Arduino Reference

Keyboard.write()

Description

Sends a keystroke to a connected computer. This is similar to pressing and releasing a key on your keyboard. You can send some ASCII characters or the additional keyboard modifiers and special keys.

Only ASCII characters that are on the keyboard are supported. For example, ASCII 8 (backspace) would work, but ASCII 25 (Substitution) would not. When sending capital letters, Keyboard.write() sends a shift command plus the desired character, just as if typing on a keyboard. If sending a numeric type, it sends it as an ASCII character (ex. Keyboard.write(97) will send 'a').

For a complete list of ASCII characters, see ASCIITable.com.

Syntax

Keyboard.write(character)

Parameters

character : a char or int to be sent to the computer. Can be sent in any notation that’s acceptable for a char. For example, all of the below are acceptable and send the same value, 65 or ASCII A:

Keyboard.write(65);         // sends ASCII value 65, or A
Keyboard.write('A');            // same thing as a quoted character
Keyboard.write(0x41);       // same thing in hexadecimal
Keyboard.write(0b01000001); // same thing in binary (weird choice, but it works)

Returns

size_t : number of bytes sent.

Example Code

#include <Keyboard.h>

void setup() {
  // make pin 2 an input and turn on the
  // pullup resistor so it goes high unless
  // connected to ground:
  pinMode(2, INPUT_PULLUP);
  Keyboard.begin();
}

void loop() {
  //if the button is pressed
  if (digitalRead(2) == LOW) {
    //Send an ASCII 'A',
    Keyboard.write(65);
  }
}

Notes and Warnings

When you use the Keyboard.write() command, the Arduino takes over your keyboard! Make sure you have control before you use the command. A pushbutton to toggle the keyboard control state is effective.