Inconsistent Heart Rate Monitoring Values from Human Activity Monitor

Original Created Apr 12, 2016 | Regeneration Apr 22, 2026

Question

I'm trying to retrieve heart rate data using the Human Activity Monitor's HRM functionality with the following code:

var HRUtils = {
    abc: function() {
        var count = 0;
        
        function onsuccessCB(heartInfo) {
            console.log("Rate: " + heartInfo.heartRate);
            
            count++;
            if(count >= 100) {
                tizen.humanactivitymonitor.stop("HRM");
            }
        }

        function onerrorCB(error) {
            alert("Error!");
        }

        function onchangedCB(heartData) {
            tizen.humanactivitymonitor.getHumanActivityData("HRM", onsuccessCB, onerrorCB);
        }

        tizen.humanactivitymonitor.start("HRM", onchangedCB);
    }
};

The code works intermittently - sometimes it returns correct values (75, 73, 74... 80) but other times it returns all zeros (0, 0, 0, 0...). I can't determine why this inconsistency occurs.

Answer

Problem Understanding

The issue appears to be related to the HRM sensor's initialization and stabilization period. The inconsistent readings (correct values vs. zeros) suggest:

The sensor needs time to stabilize and get accurate readings
The device (like Gear S2) needs to be properly fitted on the wrist
There might be initialization timing issues in the code

Solution Methods

Allow Sensor Stabilization Time:
- Wait 5-10 seconds after starting the HRM before expecting accurate readings
- Implement a delay mechanism or initial warm-up period
Check Device Fit:
- Ensure the wearable device is properly fitted on the wrist
- Make sure the sensor area has good contact with skin
Review Sample Code:
- Examine the official HeartRateMonitor sample app in Tizen IDE
- Consider using the TizenBeat open-source project as reference

Code Examples

Here's an improved version of the code with stabilization handling:

var HRUtils = {
    monitorHeartRate: function() {
        var count = 0;
        var isStabilized = false;
        var stabilizationTimer = null;

        function onsuccessCB(heartInfo) {
            if (isStabilized) {
                console.log("Rate: " + heartInfo.heartRate);
                count++;
                
                if(count >= 100) {
                    tizen.humanactivitymonitor.stop("HRM");
                    clearTimeout(stabilizationTimer);
                }
            }
        }

        function onerrorCB(error) {
            console.error("HRM Error: " + error.message);
        }

        function onchangedCB(heartData) {
            tizen.humanactivitymonitor.getHumanActivityData("HRM", onsuccessCB, onerrorCB);
        }

        tizen.humanactivitymonitor.start("HRM", onchangedCB);
        
        // Allow 5 seconds for sensor stabilization
        stabilizationTimer = setTimeout(function() {
            isStabilized = true;
            console.log("Sensor stabilized - beginning data collection");
        }, 5000);
    }
};

Additional Tips

For reference implementations:
- Access the HeartRateMonitor sample in Tizen IDE: File → New → Tizen Web Project → Online Sample → HeartRateMonitor
- Check the TizenBeat project: https://github.com/alycecil/TizenBeat
Remember that HRM sensors:
- Work best when the user remains still during measurement
- May require periodic recalibration
- Performance can vary based on skin type and environmental conditions