5-Button-Keyboard-Diagram.jpg
=KEYBOARDS and MULTIPLE BUTTONS
external image detail_334_02.jpg

5-Button Keyboard: Uses series resistors and switches to decide a variety of voltages to send to an Arduino Analog Input.
You can use this same technique for multiple buttons you mount in other ways or orientations.
Diagram:




Below: (UPDATED 1/17) Example code of a 5-button keyboard that uses resistors to connect to a single Analog Input Pin:

/* YourDuinoStarter Example: Analog buttons
  - WHAT IT DOES: Reads Analog Input 0 and decodes which button was pressed
  - SEE the comments after "//" on each line below
  - V2.0 01-06-2017
   Questions: terry@yourduino.com
*/

/*-----( Import needed libraries )-----*/
//None
/*-----( Declare Constants and Pin Numbers )-----*/

#define LEDPIN 13

#define keyboard_AnalogInput 0   // Analog input 0 used for Keyboard

#define btnRIGHT  4
#define btnUP     2
#define btnDOWN   3
#define btnLEFT   1
#define btnENTER  5
#define btnNONE   -1

/*---( declare Variables )----*/

int buttonpressed;

void setup()   /****** SETUP: RUNS ONCE ******/
{
  pinMode(LEDPIN, OUTPUT);
  Serial.begin(115200);          // Set Serial Monitor lower right to 115200
  Serial.println("Testing Analog Buttons ");
}//--(end setup )---

void loop()   /****** LOOP: RUNS CONSTANTLY ******/
{
  buttonpressed = read_keyboard();
  if (buttonpressed != btnNONE)
  {
    Serial.print(" Button Pressed = ");
    Serial.println(buttonpressed);
  }

}//--(end main loop )---

/*---( User Written Functions )------*/
/*-----------( Read analog values from 4-button keyboard, decode voltages to Buttons )---------------*/
int getButton()
{
  int i, v, button;
  int sum = 0;

  for (i = 0; i < 4; i++) {
    sum += analogRead(keyboard_AnalogInput);
  }
  v = sum / 4;
  if (v > 1000) button = 0;
  else if (v >= 0  && v < 20)  button = 1; //LEFT
  else if (v > 135 && v < 155) button = 2; //UP
  else if (v > 315 && v < 335) button = 3; //DOWN
  else if (v > 495 && v < 515) button = 4; //RIGHT
  else if (v > 725 && v < 745) button = 5; //ENTER
  else button = 0;
 
  return button;
}// END getButton

/*-------------------( Debounce keystrokes, translate to buttons )-------------------*/
int old_button = 0;
int read_keyboard()
{
  int button, button2, pressed_button;
  button = getButton();         // Above
  if (button != old_button)     // A new button pressed
  {
    delay(50);                // debounce
    button2 = getButton();
    if (button == button2)
    {
      old_button = button;
      pressed_button = button;
      if (button != 0)
      {
        //Serial.println(button);
        if (button == 1) return btnLEFT;
        if (button == 2) return btnUP;
        if (button == 3) return btnDOWN;
        if (button == 4) return btnRIGHT;
        if (button == 5) return btnENTER;
      }
    }
  }
  else
  {
    return btnNONE;
  }
}// End read_keyboard

//*********( THE END )**********