#pulsesensor

This Guy Mapped His Heart Rate During 'Game Of Thrones' 

"If you've even watched a few episodes of the HBO series Game of Thrones, you know it is an abusive, heart-hardening show. As soon as you get attached, whoops, your favorite character is dead, and you promise yourself you'll never love again--it'll only lead to more heartache, after all. But then, you slowly come to realize, maybe this other character will give you new hope--but, nope, wait, they're also dead. Or are they??? No. They are dead.

Arduino Pulse Sensor

Deleted nonsense code. Made the in between pulse reading not as noisy aka the light bulb doesn't go crazy!

/*

>> Pulse Sensor Digital Filter <<

This code is the library prototype for Pulse Sensor by Yury Gitman and Joel Murphy

    www.pulsesensor.com 

    >>> Pulse Sensor purple wire goes to Analog Pin 0 <<<

Pulse Sensor sample aquisition and processing happens in the background via Timer 1 interrupt. 1mS sample rate.

The following variables are automatically updated:

Pulse :     boolean that is true when a heartbeat is sensed then false in time with pin13 LED going out.

Signal :    int that holds the analog signal data straight from the sensor. updated every 1mS.

HRV  :      int that holds the time between the last two beats. 1mS resolution.

B  :        boolean that is made true whenever HRV is updated. User must reset.

BPM  :      int that holds the heart rate value. derived from averaging HRV every 10 pulses.

QS  :       boolean that is made true whenever BPM is updated. User must reset.

Scale  :    int that works abit like gain. use to change the amplitude of the digital filter output. useful range 12<>20 : high<>low default = 12

FSignal  :  int that holds the output of the digital filter/amplifier. updated every 1mS.

See the README for detailed information and known issues.

Code Version 0.6 by Joel Murphy  December 2011  Happy New Year! 

*/

int timer = 0;

long previousMillis = 0;        // will store last time LED was updated

long interval = 1000;           // interval at which to blink (milliseconds)

long Hxv[4]; // t1hese arrays are used in the digital filter

long Hyv[4]; // H for highpass, L for lowpass

long Lxv[4];

long Lyv[4];

unsigned long readings; // used to help normalize the signal

unsigned long peakTime; // used to time the start of the heart pulse

unsigned long lastPeakTime = 0;// used to find the time between beats

volatile int Peak;     // used to locate the highest point in positive phase of heart beat waveform

int rate;              // used to help determine pulse rate

volatile int BPM;      // used to hold the pulse rate

int offset = 0;        // used to normalize the raw data

int sampleCounter;     // used to determine pulse timing

int beatCounter = 1;   // used to keep track of pulses

volatile int Signal;   // holds the incoming raw data

int NSignal;           // holds the normalized signal 

volatile int FSignal;  // holds result of the bandpass filter

volatile int HRV;      // holds the time between beats

volatile int Scale = 13;  // used to scale the result of the digital filter. range 12<>20 : high<>low amplification

volatile int Fade = 0;

boolean first = true; // reminds us to seed the filter on the first go

volatile boolean Pulse = false;  // becomes true when there is a heart pulse

volatile boolean B = false;     // becomes true when there is a heart pulse

volatile boolean QS = false;      // becomes true when pulse rate is determined. every 20 pulses

int pulsePin = 0;  // pulse sensor purple wire connected to analog pin 0

void setup(){

pinMode(13,OUTPUT);    // pin 13 will blink to your heartbeat!

Serial.begin(115200); // we agree to talk fast!

// this next bit will wind up in the library. it initializes Timer1 to throw an interrupt every 1mS.

TCCR1A = 0x00; // DISABLE OUTPUTS AND BREAK PWM ON DIGITAL PINS 9 & 10

TCCR1B = 0x11; // GO INTO 'PHASE AND FREQUENCY CORRECT' MODE, NO PRESCALER

TCCR1C = 0x00; // DON'T FORCE COMPARE

TIMSK1 = 0x01; // ENABLE OVERFLOW INTERRUPT (TOIE1)

ICR1 = 8000;   // TRIGGER TIMER INTERRUPT EVERY 1mS  

sei();         // MAKE SURE GLOBAL INTERRUPTS ARE ENABLED

}

void loop(){

     unsigned long currentMillis = millis();

  if(currentMillis - previousMillis > interval) {

    // save the last time you blinked the LED 

    previousMillis = currentMillis; 

    timer = 1;

  }  

        if (B == true){             //  B is true when arduino finds the heart beat

    B = false;                // reseting the QS for next time

  }

  if (QS == true){            //  QS is true when arduino derives the heart rate by averaging HRV over 20 beats

    QS = false;               //  reset the B for next time

  }

  Fade -= 15;

  Fade = constrain(Fade,0,255);

  analogWrite(11,Fade);

   //delay(20);                    //  take a break

}

// THIS IS THE TIMER 1 INTERRUPT SERVICE ROUTINE. IT WILL BE PUT INTO THE LIBRARY

ISR(TIMER1_OVF_vect){ // triggered every time Timer 1 overflows

// Timer 1 makes sure that we take a reading every milisecond

Signal = analogRead(pulsePin);

// First normailize the waveform around 0

readings += Signal; // take a running total

sampleCounter++;     // we do this every milisecond. this timer is used as a clock

if ((sampleCounter %300) == 0){   // adjust as needed

  offset = readings / 300;        // average the running total

  readings = 0;                   // reset running total

}

NSignal = Signal - offset;        // normalizing here

// IF IT'S THE FIRST TIME THROUGH THE SKETCH, SEED THE FILTER WITH CURRENT DATA

if (first = true){

  for (int i=0; i<4; i++){

    Lxv[i] = Lyv[i] = NSignal <<10;  // seed the lowpass filter

    Hxv[i] = Hyv[i] = NSignal <<10;  // seed the highpass filter

  }

first = false;      // only seed once please

}

// THIS IS THE BANDPAS FILTER. GENERATED AT www-users.cs.york.ac.uk/~fisher/mkfilter/trad.html

//  BUTTERWORTH LOWPASS ORDER = 3; SAMPLERATE = 1mS; CORNER = 5Hz

    Lxv[0] = Lxv[1]; Lxv[1] = Lxv[2]; Lxv[2] = Lxv[3];

    Lxv[3] = NSignal<<10;    // insert the normalized data into the lowpass filter

    Lyv[0] = Lyv[1]; Lyv[1] = Lyv[2]; Lyv[2] = Lyv[3];

    Lyv[3] = (Lxv[0] + Lxv[3]) + 3 * (Lxv[1] + Lxv[2])

          + (3846 * Lyv[0]) + (-11781 * Lyv[1]) + (12031 * Lyv[2]);

//  Butterworth; Highpass; Order = 3; Sample Rate = 1mS; Corner = .8Hz

    Hxv[0] = Hxv[1]; Hxv[1] = Hxv[2]; Hxv[2] = Hxv[3];

    Hxv[3] = Lyv[3] / 4116; // insert lowpass result into highpass filter

    Hyv[0] = Hyv[1]; Hyv[1] = Hyv[2]; Hyv[2] = Hyv[3];

    Hyv[3] = (Hxv[3]-Hxv[0]) + 3 * (Hxv[1] - Hxv[2])

          + (8110 * Hyv[0]) + (-12206 * Hyv[1]) + (12031 * Hyv[2]);

FSignal = Hyv[3] >> Scale;  // result of highpass shift-scaled

//PLAY AROUND WITH THE SHIFT VALUE TO SCALE THE OUTPUT ~12 <> ~20 = High <> Low Amplification.

if (FSignal >= Peak && Pulse == false){  // heart beat causes ADC readings to surge down in value.  

  Peak = FSignal;                        // finding the moment when the downward pulse starts

  peakTime = sampleCounter;              // recodrd the time to derive HRV. 

}

//  NOW IT'S TIME TO LOOK FOR THE HEART BEAT

if ((sampleCounter %20) == 0){// only look for the beat every 20mS. This clears out alot of high frequency noise.

  if (FSignal < 0 && Pulse == false && timer==1){  // signal surges down in value every time there is a pulse

     Pulse = true;                 // Pulse will stay true as long as pulse signal < 0

     timer=0;

     digitalWrite(13,HIGH);            // pin 13 will stay high as long as pulse signal < 0  

     Fade = 255;                       // set the fade value to highest for fading LED on pin 11 (optional)   

     HRV = peakTime - lastPeakTime;    // measure time between beats

     lastPeakTime = peakTime;          // keep track of time for next pulse

     B = true;                         // set the Quantified Self flag when HRV gets updated. NOT cleared inside this ISR     

     rate += HRV;                      // add to the running total of HRV used to determine heart rate

     beatCounter++;                     // beatCounter times when to calculate bpm by averaging the beat time values

     if (beatCounter == 10){            // derive heart rate every 10 beats. adjust as needed

       rate /= beatCounter;             // averaging time between beats

       BPM = 60000/rate;                // how many beats can fit into a minute?

       beatCounter = 0;                 // reset counter

       rate = 0;                        // reset running total

       QS = true;                       // set Beat flag when BPM gets updated. NOT cleared inside this ISR

     }

                    }

  if (FSignal > 0 && Pulse == true ){    // when the values are going up, it's the time between beats

    digitalWrite(13,LOW);               // so turn off the pin 13 LED

    Pulse = false;                      // reset these variables so we can do it again!

    Peak = 0;    

  }

}