Pressing multiple keys using USBKeyboard library on Arduino Nano 33 BLE Sense

Projects Interfacing w/ Software on the Computer
1

Hi @Klaus_K

I am currently using a Arduino Nano 33 BLE Sense board for my project. I want to press ALT + F4 keys when a signal is triggered. Since this is an mbed_os board, I am using the USBKeyboard.h library. But the issue is, I am able to press only one key at a time. I am not able to press ALT+F4 simultaneously

key.key_code(KEY_F4, KEY_ALT);
delay(100);
key.key_code(KEY_NONE);

where

#define KEY_F4 0x3d

Can someone help me as to how do I get around implementing this?

Thanks and regards

2

Welcome to the forum.

First, can you please confirm where you got the library from (e.g., provide a link to Github) and post a complete sketch. This will allow others to test this without writing a sketch first and search for the library. Often libraries have the same name for a header file but are different.

If you use this library https://www.arduino.cc/reference/en/language/functions/usb/keyboard/ have a look at the following page

https://www.arduino.cc/reference/en/language/functions/usb/keyboard/keyboardmodifiers

Without testing this, I suspect both your keys are keyboardmodifiers and therefore the library cannot handle your use case. This is just a guess.

Try using ALT and some Letter and see what happens. Or maybe SHIFT. See if you can get small and capital letters printed into a notepad window.

3

Like a keyboard macro programmable key
Make Your Own Custom Shortcut Buttons With an Arduino (makeuseof.com)

4

I believe you are looking for keyboard decoder library with "two-key rollover" which will reliably detect only any two keys used simultaneously ; in other words, you can can hold down your ALT on the keyboard and press a + key and be sure that the keypress is correctly detected by the computer. Check if it will support N-Key_Rollover.

7

If you look at the library source code, the function key_code() allows two parameter. You are only using one.

https://github.com/arduino/ArduinoCore-nRF528x-mbedos/blob/master/libraries/USBHID/USBKeyboard.cpp

bool USBKeyboard::key_code(uint8_t key, uint8_t modifier)

The values for the keys are at the beginning of the file.

8

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