Pushbuttons often generate improper open/close transitions when pressed, due to mechanical and physical issues: these transitions may be read as multiple presses in a very short time fooling the program, without debouncing, pressing the button once may cause unpredictable results.

This library will sample the button repeatedly; and if it sees the button in its new state for 8 consequtive checks (equally spaced within 'delay' milli seconds) -- will report the state as changed.

Declare a ButtonDebouce object with pinNumber and timeMillis to debounce as parameter, and defined a callback function.

Example:

void onButtonChange(const int state) {
  Serial.println("Changed: " + String(state));
}
ButtonDebounce button(3, 250); // PIN 3 with 250ms debounce time
button.setCallback(onButtonChange);

Or - in a more asynchroneous style:

void onButtonChange(const int state) {
  Serial.println("Changed: " + String(state));
}
ButtonDebounce button(3, 250); // PIN 3 with 250ms debounce time
button.setCallback([](const int state) {
  Serial.println("Changed: " + String(state));
});

Important: buttons don´t share resources. The following methods are avaliable.

• update() called in loop method, used to verify the debounce timer and the button state changes.
• state() return the last button state.
• setCallback(function) set the callback function that will executed on button state changes.

Note that the constructor also sets the INPUT_PULLUP pinmode() on the pin.

Due the time buffer used in each button, please call the update() method in loop, so it can be update and reflect all state changes.

Be advised: Do not declare any delay() before the update functions, as it may interfere with the bounce time buffer.

void loop() {
  buttonUp.update();
  buttonDown.update();
}

Thank you for all contributions:

• per1234
• Italo Souza
• Dirk-Willem van Gulik
• abaskin