Heartbeat Sensor using Arduino (Heart Rate Monitor)
In this post we are going to make a Heart Beat Detection and Monitoring System using Arduino that will detect the heart beat using the Pulse Sensor and will display the reading in 16×2 LCD in BPM (Beats Per Minute).
The Heartbeat Sensor
Heartbeat Sensor is an electronic device that is used to measure the heart rate i.e. speed of the heartbeat. Monitoring body temperature, heart rate and blood pressure are the basic things that we do in order to keep us healthy.
Heart Rate can be monitored in two ways: one way is to manually check the pulse either at wrists or neck and the other way is to use a Heartbeat Sensor
The principle behind the working of the Heartbeat Sensor is Photoplethysmograph. According to this principle, the changes in the volume of blood in an organ is measured by the changes in the intensity of the light passing through that organ.
Working of Heartbeat Sensor
A simple Heartbeat Sensor consists of a sensor and a control circuit. The sensor part of the Heartbeat Sensor consists of an IR LED and a Photo Diode placed in a clip.
The sensor has a clip to insert the finger and has three pins coming out of it for connecting VCC, GND and the Data.
Parts needed:
So, for this example, you’ll need:
- Arduino UNO x 1
- 16 x 2 LCD Display x 1
- 10KΩ Potentiometer
- Heartbeat Sensor Module (finger based)
- Bread Board.
- Jumper Wires.
Circuit Design of Interfacing Heartbeat Sensor with Arduino
First we connect heartbeat sensor with arduino and display readings in the serial monitor.then we connect a 16×2 LCD display to show the readings.
Pin Wiring
Wiring your sensor to the Arduino is pretty simple:
Pin | Wiring to Arduino Uno |
A0 | Analog Pins |
GND | GND |
VCC | 5V |
Schematics
Follow these schematics to complete the project:
Code
Upload the following sketch to your Arduino board:
//code copied from arduino.cc
int pulsePin = A0; // Pulse Sensor purple wire connected to analog pin A0
int blinkPin = 13; // pin to blink led at each beat
// 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.
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!
Serial.begin(115200); // we agree to talk fast!
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
serialOutputWhenBeatHappens(); // A Beat Happened, Output that to serial.
QS = false; // reset the Quantified Self flag for next time
}
delay(20); // take a break
}
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
{
Serial.print(" Heart-Beat Found "); //ASCII Art Madness
Serial.print("BPM: ");
Serial.println(BPM);
}
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:
}
void sendDataToSerial(char symbol, int data )
{
Serial.print(symbol);
Serial.println(data);
}
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
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(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
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 = 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
After uploading the code open serial monitor at 115200 baud rate,
and put your fingure at the heartbeat sensor module.
you will see your heartbeat in BPM.
*For adults 18 and older, a normal resting heart rate is between 60 and 100 beats per minute (bpm), depending on the person’s physical condition and age. For children ages 6 to 15, the normal resting heart rate is between 70 and 100 bpm, according to the AHA
Displaying result in 16×2 LCD Display.
This time I am going to display the readings of heartbeat sensor in 16×2 LCD display ,
The connection of heartbeat sensor with arduino is same ,just you have to connect the 16×2 LCD display to the arduino as the given circuit diagram below.
Code
Upload the following sketch to your Arduino board:
#include <LiquidCrystal.h>
const int rs = 12, en = 11, d4 = 5, d5 = 4, d6 = 3, d7 = 2;
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
int pulsePin = A0; // Pulse Sensor purple wire connected to analog pin A0
int blinkPin = 13; // pin to blink led at each beat
// 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.
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!
Serial.begin(115200); // we agree to talk fast!
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);
lcd.begin(16, 2);
lcd.clear();
}
// 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
serialOutputWhenBeatHappens(); // A Beat Happened, Output that to serial.
QS = false; // reset the Quantified Self flag for next time
}
delay(20); // take a break
}
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
{
Serial.print(" Heart-Beat Found "); //ASCII Art Madness
Serial.print("BPM: ");
Serial.println(BPM);
lcd.print("Heart-Beat Found ");
lcd.setCursor(1,1);
lcd.print("BPM: ");
lcd.setCursor(5,1);
lcd.print(BPM);
delay(300);
lcd.clear();
}
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:
}
void sendDataToSerial(char symbol, int data )
{
Serial.print(symbol);
Serial.println(data);
}
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
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(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
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 = 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
After uploading the code again put your any fingure on heartbeat sensor.
Video demonstration
Watch this quick video demonstration to see this project in action:
I hope you found this post useful.
Share this post with a friend that also likes electronics!
Post Views: 24,949
Thank you, for this code and it is working correctly, but can you please share the code for interfacing pulse rate sensor with NodeMCU?
Thank you once again
Okay I will share the code for interfacing pulse rate sensor with NODEMCU.
Thank you, sir can you please share the code for interfacing pulse sensor
Thank you once again
hey can you send code to me too? ryanshrestha0419@gmail.com thank you.
Check Your Mail
it isn’t showing the output
Error while setting serial port parameters: 115,200 N 8 1
what to do now?
Set Correct Baud rate.
we ordered 16×2 display from amazon but not able to hook up the jumper cables on the back. which specific 16×2 display did you use?
First Soldire headers on the back of LCD.
Showing a garbage value
When sensor is not attached …..it is normal to show garbage value.
yes it is normal
Code is good but without giving the data it is showing the output. Can u please give me reply for this.
If the sensor is not attached with any of the fingure, it will gives garbage value …….its normal
Does this code working by writing it directly in the Arduino software or do we have to install some other modules? Please reply as soon as you can.
please share nodemcu code ,thanks alot.
EMAIL:-aftaabjariwala@gmail.co,
Hello sir, may I have the code for Nodemcu ESP32 too?
Can you email me at: unsungtraveller@gmail.com
Ok sure
Hi sir in materials required there is mentioned switch but its not used in this right as it is not used here could you send the code with switch to this mail teritemp2@gmail.com
Hello, Well Done man!!!
Can you please give the code for using TM1637 instead of LCD with the same task (just displaying the BPM only)?
Wow ccuz this iis great work! Congrats and keep it up!
Your tutorial is really amazing, can you please give me this code for ESP32 dev board.
My mail ID is manaaz2111@gmail.com
Yes Sure.
Thank You, It is working so well. can you please send me the code for nodemcu
mail: 10kdreddy@gmail.com
will upload video soon.
sir, can you share the code for interfacing pulse rate sensor with NODEMCU.
thank you.
mail id:- randyrock049@gmail.com
Hello and thank you for sharing this project! May i ask if the Antistatic Bag is needed for the sensor? Can i place something else behind it?
Put anything except metal.
Hey bro… If u dont mind then can i get code for pulse sensor temperature sensor and heart sensor… We have project sir said use 3 sensor along with ur ventilator project… I’m just confused how to merge this all code.. If u dont mind can u help me
To be honest Very very useful projects..nd detailed explanation sir.. thank u so much
Good, can you send code to me too? bammyoc@gmail.com thank you
bro can you send code after installing breadboard,Arduino and jumper wires my email id bhukyayashodhara@gamil.com
OK sure
Could you please send me the code?
ayansheikh252550@gmail.com
:\Users\ROHAN\Music\heartsensor\hearttsensor\hearttsensor.ino: In function ‘void setup()’:
C:\Users\ROHAN\Music\heartsensor\hearttsensor\hearttsensor.ino:26:1: error: a function-definition is not allowed here before ‘{‘ token
{
^
C:\Users\ROHAN\Music\heartsensor\hearttsensor\hearttsensor.ino:38:1: error: a function-definition is not allowed here before ‘{‘ token
{
^
C:\Users\ROHAN\Music\heartsensor\hearttsensor\hearttsensor.ino:54:1: error: a function-definition is not allowed here before ‘{‘ token
{
^
C:\Users\ROHAN\Music\heartsensor\hearttsensor\hearttsensor.ino:64:1: error: a function-definition is not allowed here before ‘{‘ token
{ // Decide How To Output Serial.
^
C:\Users\ROHAN\Music\heartsensor\hearttsensor\hearttsensor.ino:76:1: error: a function-definition is not allowed here before ‘{‘ token
{
^
C:\Users\ROHAN\Music\heartsensor\hearttsensor\hearttsensor.ino:91:1: error: a function-definition is not allowed here before ‘{‘ token
{
^
C:\Users\ROHAN\Music\heartsensor\hearttsensor\hearttsensor.ino:102:1: error: a function-definition is not allowed here before ‘{‘ token
{
^
In file included from C:\Users\ROHAN\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.8.5\cores\arduino/Arduino.h:30:0,
from C:\Users\ROHAN\AppData\Local\Temp\arduino-sketch-33EAFD52DEFD8C3D9199720CED8D6EA8\sketch\hearttsensor.ino.cpp:1:
C:\Users\ROHAN\Music\heartsensor\hearttsensor\hearttsensor.ino:107:1: error: expected unqualified-id before string constant
ISR(TIMER2_COMPA_vect) //triggered when Timer2 counts to 124
^
C:\Users\ROHAN\Music\heartsensor\hearttsensor\hearttsensor.ino:108:1: error: a function-definition is not allowed here before ‘{‘ token
{
^
Compilation error: exit status 1
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