Keyboard Logout

This example uses the Keyboard library to log you out of your user session on your computer when pin 2 on your Leonardo, Micro or Due is pulled to ground. The sketch simulates the keypress in sequence of two or three keys at the same time and after a short delay it releases them.

NB: When you use the Keyboard.print() command, the Arduino takes over your computer's keyboard! To insure you don't lose control of your computer while running a sketch with this function, make sure to set up a reliable control system before you call Keyboard.print(). This sketch is designed to only send a Keyboard command after a pin has been pulled to ground.

Hardware Required

  • Arduino Leonardo, Micro, or Due board
  • pushbutton
  • hook-up wires
  • breadboard

Circuit

click the image to enlarge

image developed using Fritzing. For more circuit examples, see the Fritzing project page

Schematic

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Code

Before you upload the program to your board, make sure to assign the correct OS you are currently using to the platform variable.

While the sketch is running, pressing the button will connect pin 2 to ground and the board will send the logout sequence to the USB connected pc.

/*
  Keyboard logout

 This sketch demonstrates the Keyboard library.

 When you connect pin 2 to ground, it performs a logout.
 It uses keyboard combinations to do this, as follows:

 On Windows, CTRL-ALT-DEL followed by ALT-l
 On Ubuntu, CTRL-ALT-DEL, and ENTER
 On OSX, CMD-SHIFT-q

 To wake: Spacebar.

 Circuit:
 * Arduino Leonardo or Micro
 * wire to connect D2 to ground.

 created 6 Mar 2012
 modified 27 Mar 2012
 by Tom Igoe

 This example is in the public domain

 http://www.arduino.cc/en/Tutorial/KeyboardLogout
 */


#define OSX 0
#define WINDOWS 1
#define UBUNTU 2

#include "Keyboard.h"

// change this to match your platform:
int platform = OSX;

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() {
  while (digitalRead(2) == HIGH) {
    // do nothing until pin 2 goes low
    delay(500);
  }
  delay(1000);

  switch (platform) {
    case OSX:
      Keyboard.press(KEY_LEFT_GUI);
      // Shift-Q logs out:
      Keyboard.press(KEY_LEFT_SHIFT);
      Keyboard.press('Q');
      delay(100);
      Keyboard.releaseAll();
      // enter:
      Keyboard.write(KEY_RETURN);
      break;
    case WINDOWS:
      // CTRL-ALT-DEL:
      Keyboard.press(KEY_LEFT_CTRL);
      Keyboard.press(KEY_LEFT_ALT);
      Keyboard.press(KEY_DELETE);
      delay(100);
      Keyboard.releaseAll();
      //ALT-l:
      delay(2000);
      Keyboard.press(KEY_LEFT_ALT);
      Keyboard.press('l');
      Keyboard.releaseAll();
      break;
    case UBUNTU:
      // CTRL-ALT-DEL:
      Keyboard.press(KEY_LEFT_CTRL);
      Keyboard.press(KEY_LEFT_ALT);
      Keyboard.press(KEY_DELETE);
      delay(1000);
      Keyboard.releaseAll();
      // Enter to confirm logout:
      Keyboard.write(KEY_RETURN);
      break;
  }

  // do nothing:
  while (true);
}

See Also


Last revision 2015/07/29 by SM

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