co2-monitor-hid.js

/*
	
	Receive values from a CO2 Monitor via node-hid
	
	AirControl Mini CO2
	TFA 31.5006
	
	https://hackaday.io/project/5301-reverse-engineering-a-low-cost-usb-co-monitor/log/17909-all-your-base-are-belong-to-us
	
*/

const HID = require('node-hid');

let dev;

try {
	dev = new HID.HID(0x04d9, 0xa052);
} catch (e) {
	console.error('Error: Failed to open device: ' + e.message);
	process.exit(1);
}

dev.sendFeatureReport(Buffer.from([0xc4]));

dev.on('data', (data) => {
	if (
		data[4] !== 0x0d ||
		((data[0] + data[1] + data[2]) & 0xff) !== data[3]
	) {
		console.error('Error: Checksum error.');
		return;
	}
	
	switch (data[0]) {
		case 80:
			console.log('CO2: ', data.readInt16BE(1));
			break;
		case 66:
			console.log('Temp: ', (data.readInt16BE(1) / 16.0 - 273.15).toFixed(3));
			break;
	}
});

dev.on('error', (error) => {
	console.error('Error: ', error);
});