Dear Arduino community,
I am working on a project and I have the next issue: As you can see in the code, when I am inserting into the Serial Monitor two different values, one for "pulsbreite" and one for "pulsbreite1" working with the LED ("ledgelb"), the heartbeat-values are not stable. They are going up and down and will not display the correct heartbeat value. I am using a heartbeat sensor from PulseSensor.com
Can someone help me with this issue? Is it better to create an Interrupt with the following code:
digitalWrite(ledgelb, HIGH);
delay(pulsbreite);
digitalWrite(ledgelb, LOW);
delay(pulsbreite1);
Serial.print(Zeit1);
Serial.println(" ms");
Serial.print(BPM);
Serial.println("Hz");
Serial.print(pulsbreite);
Serial.println(" ms");
Serial.print(pulsbreite1);
Serial.println(" ms");
Serial.println("\n");
return BPM;
Here is the whole code:
#include <Wire.h>
#include <math.h>
#include "rgb_lcd.h"
#include "PWM.h"
volatile int rate[10];
volatile unsigned long sampleCounter = 0;
volatile unsigned long lastBeatTime = 0;
volatile int P = 512;
volatile int T = 512;
volatile int thresh = 525;
volatile int amp = 100;
volatile boolean firstBeat = true;
volatile boolean secondBeat = true;
word runningTotal;
int blinkPin = 13;
int AnalogPin = 0;
int IBI = 600;
int Pulse = false;
int Signal;
float Rwert;
volatile unsigned long Zeit1;
const int ledrot = 13;
const int ledgelb = 12;
const int ledgruen = 11;
int BPM;
int BPM1 = 60;
int testzeit;
int pulsbreite;
int pulsbreite1;
int N;
void setup() {
Serial.begin(9600);
pinMode(ledrot, OUTPUT);
pinMode(ledgelb, OUTPUT);
pinMode(ledgruen, OUTPUT);
Serial.println("<Arduino is ready>");
delay(1000);
}
void loop() {
Rwert = ((Signal * 5.0) / 1023) * 1000;
testzeit = (60000 / BPM1);
if (Serial.available() > 0) {
pulsbreite = Serial.parseInt();
pulsbreite1 = Serial.parseInt();
if (Serial.read() == '\n') {
}
}
cli(); // disable interrupts while we do this
Signal = analogRead(AnalogPin); // read the Pulse Sensor
sampleCounter += 2; // keep track of the time in mS with this variable
N = sampleCounter - lastBeatTime; // monitor the time since the last beat to avoid noise
// find the peak and trough of the pulse wave
if (Signal < thresh && N > (IBI / 5) * 3) { // avoid dichrotic noise by waiting 3/5 of last IBI
if (Signal < T) { // T is the trough
T = Signal; // keep track of lowest point in pulse wave
}
}
if (Signal > thresh && Signal > P) { // thresh condition helps avoid noise
P = Signal; // P is the peak
} // keep track of highest point in pulse wave
// NOW IT'S TIME TO LOOK FOR THE HEART BEAT
// signal surges up in value every time there is a pulse
if (N > 250) { // avoid high frequency noise
if ( (Signal > thresh) && (Pulse == false) && (N > (IBI / 5) * 3) ) {
Pulse = true; // set the Pulse flag when we think there is a pulse
digitalWrite(blinkPin, HIGH); // turn on pin 13 LED
IBI = 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, if firstBeat == TRUE
firstBeat = false; // clear firstBeat flag
return; // IBI value is unreliable so discard it
}
if (secondBeat) { // if this is the second beat, if secondBeat == TRUE
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] = IBI;
}
}
// keep a running total of the last 10 IBI values
runningTotal = 0; // clear the runningTotal variable
for (int i = 0; i <= 8; i++) { // shift data in the rate array
rate[i] = rate[i + 1]; // and drop the oldest IBI value
runningTotal += rate[i]; // add up the 9 oldest IBI values
}
rate[9] = IBI; // add the latest IBI to the rate array
runningTotal += rate[9]; // add the latest IBI to runningTotal
runningTotal /= 10; // average the last 10 IBI values
BPM = 60000 / runningTotal; // how many beats can fit into a minute? that's BPM!
int QS = true; // set Quantified Self flag
// QS FLAG IS NOT CLEARED INSIDE THIS ISR
Zeit1 = (runningTotal - ((0.1) * runningTotal));
digitalWrite(ledrot, HIGH);
Serial.print(BPM);
Serial.println(" Hz");
Serial.print(runningTotal);
Serial.println(" ms");
Serial.print(Rwert);
Serial.println(" mV");
Serial.print(Zeit1);
Serial.println(" ms");
Serial.print(BPM1);
Serial.println(" Hz");
Serial.print(testzeit);
Serial.println(" ms");
Serial.print("\n");
digitalWrite(ledrot, LOW);
if (Zeit1 < testzeit) {
sei();
digitalWrite(ledgelb, HIGH);
delay(pulsbreite);
digitalWrite(ledgelb, LOW);
delay(pulsbreite1);
Serial.print(Zeit1);
Serial.println(" ms");
Serial.print(BPM);
Serial.println("Hz");
Serial.print(pulsbreite);
Serial.println(" ms");
Serial.print(pulsbreite1);
Serial.println(" ms");
Serial.println("\n");
return BPM;
cli();
}
}
}
if (Signal > thresh && Pulse == true) { // when the values are going down, the beat is over
digitalWrite(blinkPin, LOW); // turn off pin 13 LED
Pulse = false; // reset the Pulse flag so we can do it again
amp = P - T; // get amplitude of the pulse wave
thresh = amp / 2 + T; // set thresh at 50% of the amplitude
P = thresh; // reset these for next time
T = thresh;
}
if (N > 2500) { // if 2.5 seconds go by without a beat
thresh = 525; // set thresh default
P = 512; // set P default
T = 512; // set T default
lastBeatTime = sampleCounter; // bring the lastBeatTime up to date
firstBeat = true; // set these to avoid noise
secondBeat = true; // when we get the heartbeat back
}
delay(60);
sei(); // enable interrupts when youre done!
}
Thank you very much in advance
Best regards
Kosta
