PiTX - Arduino Code - v1.txt

const int buttonPin = 3;
const int relayPin = 0;
const int uartPin = 4;
const int shutdownPin = 2;

int shutdownComplete = 1;
unsigned long time;
unsigned long oldTime;


void setup() {    
  pinMode(relayPin, OUTPUT);  // Controls transistor for relay
  pinMode(buttonPin, INPUT);  // From switch
  pinMode(uartPin, INPUT);  // From UART TX of Pi
}

void loop(){

  if (digitalRead(uartPin) == LOW) { // The Pi is off
    if (digitalRead(buttonPin) == HIGH) { // And button is pressed
      digitalWrite(relayPin, HIGH); // Turn on relay
      shutdownComplete = 0; // Check to see if the Pi has recently shutdown
      delay(10000); // Wait 10 secs for UART to stabilise
    } 
    else {
      //      if ( digitalRead(uartPin) == LOW) { // If UART goes low, it signals Pi is rebooted or halted
      if ( shutdownComplete == 0 ) { // If Pi has shutdown or just rebooting
        delay(5000); // If it's rebooted, we will wait to see if UART goes high
      }
      if ( digitalRead(uartPin) == LOW) { // If it doesn't, we assume it's halted, so kill the relay
        digitalWrite(shutdownPin, LOW);
        digitalWrite(relayPin, LOW);
        shutdownComplete = 1;
      }

    }
  } 
  else {
    if (digitalRead(buttonPin) == HIGH) {
      delay(3000);
      if (digitalRead(buttonPin) == HIGH) {
        digitalWrite(relayPin, LOW);
        digitalWrite(shutdownPin, LOW);
        shutdownComplete = 1;
      } 
      else {
        digitalWrite(shutdownPin, HIGH);
      }
    }
  }
}