I'm using a ItsyBitsy 32u4, Adafruit says it can act as a USB HID keyboard. The mc is based on the 32u4 which the Keyboard docs say are supported.

I have a simple sketch that prints "A" every second and should press "A". When I upload the sketch and connect to the serial port I see the print output but I don't get any key presses.

Any ideas? I'm on linux, I suspect that the controller doesn't register as a HID device, maybe I need UDEV rules or drivers?

EDIT: the keyboard works on a different computer.

#include <Keyboard.h>
void setup() {

void loop() {
  • you shoukd read the reference and study the examples
    – Juraj
    Commented Jul 5, 2019 at 6:42
  • @Juraj I have, what do you think I missed? Commented Jul 5, 2019 at 17:42
  • it seemed you missed what is in the Answer. do you have a text editor open in foreground?
    – Juraj
    Commented Jul 5, 2019 at 20:18
  • Yeah, I have a window focused that accepts and displays keyboard input. Typing on my actual keyboard displays the keys. Commented Jul 5, 2019 at 22:32
  • next I would try removing Serial from the sketch
    – Juraj
    Commented Jul 6, 2019 at 5:18

2 Answers 2


Keyboard.press() expects a character, but you are passing a character array. Also Keyboard.press() only presses but does not release the key. Keyboard.releaseAll() can be used to release all keys.

I would try:

Keyboard.press('A') ;  //note the ' instead of "

or preferably:

Keyboard.write('A');   //handles press and release of basic keys
  • I made an error when I created my simple repo sketch, but I have tried Keyboard.press('A') and Keyboard.write('A'). Neither work. Commented Jul 5, 2019 at 17:31
  • I also tried Keyboard.write('a') after reading keyboard.cpp and realizing that writing 'A' sends keypesses for a and the shift modifier. Commented Jul 5, 2019 at 17:44

There was some issue with my laptop, not controller or the sketch.

I tried the my board with another computer and it worked. I tried a commercial keyboard on my first computer it also didn't work.

Both keyboards work after a reboot.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.