// ECG arduino code - v2 - Sep13 - Alan Blackham

// ecg.htm



#define ANALOG_IN 0

int sensorPin = A0;              // select the input pin for the potentiometer
long sensorValue = sensorValue;  // variable to store the value coming from the sensor
int sounder = 11;                // sounder
int led = 13;                    // led
unsigned long ptime=millis();    // store for time of last pulse


void setup() {
  
  // initialize the serial communication:
  Serial.begin(9600);
  
  pinMode(sounder, OUTPUT);  // sounder pin
  digitalWrite(sounder, LOW);    // turn sounder off
  
  pinMode(led, OUTPUT);     // led pin
  digitalWrite(led, LOW);    // turn led off

}


void loop() {
  
  // read the value from the sensor and send via serial once 
  int val = analogRead(ANALOG_IN);
  Serial.println( val );
  
  // if reading high then log as a pulse
  if (val > 300) {   // if pulse detected
     if ((millis()-ptime) > 300) {   // if not to soon since last one
       // pulse detected
       digitalWrite(sounder, HIGH);   // turn sounder on
       
     }
     ptime = millis();   // update time of last pulse
  }
  
  // flash led and set timing
  digitalWrite(led, HIGH);    // turn led off
  delayMicroseconds(5000);    // pause 5ms
  digitalWrite(led, LOW);     // turn led off
  delayMicroseconds(4650);    // pause 5ms (tweaked to get timing spot on)
    
  digitalWrite(sounder, LOW);    // turn sounder off  

}
// end