Heart Rate ( Pulse ) Sensor

Heart Rate (Pulse) Sensor Description

A heart rate (pulse) sensor is a device used to measure the heart rate of an individual, providing real-time data typically expressed in beats per minute (BPM). These sensors are commonly used in fitness trackers, medical devices, and wearable technologies aimed at monitoring heart health. The sensor often uses optical technology or electrical sensing to detect pulse changes caused by blood flow through the skin.

Specifications

Here are typical specifications you might find for a heart rate (pulse) sensor:

• Sensor Type: Generally optical (using photoplethysmography) or electrical (ECG-type sensors).
• Measurement Range: Typically 30 to 240 BPM (varies by model).
• Accuracy: ±2 BPM or better, depending on sensor type and conditions.
• Interface: I2C, UART, or analog output.
• Operating Voltage: 3.3V to 5V DC (check specific model).
• Current Consumption: Usually around 50 µA to 100 mA (varies between operation and sleep modes).
• Measurement Time: Generally instantaneous or update every second.
• Size: Varies depending on the design, with many sensors being compact to fit in wearable devices.
• Temperature Range: -10°C to 50°C or more (varies based on the model).
• Compatibility: Often compatible with microcontrollers like Arduino and Raspberry Pi.

Example Code to Read Heart Rate Sensor Data

Below, you will find an example of how to use a heart rate (pulse) sensor with an Arduino microcontroller. We’ll assume the use of a common pulse sensor, such as the Pulse Sensor Amped, which interfaces via analog output.

Required Components:

• 1 x Arduino board (e.g., Arduino Uno)
• 1 x Heart Rate (Pulse) Sensor (e.g., Pulse Sensor Amped)
• Jumper wires
• Breadboard (optional)

Connection Diagram:

• Sensor VCC: Connect to 5V on Arduino
• Sensor GND: Connect to GND on Arduino
• Sensor Output (SIG): Connect to an analog pin on the Arduino (e.g., A0)

Arduino Code

Here is a simple example code to read the pulse sensor data and display the heart rate on the serial monitor:

Copy// Define the analog input pin for the pulse sensor
const int pulsePin = A0; 

// Variables to hold sensor readings
int pulseValue;
int threshold = 512; // Threshold value for detecting heartbeat
int heartRate; 
int lastBeatTime = 0; // Last time the sensor detected a beat
int beatCount = 0; // Count of beats detected

void setup() {
    Serial.begin(9600);  // Start serial communication
    pinMode(pulsePin, INPUT);  // Set the pulse pin as input
}

void loop() {
    pulseValue = analogRead(pulsePin); // Read the pulse sensor value

    // Check if pulseValue exceeds the threshold (indicating a heartbeat)
    if (pulseValue > threshold) {
        // Only count the beat if enough time has elapsed since the last detected beat
        if (millis() - lastBeatTime > 1000) { // 1 second debounce
            heartRate = beatCount; // Save the current heart rate
            beatCount = 0; // Reset the beat count for the next interval
            lastBeatTime = millis(); // Update the last beat time
        }
        beatCount++; // Increment beat count
    }

    // Output the current heart rate to the serial monitor
    if (millis() - lastBeatTime >= 1000) { // Update the heart rate every second
        Serial.print("Heart Rate: ");
        Serial.print(heartRate);
        Serial.println(" BPM");
    }

    delay(10); // Short delay for stability
}

Explanation of the Code:

• Pulse Pin Configuration: The pulse sensor is connected to one of the analog pins (A0) on the Arduino.
• Loop Operation: In the loop(), the code continuously reads the value from the pulse sensor.
• Heartbeat Detection: When the sensor value exceeds a defined threshold (indicating a heartbeat), the code checks whether enough time has passed since the last detected beat to avoid counting noise.
• Heart Rate Calculation: The heart rate is calculated every second, based on the count of detected beats in that period.
• Serial Output: The heart rate in BPM is printed to the serial monitor for monitoring.

Conclusion

This example provides a basic foundation for utilizing a heart rate (pulse) sensor with an Arduino. The code can be tailored for various applications, including fitness tracking, health monitoring, or integration into wearable technology. For best results, make sure to calibrate the threshold and test the sensor under real conditions. Always refer to specific sensor documentation for precise wiring and usage guidelines.