Once the Arduino is programed and the 16U2 is flashed, plug the arduino into a Windows computer and let the USB keyboard drivers install as normal. Then wait between 1 and 10 minutes for a random ...

Connect to the Arduino from the modern device over USB serial at 9600 baud (using the Arduino Serial Monitor, for example). Key events coming from the NABU keyboard will be printed over serial.

The USB keyboard in boot protocol mode is unsophisticated piece of hardware which sends out 8-byte packet showing which keys are pressed. A byte can also be sent that states which LEDs have to be ...

This could make for an excellent controller or debugger for embedded systems. The Arduino, shield, and LCD could be integrated into the keyboard itself with an I/O port for connecting to your project.

This is the single most important piece of hardware you’re going to need to connect a USB keyboard to your phone, and there’s no real way around it.