Buenas, estoy haciendo un dispositivo que integra varios sensores, y uno de ellos es un pulsometro.
El caso es que funciona perfectamente cuando uso el serialplotter (se ve una señal que claramente coincide con al de mi pulso).
Use un sketch que el dato bruto que recibe arduino lo saca por puerto serial y las BPM por una pantalla led. Y hasta aquí todo correcto, valores sensatos, correlación entre las BPM cuando aguanto la respiración etc etc.
El gran problema es que cuando pretendo que esa salida sea el monitor seria, me da valores muy raros, y hasta donde yo se la salida no debería condicionar para nada el valor de una variable., Adjunto sketch (que codifiqué para mi proyecto), a ver si alguien pudiese decirme donde está el fallo:
#include <Brain.h>
#include <SoftwareSerial.h>
SoftwareSerial mySerial(8, 9);
int pulsePin = 0;
volatile int BPM;
volatile int Signal;
volatile int IBI = 600;
volatile boolean Pulse = false;
volatile boolean QS = false;
const int GSR=A2;
int sensorValue;
Brain brain(Serial);
void setup(){
mySerial.begin(9600);
Serial.begin(9600); // Puerto serial configurado a 9600 Baudios
interruptSetup();
sensorValue=analogRead(GSR);
long sum=0;
sum += sensorValue;
}
void loop(){
int pulso = analogRead(A0);
sensorValue=analogRead(GSR);
if (brain.update()) {
mySerial.println(brain.readErrors());
mySerial.println(brain.readCSV());
mySerial.print("BPM = ");
mySerial.println(BPM);
mySerial.print("Pulso = ");
mySerial.println(pulso);
mySerial.print("sensorValue=");
mySerial.println(sensorValue);
}
if (QS == true){
QS = false;
}
}
El programa tiene una clase llamada Interrupt:
volatile int rate[10]; // array to hold last ten IBI values
volatile unsigned long sampleCounter = 0; // used to determine pulse timing
volatile unsigned long lastBeatTime = 0; // used to find IBI
volatile int P =512; // used to find peak in pulse wave, seeded
volatile int T = 512; // used to find trough in pulse wave, seeded
volatile int thresh = 512; // used to find instant moment of heart beat, seeded
volatile int amp = 100; // used to hold amplitude of pulse waveform, seeded
volatile boolean firstBeat = true; // used to seed rate array so we startup with reasonable BPM
volatile boolean secondBeat = false; // used to seed rate array so we startup with reasonable BPM
void interruptSetup(){
// Initializes Timer2 to throw an interrupt every 2mS.
TCCR2A = 0x02; // DISABLE PWM ON DIGITAL PINS 3 AND 11, AND GO INTO CTC MODE
TCCR2B = 0x06; // DON'T FORCE COMPARE, 256 PRESCALER
OCR2A = 0X7C; // SET THE TOP OF THE COUNT TO 124 FOR 500Hz SAMPLE RATE
TIMSK2 = 0x02; // ENABLE INTERRUPT ON MATCH BETWEEN TIMER2 AND OCR2A
sei(); // MAKE SURE GLOBAL INTERRUPTS ARE ENABLED
}
// THIS IS THE TIMER 2 INTERRUPT SERVICE ROUTINE.
// Timer 2 makes sure that we take a reading every 2 miliseconds
ISR(TIMER2_COMPA_vect){ // triggered when Timer2 counts to 124
cli(); // disable interrupts while we do this
Signal = analogRead(pulsePin); // read the Pulse Sensor
sampleCounter += 2; // keep track of the time in mS with this variable
int 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
IBI = sampleCounter - lastBeatTime; // measure time between beats in mS
lastBeatTime = sampleCounter; // keep track of time for next pulse
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;
}
}
if(firstBeat){ // if it's the first time we found a beat, if firstBeat == TRUE
firstBeat = false; // clear firstBeat flag
secondBeat = true; // set the second beat flag
sei(); // enable interrupts again
return; // IBI value is unreliable so discard it
}
// keep a running total of the last 10 IBI values
word 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!
QS = true; // set Quantified Self flag
// QS FLAG IS NOT CLEARED INSIDE THIS ISR
}
}
if (Signal < thresh && Pulse == true){ // when the values are going down, the beat is over
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 = 512; // 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 = false; // when we get the heartbeat back
}
sei(); // enable interrupts when youre done!
}// end isr
Ya probé a variar el valor del threshold adapatándolo a los valores de mi señal, pero la respuesta es la misma.
También probé un sketch mas sencillo, pero no entiendo por que no funciona, también da valores sin sentido y el pulsometro funciona perfectamente:
int pulso = 0, BPM;
unsigned long tiempo1=0, tiempo2 = 0,tiempotranscurrido = 0;
void setup(){
Serial.begin(9600);
pinMode(A0,INPUT);
}
void loop() {
pulso = analogRead(A0);
if (pulso >= 360){
tiempo2 = millis();
tiempotranscurrido= tiempo2-tiempo1;
tiempo1 = tiempo2;
delay (100);
}
BPM = 60*(tiempotranscurrido/1000);
//Serial.println(BPM);
Serial.println(pulso);
delay(50);
}
Si me pudiesen echar un cable con cualquiera de los dos códigos, lo agradecería muchísimo, un saludo!