Getting Started in monkey C with HRV

Hello,

I am trying to write my first application for my fenix3HR in order to practice programming and creating an application that produces my HRV is of interest. I have experience in Matlab programming, but this is my first time outside that environment. I have read the documentation and tutorials posted on here but I still have some confusion still on how to access and store sensor data of interest.

I am using a modified "sample" code "SimpleDataField" to get me started and I have referenced these links to assist me (API-Doc , GITHUB). Here is what I have so far;

view.mc

using Toybox.WatchUi;
using Toybox.System;
using Toybox.Time;
using Toybox.Sensor;

class DataField extends WatchUi.SimpleDataField {

	var heartBeatIntervals = [];
	
    // Constructor
    function initialize() {
        SimpleDataField.initialize();
        label = "HR";
        counter = 0;
    }

	function compute(sensorData) {
	    if (sensorData has :heartRateData && sensorData.heartRateData != null) {
	         heartBeatIntervals = sensorData.heartRateData.heartBeatIntervals;
	    }
	    return heartBeatIntervals;

	}
}

app.mc

using Toybox.Application;

class SimpleDataField extends Application.AppBase {

    function initialize() {
        AppBase.initialize();
    }

    function onStart(state) {
        return false;
    }

    function getInitialView() {
        return [new DataField()];
    }

    function onStop(state) {
        return false;
    }

}

I would appreciate any insight. Thank you.