Arduino Keyboards-MultipleButtons

Keyboards-MultipleButtons

源自於 

https://arduino-info.wikispaces.com/Keyboards-MultipleButtons

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 (right):

Below: Example code of a 5-button keyboard that uses resistors to connect to a single Analog Input Pin:

/* YourDuino Example 5 Button Analog Keyboard 
 5-button keyboard connected to Analog Input 0
 terry@yourduino.com */

/*-----( Import needed libraries )-----*/
/*-----( Declare Constants and Pin Numbers )-----*/

#define keyboard_AnalogInput 0

#define btnRIGHT  0
#define btnUP     1
#define btnDOWN   2
#define btnLEFT   3
#define btnENTER 4
#define btnNONE   5
/*-----( Declare objects )-----*/
/*-----( Declare Variables )-----*/

int adc_key_in = 0;
int buttonPressed;

void setup()   /****** SETUP: RUNS ONCE ******/
{
  Serial.begin(9600);
  Serial.println("Test 5-button keyboard");
 }   //--(end setup )---


void loop()   /****** LOOP: RUNS CONSTANTLY ******/
{
  buttonPressed = read_keyboard();
  if (buttonPressed != btnNONE)
  {
    Serial.print("OK - That looks like you pressed ");
    Serial.println(buttonPressed, DEC);
  } 
  delay(500);

}  //--(end main loop )---

/*-----( Declare User-written Functions )-----*/
// read the buttons
int read_keyboard()
{
  adc_key_in = analogRead(keyboard_AnalogInput); 
  // read the value from the sensor
  // buttons when read are centered at these values: 0, 144, 329, 504, 741
  // add approx 50 to those values and check to see if we are close
  if (adc_key_in > 1000) return btnNONE; 
  if (adc_key_in < 50) return btnRIGHT;
  if (adc_key_in < 195) return btnUP;
  if (adc_key_in < 380) return btnDOWN;
  if (adc_key_in < 555) return btnLEFT;
  if (adc_key_in < 790) return btnENTER;
  return btnNONE; // when all others fail, return this...
}


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