//XIAO RP2040
// LED State Machine
// Press button to toggle LED state
// LED @D8 (1 ON, 0 OFF)
// PB @D9 (1 OPEN, 0 CLOSED)
//

// constants won't change. They're used here to set pin numbers:
const int buttonPin = D9;  // the number of the pushbutton pin
const int ledPin = D8;    // the number of the LED pin
int ledState = 0;         // start with 

void setup() {
  // set pin directions
  pinMode(ledPin, OUTPUT);
  // initialize the pushbutton pin as an input:
  pinMode(buttonPin, INPUT);  // use INPUT_PULLUP or INPUT_PULLDOWN if using internal resistor
}

void loop() {
  // wait for keypress
  buttonState = digitalRead(buttonPin);
  
  if (digitalRead(buttonPin) == 0) {    //buttonpin pressed
      delay(15);                       //switch debounce
      while (digitalRead (buttonPin) == 0);    //wait for buttonPin realease
      if (ledState == 0)                // current state 0
       ledState = 1;                    // update state
      else
       ledState = 0;                    //ledState = 1, reset to 0    
  } 

  // Update LED depending on ledState
  if (ledState == 0)
    digitalWrite(ledPin, HIGH);            // turn off LED
  else if (ledState == 1)
    digitalWrite(ledPin, LOW);             // turn off LED
}