Need help with debouncing multiple switches in an existing sketch

I am trying to debounce switches in an existing sketch that I am wanting to use. Have tried a few methods of debouncing that I found on various places on the net but can't get it integrated in what I already have and as a newbie I am at a loss. The relevant parts of the sketch are:

void setup()

// For pushButtons:
int pushButton = 0;

void loop() {

  if (digitalRead(22))  {
    if (pushButton !=22)  {
      Serial.println("Input 1");
  } else if (pushButton==22) {
    pushButton = 0; 

  if (digitalRead(23))  {
    if (pushButton !=23)  {
      Serial.println("Select 2");
  } else if (pushButton==23) {
    pushButton = 0; 

I have shown only two of the fifteen switches. I get debounce errors both at the make and the break. Any and all help is appreciated.

I have shown only two of the fifteen switches. I get debounce errors both at the make and the break. Any and all help is appreciated.

Here is some code you can use for any number of mechanical buttons and switches:

#define BOUNCETIME 5              // bouncing time in milliseconds
byte buttonPins[]={2, 3, 4, 5, 6};// pin numbers of all buttons
#define NUMBUTTONS sizeof(buttonPins) // number of buttons (automatically calculated)
byte buttonState[NUMBUTTONS];  // array holds the actual HIGH/LOW states
byte buttonChange[NUMBUTTONS]; // array holds the state changes when button is pressed or released

void input(){
// read the input state and state changes of all buttons
  static unsigned long lastButtonTime; // time stamp for remembering the time when the button states were last read
  memset(buttonChange,0,sizeof(buttonChange)); // reset all old state changes
  if (millis()-lastButtonTime<BOUNCETIME) return;  // within bounce time: leave the function
  lastButtonTime=millis(); // remember the current time
  for (int i=0;i<NUMBUTTONS;i++) 
    byte curState=digitalRead(buttonPins[i]);        // current button state
    if (INPUTMODE==INPUT_PULLUP) curState=!curState; // logic is inverted with INPUT_PULLUP
    if (curState!=buttonState[i])                    // state change detected
      if (curState==HIGH) buttonChange[i]=BUTTONDOWN;
      else buttonChange[i]=BUTTONUP;
    buttonState[i]=curState;  // save the current button state

void output(){
// send a message to Serial if a button state (pressed/released) has changed
// button pressed: Send button pin number with minus sign
// button released: Send button pin number
  byte action;
  for (int i=0;i<NUMBUTTONS;i++)
    switch (buttonChange[i])  
      case BUTTONUP: Serial.println(buttonPins[i]);break;
      case BUTTONDOWN: Serial.println(-buttonPins[i]);break;

void setup() {
  Serial.begin(9600); // initialize Serial at 9600 baud
  // then initialize all buttons
  for (int i=0;i<NUMBUTTONS;i++) pinMode(buttonPins[i],INPUTMODE);

void loop() {
  // processing(); // if you need any processing, write a function for it!  

I’m always using the IPO programming model for arduino sketches in the loop:

  • input
  • processing
  • output

In the code define INPUTMODE accordingly to the usage of pull-resistors in your circuit:

  • when using no pull-resistors or external pull-up resistors ==> INPUT_PULLUP
  • when using external pull-down resistors ==> INPUT

In the demo sketch, input is taken from the buttons, not any processing is done, and the output is a short message on Serial when a button was pressed or released.

Are you sure that there is a bounce problem that needs to be fixed?

What about reading all the buttons within a single function and having a short wait between calls to the function

void readButtons() {
   if (millis() - prevMillis >= 50) {
      prevMillis = millis();
      buttonAstate = digitalRead(buttonApin);
      // etc etc


Thanks guys. I'll try those suggestions.