Grove - Ear-clip Heart Rate Sensor

Introduction

3.3V 5.0V Digital

The Heart Rate Ear clip kit contains a ear clip and a receiver module. The heart rate measure kit can be used to monitor heart rate of patient and athlete. The result can be displayed on a screen via the serial port and can be saved for analysis. The entire system is a high sensitivity, low power consumption and portable.

Features

  • Low power consumption
  • Convenient to use
  • High sensitivity
  • Fully RoHS compliant

Tip

More details about Grove modules please refer to Grove System

Specifications

Item Min Typical Max Unit
Voltage 3.0 5.0 5.25 V
Work Current 6.5 mA
Length of ear clip wire 120 cm
Measures Range ≥30/min -

Application Ideas

  • Heart rate monitor.

Platforms Supported

Usage

The following sketch demonstrates a simple application of using the Ear-clip Heart Rate Sensor to measure heart rate.

  • Connect this module to the digital port D2 on Grove-Base shield. And connect Grove-LED to Digital port 4.
  • Plug the Base Shield into Arduino/Seeeduino.

  • Copy and paste code below to a new Arduino sketch.
    // Function: This program can be used to measure heart rate, the lowest pulse in the program be set to 30.
    //         Use an external interrupt to measure it.
    // Hardware: Grove - Ear-clip Heart Rate Sensor, Grove - Base Shield, Grove - LED
    // Arduino IDE: Arduino-1.0
    // Author: FrankieChu       
    // Date: Jan 22, 2013
    // Version: v1.0
    // by www.seeedstudio.com
    #define LED 4//indicator, Grove - LED is connected with D4 of Arduino
    boolean led_state = LOW;//state of LED, each time an external interrupt 
                                    //will change the state of LED
    unsigned char counter;
    unsigned long temp[21];
    unsigned long sub;
    bool data_effect=true;
    unsigned int heart_rate;//the measurement result of heart rate

    const int max_heartpluse_duty = 2000;//you can change it follow your system's request.
                            //2000 meams 2 seconds. System return error 
                            //if the duty overtrip 2 second.
    void setup()
    {
        pinMode(LED, OUTPUT);
        Serial.begin(9600);
        Serial.println("Please ready your chest belt.");
        delay(5000);
        arrayInit();
        Serial.println("Heart rate test begin.");
        attachInterrupt(0, interrupt, RISING);//set interrupt 0,digital port 2
    }
    void loop()
    {
        digitalWrite(LED, led_state);//Update the state of the indicator
    }
    /*Function: calculate the heart rate*/
    void sum()
    {
     if(data_effect)
        {
          heart_rate=1200000/(temp[20]-temp[0]);//60*20*1000/20_total_time 
          Serial.print("Heart_rate_is:\t");
          Serial.println(heart_rate);
        }
       data_effect=1;//sign bit
    }
    /*Function: Interrupt service routine.Get the sigal from the external interrupt*/
    void interrupt()
    {
        temp[counter]=millis();
        Serial.println(counter,DEC);
        Serial.println(temp[counter]);
        switch(counter)
        {
            case 0:
                sub=temp[counter]-temp[20];
                Serial.println(sub);
                break;
            default:
                sub=temp[counter]-temp[counter-1];
                Serial.println(sub);
                break;
        }
        if(sub>max_heartpluse_duty)//set 2 seconds as max heart pluse duty
        {
            data_effect=0;//sign bit
            counter=0;
            Serial.println("Heart rate measure error,test will restart!" );
            arrayInit();
        }
        if (counter==20&&data_effect)
        {
            counter=0;
            sum();
        }
        else if(counter!=20&&data_effect)
        counter++;
        else 
        {
            counter=0;
            data_effect=1;
        }

    }
    /*Function: Initialization for the array(temp)*/
    void arrayInit()
    {
        for(unsigned char i=0;i < 20;i ++)
        {
            temp[i]=0;
        }
        temp[20]=millis();
    }
  • Upload the code.
  • Make sure the sensor contacts your ear skin. This is the signal when we are measuring the heart rate:

In the first of the figures, which is a waveform diagram of the detected heartbeat, a high pulse comes when beating.

Note

If the serial monitor return an error message, please change the position of the sensor.

Resources


ArduinoWioBeagleBoneRaspberry PiLinkIt ONE

Caution

The platforms mentioned above as supported is/are an indication of the module's hardware or theoritical compatibility. We only provide software library or code examples for Arduino platform in most cases. It is not possible to provide software library / demo code for all possible MCU platforms. Hence, users have to write their own software library.

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Happy hacking