uno-HID-keyboard

This project demonstrates how to use an Arduino Uno, equipped with an ATmega16u2 chip, and simple button circuit to function as an HID keyboard. Including examples of using the device as a piano key input for VST or MIDI players.

Tested Devices/OS:

• Arduino Uno R3
• Windows 10/11 (via Notepad & VMPK)
• Linux: Ubuntu, Raspberry (via Text Editor & VMPK)

Prerequisite

• Arduino Uno R3
• Buttons
• 10K Resistor
• Wire
• Jumper Cap
• Breadboard/Perfboard
• Flip (Requires Java Runtime Environment)
• VMPK (Optional)

Circuit

The circuit is using a simple button configuration. The 10K resistors are used as pull down resistors, ensuring that the pins are as close to 0V as possible when no external signal is present. Use this as a reference for the provided examples.

Flashing HID firmware with Flip

Use genuine Arduino only since fake or clone integrated with CH340 chip which cannot be used for DFU purposes and not supported by this guide.

To install HID firmware connect your arduino to the PC. To get into DFU mode. If you want make changes with your code, you can always change back to original firmware.

Install Flip and Java Runtime Environment first. Then connect arduino to computer.

Short these two pins using wire or jumper cap (recommended) and pull out. You can notice the arduino entering DFU mode by disconnecting and connecting sound from your OS.

img ref: https://store.arduino.cc/products/arduino-uno-rev3

The device should show up in device manager as Atmega16u2. If not or if you get the error "AtLibUsbDfu.dll not found" install the drivers manually from the device manager. Normally it should be in

C:\Program Files (x86)\Atmel\Flip 3.4.7\usb 

right click the .inf file and click install.

Inside Flip, Click on the IC button and select Atmega16u2

Click File -> Load Hex File and select the firmware.

Click run to upload the firmware and replug the Arduino. Now Arduino become HID device.

Testing

There are various methods to test your HID devices, but the easiest options include:

• Text Editor Open your preferred text editor to test your input. Simply type using the HID device to ensure it is functioning correctly.

• VMPK Download and install VMPK or a similar software. Use the HID device to test the input by pressing individual keys or playing chords.

References

Arduino-usbserial-uno.hex: https://github.com/arduino/ArduinoCore-avr/blob/master/firmwares/atmegaxxu2/arduino-usbserial/Arduino-usbserial-uno.hex

Arduino-keyboard-0.3.hex: https://github.com/coopermaa/USBKeyboard/blob/master/firmware/Arduino-keyboard-0.3.hex