more for all Feather boards. This is similar to our [FeatherWing Proto](https://www.adafruit.com/products/2884) except there are two! The magic of the Doubler comes when stacking a Feather and another... In Stock [Buy Now](https://www.adafruit.com/product/2890) [Related Guides to the Product](https://learn.adafruit.com/products/2890/guides) ![Double prototyping feather wing PCB with socket headers installed](https://cdn-shop.adafruit.com/640x480/2890-01.jpg) ## Hardware Plug in a TinyUSB supported Feather and the USB Host FeatherWing to a FeatherWing Doubler. Then, plug a USB device into the USB-A port on the USB Host FeatherWing. The USB-A port is **only** for connecting USB devices. You cannot program the Feather with that port. ![hacks_edited_IMG_0339.jpg](https://cdn-learn.adafruit.com/assets/assets/000/126/766/medium640/hacks_edited_IMG_0339.jpg?1703019825) Warning: ## Library Installation You can install the **Adafruit\_TinyUSB\_Arduino** library using the Library Manager in the Arduino IDE. ![](https://cdn-learn.adafruit.com/assets/assets/000/126/767/medium800/hacks_Arduino_Open_Library_Manager.png?1703020121) Click the **Manage Libraries ...** menu item, search for **Adafruit\_TinyUSB** , and select the **Adafruit TinyUSB**  library: ![](https://cdn-learn.adafruit.com/assets/assets/000/126/768/medium800/hacks_lib.png?1703020282) If asked about dependencies, click "Install all". ![](https://cdn-learn.adafruit.com/assets/assets/000/126/769/medium800/hacks_depends.png?1703020313) If the "Dependencies" window does not come up, then you already have the dependencies installed. Warning: ## Device Info MAX3421E Example Navigate to the **Adafruit TinyUSB Library Examples** and select **DualRole -\> Simple -\> device\_info\_max3421e** ![](https://cdn-learn.adafruit.com/assets/assets/000/126/843/medium800/hacks_host-max3421e-device_info.png?1703668819) https://github.com/adafruit/Adafruit_TinyUSB_Arduino/blob/master/examples/DualRole/Simple/device_info_max3421e/device_info_max3421e.ino Upload the sketch to your board and open up the Serial Monitor ( **Tools -\> Serial Monitor** ) at 115200 baud. As you plug and unplug your USB device to the USB Host FeatherWing, you will see the device info print out to the Serial Monitor. ![](https://cdn-learn.adafruit.com/assets/assets/000/126/770/medium800/hacks_demoSerial.png?1703022636) # Adafruit USB Host FeatherWing with MAX3421E ## Arduino Data Logger Example Warning: An issue was introduced in version 3.2.0 of the ESP32 Arduino board support package that causes [MAX3421E examples to not compile](https://github.com/adafruit/Adafruit_TinyUSB_Arduino/issues/513). To use this FeatherWing with an ESP32 board in Arduino, downgrade to a previous version of the board support package (ex. 3.1.3). In the data logger example, you'll log data from a potentiometer connected to pin A0 on your TinyUSB supported Feather to a USB drive plugged into the USB Host FeatherWing. ### FeatherWing Tripler Mini Kit - Prototyping Add-on For Feathers [FeatherWing Tripler Mini Kit - Prototyping Add-on For Feathers](https://www.adafruit.com/product/3417) This is the **FeatherWing Tripler** - a prototyping add-on and more for all Feather boards. This is similar to our [FeatherWing Proto](https://www.adafruit.com/products/2884) except there are three! The magic of the Tripler comes when you want to connect your Feather to... In Stock [Buy Now](https://www.adafruit.com/product/3417) [Related Guides to the Product](https://learn.adafruit.com/products/3417/guides) ![Triple prototyping feather wing PCB with socket headers installed](https://cdn-shop.adafruit.com/640x480/3417-05.jpg) ### STEMMA Wired Potentiometer Breakout Board - 10K ohm Linear [STEMMA Wired Potentiometer Breakout Board - 10K ohm Linear](https://www.adafruit.com/product/4493) For the easiest way possible to measure twists, turn to this STEMMA potentiometer breakout (ha!). This plug-n-play pot comes with a JST-PH 2mm connector and a matching  [JST PH 3-Pin to Male Header Cables - 200mm](https://www.adafruit.com/product/3893), so wiring up is a cinch.... Out of Stock [Buy Now](https://www.adafruit.com/product/4493) [Related Guides to the Product](https://learn.adafruit.com/products/4493/guides) ![Video of a white hand turning the knob on a STEMMA Wired Potentiometer Breakout Board connect to a breadboard. Color changes when the knob is twisted. ](https://cdn-shop.adafruit.com/product-videos/640x480/4493-04.jpg) ### STEMMA JST PH 2mm 3-Pin to Male Header Cable - 200mm [STEMMA JST PH 2mm 3-Pin to Male Header Cable - 200mm](https://www.adafruit.com/product/3893) This cable will let you turn a JST PH 3-pin cable port into 3 individual wires with high-quality 0.1" male header plugs on the end. We're carrying these to match up with our Hallowing, for extending and connecting sensors or LEDs - and the wires are even color coded! In Stock [Buy Now](https://www.adafruit.com/product/3893) [Related Guides to the Product](https://learn.adafruit.com/products/3893/guides) ![Angled shot of STEMMA JST PH 3-Pin to Male Header Cable - 200mm.](https://cdn-shop.adafruit.com/640x480/3893-03.jpg) ## Wiring - Plug a TinyUSB supported Feather and USB Host FeatherWing into a FeatherWing Tripler - Connect a potentiometer to the FeatherWing Tripler - **Potentiometer ground** to **Feather GND** - **Potentiometer wiper** to **Feather A0** - **Potentiometer voltage** to **Feather 3.3V** - Plug a USB drive into the USB Host FeatherWing ![hacks_datalog.jpg](https://cdn-learn.adafruit.com/assets/assets/000/126/771/medium640/hacks_datalog.jpg?1703029588) ## Data Logger Example Load the example code onto your Feather after following the library installation instructions on the [Arduino Library Install page](https://learn.adafruit.com/adafruit-usb-host-featherwing-with-max3421e/arduino). Navigate to the **Adafruit TinyUSB Library Examples** and select **DualRole - MassStorage - msc\_data\_logger** ![](https://cdn-learn.adafruit.com/assets/assets/000/126/779/medium800/hacks_exampleMassStorage.png?1703032809) https://github.com/adafruit/Adafruit_TinyUSB_Arduino/blob/master/examples/DualRole/MassStorage/msc_data_logger/msc_data_logger.ino After uploading the sketch to your board, open up the Serial Monitor ( **Tools -\> Serial Monitor** ) at 115200 baud. After you plug in your USB drive to the USB Host FeatherWing, you will the files currently on the drive print out to the Serial Monitor. As you turn the potentiometer, you'll see the values alongside a timestamp print to the Serial Monitor. ![](https://cdn-learn.adafruit.com/assets/assets/000/126/772/medium800/hacks_log_1.png?1703029977) The values are saved to a file called **cpu\_temp.csv**. If you open the CSV file on your computer, you'll see the logged values. ![](https://cdn-learn.adafruit.com/assets/assets/000/126/773/medium800/hacks_log_csv.png?1703030026) # Adafruit USB Host FeatherWing with MAX3421E ## Arduino Serial Host Bridge Example In the serial host bridge example, you'll see serial messages printed out from another microcontroller plugged into your USB Host FeatherWing. Warning: ### FeatherWing Doubler - Prototyping Add-on For All Feather Boards [FeatherWing Doubler - Prototyping Add-on For All Feather Boards](https://www.adafruit.com/product/2890) This is the **FeatherWing Doubler** - a prototyping add-on and more for all Feather boards. This is similar to our [FeatherWing Proto](https://www.adafruit.com/products/2884) except there are two! The magic of the Doubler comes when stacking a Feather and another... In Stock [Buy Now](https://www.adafruit.com/product/2890) [Related Guides to the Product](https://learn.adafruit.com/products/2890/guides) ![Double prototyping feather wing PCB with socket headers installed](https://cdn-shop.adafruit.com/640x480/2890-01.jpg) ### Adafruit Trinkey QT2040 - RP2040 USB Key with Stemma QT [Adafruit Trinkey QT2040 - RP2040 USB Key with Stemma QT](https://www.adafruit.com/product/5056) It's half USB Key, half Adafruit QT Py, and a lotta RP2040_..._it's  **Trinkey QT2040** , the circuit board with an RP2040 heart and Stemma QT legs. Folks are loving the [QT Py 2040](https://www.adafruit.com/product/4900) we made, but maybe you... In Stock [Buy Now](https://www.adafruit.com/product/5056) [Related Guides to the Product](https://learn.adafruit.com/products/5056/guides) ![Video of Trinkey RP2040 plugged into a laptop. An OLED display is connected and shows a graphic keyboard cat animation.](https://cdn-shop.adafruit.com/product-videos/640x480/5056-04.jpg) ## Simple Serial Printing Sketch First, load a sketch onto the microcontroller that you'll be plugging into the USB Host FeatherWing that prints something to the Serial Monitor. This quick example will print `hello world from another arduino!` every second. ```cpp void setup() { Serial.begin(115200); } void loop() { Serial.println("hello world from another arduino!"); delay(1000); } ``` ## Hardware Next, you can prepare the hardware for the demo. - Plug a non-ESP32 TinyUSB supported Feather and USB Host FeatherWing into a FeatherWing Doubler - Plug a microcontroller running an Arduino program that prints data to the Serial Monitor into the USB Host FeatherWing. A Trinkey QT2040 is shown in the Fritzing diagram. ![hacks_serialbridge.jpg](https://cdn-learn.adafruit.com/assets/assets/000/126/774/medium640/hacks_serialbridge.jpg?1703030889) ## Serial Host Bridge Example Load the example code onto your Feather after following the library installation instructions on the [Arduino Library Install page](https://learn.adafruit.com/adafruit-usb-host-featherwing-with-max3421e/arduino). Navigate to the **Adafruit TinyUSB Library Examples** and select **DualRole - CDC - serial\_host\_bridge** ![](https://cdn-learn.adafruit.com/assets/assets/000/126/780/medium800/hacks_exampleSerial.png?1703032929) https://github.com/adafruit/Adafruit_TinyUSB_Arduino/blob/master/examples/DualRole/CDC/serial_host_bridge/serial_host_bridge.ino After uploading the sketch to your board, open up the Serial Monitor ( **Tools -\> Serial Monitor** ) at 115200 baud. After you plug in your additional microcontroller to the USB Host FeatherWing, you see it mount and then print to the Serial Monitor thru the USB Host FeatherWing. ![](https://cdn-learn.adafruit.com/assets/assets/000/126/775/medium800/hacks_cdchost.png?1703031369) # Adafruit USB Host FeatherWing with MAX3421E ## Arduino Docs # Adafruit USB Host FeatherWing with MAX3421E ## Downloads ## Files - [MAX3421E Datasheet](https://cdn-learn.adafruit.com/assets/assets/000/126/624/original/max3421e.pdf?1702561777) - [EagleCAD PCB Files on GitHub](https://github.com/adafruit/Adafruit-USB-Host-FeatherWing-PCB) - [3D models on GitHub](https://github.com/adafruit/Adafruit_CAD_Parts/tree/main/5858%20USB%20Host%20FeatherWing) - [Fritzing object in the Adafruit Fritzing Library](https://github.com/adafruit/Fritzing-Library/blob/master/parts/Adafruit%20USB%20Host%20FeatherWing.fzpz) ## Schematic and Fab Print ![](https://cdn-learn.adafruit.com/assets/assets/000/126/622/medium800/hacks_schem.png?1702561666) ![](https://cdn-learn.adafruit.com/assets/assets/000/126/623/medium800/hacks_fab.png?1702561672 dimensions are in inches) ![](https://cdn-learn.adafruit.com/assets/assets/000/129/703/medium800/hacks_5858_USB_Host_FeatherWing.jpg?1714414518) ## Primary Products ### Adafruit USB Host FeatherWing with MAX3421E [Adafruit USB Host FeatherWing with MAX3421E](https://www.adafruit.com/product/5858) Lots of microcontrollers these days have USB ports on them, to program or debug, act like a keyboard or disk drive, or simply send data between a computer and your firmware. But did you know that you can also add a USB Host port? That means that your microcontroller project can have a... In Stock [Buy Now](https://www.adafruit.com/product/5858) [Related Guides to the Product](https://learn.adafruit.com/products/5858/guides) ## Featured Products ### FeatherWing Doubler - Prototyping Add-on For All Feather Boards [FeatherWing Doubler - Prototyping Add-on For All Feather Boards](https://www.adafruit.com/product/2890) This is the **FeatherWing Doubler** - a prototyping add-on and more for all Feather boards. This is similar to our [FeatherWing Proto](https://www.adafruit.com/products/2884) except there are two! The magic of the Doubler comes when stacking a Feather and another... In Stock [Buy Now](https://www.adafruit.com/product/2890) [Related Guides to the Product](https://learn.adafruit.com/products/2890/guides) ### FeatherWing Tripler Mini Kit - Prototyping Add-on For Feathers [FeatherWing Tripler Mini Kit - Prototyping Add-on For Feathers](https://www.adafruit.com/product/3417) This is the **FeatherWing Tripler** - a prototyping add-on and more for all Feather boards. This is similar to our [FeatherWing Proto](https://www.adafruit.com/products/2884) except there are three! The magic of the Tripler comes when you want to connect your Feather to... In Stock [Buy Now](https://www.adafruit.com/product/3417) [Related Guides to the Product](https://learn.adafruit.com/products/3417/guides) ### STEMMA Wired Potentiometer Breakout Board - 10K ohm Linear [STEMMA Wired Potentiometer Breakout Board - 10K ohm Linear](https://www.adafruit.com/product/4493) For the easiest way possible to measure twists, turn to this STEMMA potentiometer breakout (ha!). This plug-n-play pot comes with a JST-PH 2mm connector and a matching  [JST PH 3-Pin to Male Header Cables - 200mm](https://www.adafruit.com/product/3893), so wiring up is a cinch.... Out of Stock [Buy Now](https://www.adafruit.com/product/4493) [Related Guides to the Product](https://learn.adafruit.com/products/4493/guides) ### Adafruit ESP32-S2 Feather - 4 MB Flash + 2 MB PSRAM [Adafruit ESP32-S2 Feather - 4 MB Flash + 2 MB PSRAM](https://www.adafruit.com/product/5000) What's Feather-shaped and has an ESP32-S2 WiFi module? What has a STEMMA QT connector for I2C devices? What has your favorite Espressif WiFi microcontroller and lots of Flash and RAM memory for your next IoT project? What will make your next IoT project flyyyyy? That's right -... In Stock [Buy Now](https://www.adafruit.com/product/5000) [Related Guides to the Product](https://learn.adafruit.com/products/5000/guides) ### Adafruit Feather M4 Express - Featuring ATSAMD51 [Adafruit Feather M4 Express - Featuring ATSAMD51](https://www.adafruit.com/product/3857) It's what you've been waiting for, the Feather M4 Express featuring ATSAMD51. This Feather is fast like a swift, smart like an owl, strong like a ox-bird (it's half ox, half bird, OK?) This feather is powered by our new favorite chip, the **ATSAMD51J19** -  with... In Stock [Buy Now](https://www.adafruit.com/product/3857) [Related Guides to the Product](https://learn.adafruit.com/products/3857/guides) ## Related Guides - [Adafruit Feather M4 Express](https://learn.adafruit.com/adafruit-feather-m4-express-atsamd51.md) - [Adafruit ESP32-S2 Feather](https://learn.adafruit.com/adafruit-esp32-s2-feather.md) - [32x32 Square Pixel Art Animation Display](https://learn.adafruit.com/32x32-square-pixel-display.md) - [Air Quality Sensor 3D Printed Enclosure](https://learn.adafruit.com/air-quality-sensor-silo-house.md) - [CircuitPython 101: Working with Lists, Iterators and Generators](https://learn.adafruit.com/circuitpython-101-list-and-things-iterators-generators.md) - [Disconnected CO2 Data Logger](https://learn.adafruit.com/disconnected-co2-data-logger.md) - [Introducing Adafruit Feather](https://learn.adafruit.com/adafruit-feather.md) - [Animatronic Cosplay Wings](https://learn.adafruit.com/animatronic-cosplay-wings.md) - [Prop-Maker Lightsaber](https://learn.adafruit.com/lightsaber-featherwing.md) - [Sketch Drawing Toy with CircuitPython](https://learn.adafruit.com/sketch-drawing-toy.md) - [CircuitPython Motorized Camera Slider](https://learn.adafruit.com/circuitpython-motorized-camera-slider.md) - [Nunchuck Controlled Laser Cat Toy](https://learn.adafruit.com/nunchuck-controlled-laser-cat-toy.md) - [MIDI Melody Maker](https://learn.adafruit.com/midi-melody-maker.md) - [Holiday IoT Switch](https://learn.adafruit.com/holiday-iot-switch.md) - [IoT Air Quality Sensor with Adafruit IO](https://learn.adafruit.com/diy-air-quality-monitor.md) - [Playa Festival Bike](https://learn.adafruit.com/playa-festival-bike.md) - [CircuitPython 101: Functions](https://learn.adafruit.com/circuitpython-101-functions.md)