Hey Guys,
I'm sort of a newbie to the forum, and to the Arduino board (code managing) as well.
I have been working with the Arduino Uno to complete (for a second time) this project.
I am trying to connect the Pulse Sensor to the Arduino, as well as have the led light up with each heartbeat as well.
I've been pulling out my hair for days trying to find a permutation of coding that works. Initially after I bought the darned sensor -- weeks of code permutations -- I have finally made it working. Some underlying issue with the code was , but I have switched over computers; I have moved; the arduino [somehow] disappeared; I have misplaced the coding.
The code I'm attaching is the bit I'm having trouble with,. I'll supply the entire code in its original format (there are numerous circling the internet). I can't get it work simple and straightforward. Help/Suggestions would be much appreciated.
Thanks in advance.
volatile int rate[10]; // used to get running average of HRV values
volatile unsigned long lastBeatTime = 0; // used to find the time between beats
volatile int sampleCounter; // used to determine pulse timing
volatile int runningTotal; // used to keep track of pulses
volatile boolean firstBeat = true; // used to seed rate array so we startup with reasonable BPM
volatile boolean secondBeat = true; // used to seed rate array so we startup with reasonable BPM
void interruptSetup(){
// Initializes Timer1 to throw an interrupt every 1mS.
TCCR1A = 0x00; // DISABLE OUTPUTS AND 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
}
// THIS IS THE TIMER 1 INTERRUPT SERVICE ROUTINE.
ISR(TIMER1_OVF_vect){ // triggered every time Timer 1 overflows
// Timer 1 makes sure that we take a reading every milisecond
Signal = analogRead(pulsePin); // read the Pulse Sensor
sampleCounter++; // keep track of the time with this variable (ISR triggered every 1mS
// NOW IT'S TIME TO LOOK FOR THE HEART BEAT
int H = sampleCounter-lastBeatTime; // monitor the time since the last beat to avoid noise
if ( (Signal > 520) && (Pulse == false) && (H > 500) ){
// signal surges up in value every time there is a pulse
Pulse = true; // set the Pulse flag when we think there is a pulse
digitalWrite(13,HIGH); // turn on pin 13 LED
HRV = sampleCounter - lastBeatTime; // measure time between beats in mS
lastBeatTime = sampleCounter; // keep track of time for next pulse
if(firstBeat){ // if it's the first time we found a beat
firstBeat = false; // clear firstBeat flag
return; // HRV value is unreliable so discard it
}
if(secondBeat){ // if this is the second beat
secondBeat = false; // clear secondBeat flag
for(int i=0; i<=9; i++){ // seed the running total to get a realisitic BPM at startup
rate[i] = HRV;
}
}
// keep a running total of the last 10 HRV values
for(int i=0; i<=8; i++){
rate[i] = rate[i+1]; // shift data in the rate array and drop the oldest HRV value
}
rate[9] = HRV; // add the latest HRV to the rate array
runningTotal = 0; // clear the runningTotal variable
for(int i=0; i<=9; i++){
runningTotal += rate[i]; // add up the last 10 HRV values
}
runningTotal /= 10; // average the last 10 HRV values
BPM = 60000/runningTotal; // how many beats can fit into a minute? that's BPM!
QS = true; // set Quantified Self flag when beat is found and BPM gets updated.
// QS FLAG IS NOT CLEARED INSIDE THIS ISR
}
if (Signal < 500 && Pulse == true){ // when the values are going down, it's the time between beats
digitalWrite(13,LOW); // turn off pin 13 LED
Pulse = false; // reset the Pulse flag so we can do it again!
}
}
