So my project requires me to find the voltage peak from the pulse sensor.
2)How can i take the average value of the Voltage peak?
Lets just say,there are 10 peaks in this waveform.
I am using Arduino Uno and Pulse sensor for heart rate.
Really appreciate if anyone can help me out!
Hi all,how can i collect my voltage peak with my sensor?
The attached is the graph from serial plotter.
My requirement in code is to collect the average voltage peak for every 10 seconds or so.
How do i go about this?
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int someHighestValue = 0;
int some NewValue = 0;
if NewValue > someHighestValue then someHighestValue = NewValue.
How can i measure my peak voltage then?
Appreciate your help!
Well, you could hook the signal up to the Analog To Digital converter pin on the Uno, sample the signal and then do the thing.
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mentaikosauceboy:
The attached is the graph from serial plotter.My requirement in code is to collect the average voltage peak for every 10 seconds or so.
How do i go about this?
Have you done anything with the millis() function? There is a lot of information on this site about millis()
So you start a counter of time, add all your readings to a variable, add to another variable the count of readings taken, at the end of the time, divide your totaled readings by the number of readings taken in the time frame allotted.
You need a peak detector circuit that integrates the signal so you can read it with the A/D. Below is a simple one. The capacitor controls how long the sample will survive, the resistor discharges the capacitor. The combination of RC will allow you to adjust the sample to what you want.
There are a lot of on line Peak Detector information. This response is to help you get started in solving your problem, not solve it for you.
Good Luck & Have Fun!
Gil
Hi all thankyou for your kind replies..
I am currently using this code.. How can i go about collecting my max and min vals.. using threshold as I am collecting heart-rate signals/pulse.. and also the MAX and MIN values..!
#include <LiquidCrystal.h>
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
// Variables
int pulsePin = A0;
int blinkPin = 13;
int fadePin = 10;
int fadeRate = 0;
int voltagePeak = 0;
// Volatile Variables, used in the interrupt service routine!
volatile int BPM; // int that holds raw Analog in 0. updated every 2mS
volatile int Signal; // holds the incoming raw data
volatile int IBI = 600; // int that holds the time interval between beats! Must be seeded!
volatile boolean Pulse = false; // "True" when User's live heartbeat is detected. "False" when not a "live beat".
volatile boolean QS = false; // becomes true when Arduoino finds a beat.
// Regards Serial OutPut -- Set This Up to your needs
static boolean serialVisual = true; // Set to 'false' by Default. Re-set to 'true' to see Arduino Serial Monitor ASCII Visual Pulse
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 = 525; // 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 setup()
{
pinMode(blinkPin,OUTPUT); // pin that will blink to your heartbeat!
pinMode(fadePin,OUTPUT); // pin that will fade to your heartbeat!
Serial.begin(115200); // we agree to talk fast!
lcd.begin(16,2);
lcd.print("Extracting...");
lcd.setCursor(0,0);
lcd.print("Extracting...");
interruptSetup(); // sets up to read Pulse Sensor signal every 2mS
// IF YOU ARE POWERING The Pulse Sensor AT VOLTAGE LESS THAN THE BOARD VOLTAGE,
// UN-COMMENT THE NEXT LINE AND APPLY THAT VOLTAGE TO THE A-REF PIN
// analogReference(EXTERNAL);
}
// Where the Magic Happens
void loop()
{
serialOutput();
if (QS == true) // A Heartbeat Was Found
{
// BPM and IBI have been Determined
// Quantified Self "QS" true when arduino finds a heartbeat
fadeRate = 255; // Makes the LED Fade Effect Happen, Set 'fadeRate' Variable to 255 to fade LED with pulse
serialOutputWhenBeatHappens(); // A Beat Happened, Output that to serial.
QS = false; // reset the Quantified Self flag for next time
}
ledFadeToBeat(); // Makes the LED Fade Effect Happen
delay(20); // take a break
}
void ledFadeToBeat()
{
fadeRate -= 15; // set LED fade value
fadeRate = constrain(fadeRate,0,255); // keep LED fade value from going into negative numbers!
analogWrite(fadePin,fadeRate); // fade LED
}
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
}
void serialOutput()
{ // Decide How To Output Serial.
if (serialVisual == true)
{
arduinoSerialMonitorVisual('-', Signal); // goes to function that makes Serial Monitor Visualizer
}
else
{
sendDataToSerial('S', Signal); // goes to sendDataToSerial function
}
}
void serialOutputWhenBeatHappens()
{
if (serialVisual == true) // Code to Make the Serial Monitor Visualizer Work
{
voltagePeak = P;
//Serial.print("*** Heart-Beat Happened *** "); //ASCII Art Madness
Serial.print("BPM: ");
Serial.println(BPM);
//lcd.setCursor (0,1);
Serial.print("Voltage Peak");
Serial.println(voltagePeak);
lcd.setCursor(16,2);
lcd.print("BPM: ");
lcd.println(BPM);
lcd.clear();
lcd.setCursor(0, 1);
lcd.print("Voltage Peak:");
lcd.println(voltagePeak);
}
else
{
sendDataToSerial('B',BPM); // send heart rate with a 'B' prefix
sendDataToSerial('Q',IBI); // send time between beats with a 'Q' prefix
}
}
void arduinoSerialMonitorVisual(char symbol, int data )
{
const int sensorMin = 0; // sensor minimum, discovered through experiment
const int sensorMax = 1024; // sensor maximum, discovered through experiment
int sensorReading = data; // map the sensor range to a range of 12 options:
int range = map(sensorReading, sensorMin, sensorMax, 0, 11);
// do something different depending on the
// range value:
switch (range)
void sendDataToSerial(char symbol, int data )
{
Serial.print(symbol);
Serial.println(data);
}
ISR(TIMER2_COMPA_vect)
{
cli();
Signal = analogRead(pulsePin);
sampleCounter += 2;
int N = sampleCounter - lastBeatTime;
if(Signal < thresh && N > (IBI/5)*3)
{
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;
}
// 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;
digitalWrite(blinkPin,HIGH);
IBI = sampleCounter - lastBeatTime;
lastBeatTime = sampleCounter;
if(secondBeat)
{
secondBeat = false;
for(int i=0; i<=9; i++)
{
rate[i] = IBI;
}
}
if(firstBeat)
{
firstBeat = false;
secondBeat = true;
sei();
return;
}
// keep a running total of the last 10 IBI values
word runningTotal = 0;
for(int i=0; i<=8; i++)
{ // shift data in the rate array
rate[i] = rate[i+1];
runningTotal += rate[i];
}
rate[9] = IBI;
runningTotal += rate[9];
runningTotal /= 10;
BPM = 60000/runningTotal;
QS = true;
// QS FLAG IS NOT CLEARED INSIDE THIS ISR
}
}
if (Signal < thresh && Pulse == true)
{
digitalWrite(blinkPin,LOW);
Pulse = false;
amp = P - T;
thresh = amp/2 + T;
P = thresh;
T = thresh;
}
if (N > 2500)
{
thresh = 512;
P = 512;
T = 512;
lastBeatTime = sampleCounter;
firstBeat = true;
secondBeat = false;
}