/*
  DigitalReadSerial
  Reads a digital input on pin 6, prints the result to the serial monitor

  This example code is in the public domain.
*/

#define SYSTEM_ON 3   //Blue push button
#define PANEL_POWER 6 //Red LED

int latchState = LOW;   //to latch the input of SYSTEM_ON
int currentState = LOW; //to indicate the current state of SYSTEM_ON
int lastState = LOW;    //to indicate the last state of SYSTEM_ON
void setup()
{
  Serial.begin(9600);
  pinMode(SYSTEM_ON, INPUT);
  pinMode(PANEL_POWER, OUTPUT);
}

void loop()
{
  currentState = digitalRead(SYSTEM_ON);        //reads the current input of push button ,i.e, SYSTEM_ON

  if (currentState == HIGH && lastState == LOW) //detects a low to high transistion of input SYSTEM_ON, ie, when button is pressed
  {
    latchState = !latchState;                   //negates the latch state when the button is pressed
  }

  lastState = currentState;                     //stores the current state as last state and the loop executes again

  if (latchState == HIGH)
  {
    digitalWrite(PANEL_POWER, HIGH);            //PANEL_POWER ,ie, red LED glows when the switch is pressed once and goes off the next time
  }
  else
  {
    digitalWrite(PANEL_POWER, LOW);
  }

  /*
    Prints the current state and latch state of PANEL_POWER in the serial monitor for reference.
    Added a delay of 500ms to see the values displayed in serial monitor.
  */
  Serial.print("currentState =");
  Serial.println(currentState);
  Serial.print("latchState =");
  Serial.println(latchState);
  Serial.println();
  delay(250);
}