Hi,
I want to log HR, Gyro and Accelerometer data during sleep to a file and then transfer it later when connected.
I'm getting the data OK it's just the writing to a file I'm struggling with. I've got a button that starts the recording every second and then stops the recording and shows the file stats to the console. I'm opening a file in append mode and want to add each 1 second of data to the file.
When I press the stop button the stats always show 40 bytes written!
The writing to file occurs in the refreshData() function. I think it's got something to do with me not understanding the ArrayBuffer and maybe not converting to binary beforehand? I couldn't find any examples anywhere of how to append data to a file.
import document from "document";
import { Accelerometer } from "accelerometer";
import { HeartRateSensor } from "heart-rate";
import { Gyroscope } from "gyroscope";
import * as fs from "fs";
let thisDate = new Date();
let recFilename = `RawDataLogger-${thisDate.getFullYear()}${("0" + (thisDate.getMonth() + 1)).slice(-2)}${("0" + (thisDate.getDate() + 1)).slice(-2)}.txt`;
console.log(recFilename);
let fileID = 0;
//let buffer = new Uint8Array(8);
let buffer = new ArrayBuffer(8);
let accel = new Accelerometer();
let hrm = new HeartRateSensor();
let gyro = new Gyroscope();
// let accelData = document.getElementById('accel-label');
// let hrmData = document.getElementById('hrm-label');
// let gyroData = document.getElementById('gyro-label');
let btnRecord = document.getElementById('btn-rec');
let recording = false;
let recFunction = null;
btnRecord.onclick = function(evt){
if (recording) {
recording = false;
btnRecord.text = "Record";
// Stop Device Sensors
accel.stop();
hrm.stop();
gyro.stop();
// Cancel the recording function
clearInterval(recFunction);
// Dev Check - Check the stats of the file written
let stats = fs.statSync(fileID);
if (stats) {
console.log("File size: " + stats.size + " bytes");
console.log("Last modified: " + stats.mtime);
}
// Close the file
fs.closeSync(fileID);
} else {
recording = true;
btnRecord.text = "Stop";
// Start Device Sensors
accel.start();
hrm.start();
gyro.start();
// Init the file
fileID = fs.openSync(recFilename, "a+");
// Set callback recording function
recFunction = setInterval(refreshData, 1000);
}
}
function refreshData() {
// Populate ArrayBuffer
buffer[0] = thisDate.getTime();
buffer[1] = hrm.heartRate ? hrm.heartRate : 0;
buffer[2] = accel.x ? accel.x.toFixed(1) : 0;
buffer[3] = accel.y ? accel.y.toFixed(1) : 0;
buffer[4] = accel.z ? accel.z.toFixed(1) : 0;
buffer[5] = gyro.x ? gyro.x.toFixed(1) : 0;
buffer[6] = gyro.y ? gyro.y.toFixed(1) : 0;
buffer[7] = gyro.z ? gyro.z.toFixed(1) : 0;
// Write ArrayBuffer to file
fs.writeSync(fileID, buffer);
}
I could correctly read and write using a readFileSync & writeFileSync but I need to keep appending each set of data which I assume means usig writeSync.
Any help or pointers anybody please?
