// This debouncer validates a button press only after the debounce timeout.

byte buttonpin[] = { 5, 6, 7, 4, 3, 2 };                      // declare button pins in an array
byte element;                                                 // indicates pressed button/pin
byte buttonArray = sizeof(buttonpin) / sizeof(buttonpin[0]);  // get number of elements in button array

unsigned long timer;          // timer keeps track of length of button press (or noise/ringing).
unsigned long timeout = 100;  // timeout (in milliseconds) is the minimum for "a button is pressed".

byte redPin = 11, grnPin = 9, bluPin = 8;  // pins for the common cathode RGBLED

void setup() {
  Serial.begin(115200);                   // start serial monitor
  for (int i = 0; i < buttonArray; i++)   // count to number of elements in button array
    pinMode(buttonpin[i], INPUT_PULLUP);  // configure button pins for reading (LOW when pressed)
}

void loop() {
  if (element > buttonArray)                  // count through array... do not use for() loops. they blocking program flow.
    element = 0;                              // if beyond the array size, start again from the first element
  if (!digitalRead(buttonpin[element])) {     // button may have been pressed, or just noise/ringing
    if (millis() - timer > timeout) {         // measure time from last "press" to this "press. replaces delay();
      if (digitalRead(buttonpin[element])) {  // valid button was released after debounce timeout
        timer = millis();                     // reset timer after valid button press
        switch (element) {
          case 0: blk(); break;
          case 1: wht(); break;
          case 2: yel(); break;
          case 3: blu(); break;
          case 4: grn(); break;
          case 5: red(); break;
          default: break;
        }
      }
    }
  }
  element++;  // check next array element 
}

void blk() { digitalWrite(redPin,  LOW); digitalWrite(grnPin,  LOW); digitalWrite(bluPin,  LOW); }
void wht() { digitalWrite(redPin, HIGH); digitalWrite(grnPin, HIGH); digitalWrite(bluPin, HIGH); }
void yel() { digitalWrite(redPin, HIGH); digitalWrite(grnPin, HIGH); digitalWrite(bluPin,  LOW); }
void blu() { digitalWrite(redPin,  LOW); digitalWrite(grnPin,  LOW); digitalWrite(bluPin, HIGH); }
void grn() { digitalWrite(redPin,  LOW); digitalWrite(grnPin, HIGH); digitalWrite(bluPin,  LOW); }
void red() { digitalWrite(redPin, HIGH); digitalWrite(grnPin,  LOW); digitalWrite(bluPin,  LOW); }