macchina.io EDGE - Ruuvi Tag MQTT Message Decoding

macchina-ruuvi-mqtt.js

function mac2string(mac)
{
    var result = '';
    for (var i = 0; i < mac.length; i++)
    {
        if (i > 0) result += ':';
        result += mac[i].toString(16).padStart(2, '0');
    }
    return result;
}

var mqttClientRefs = serviceRegistry.find(`io.macchina.mqtt.id == "appinf"`);
var mqttClient;
if (mqttClientRefs.length > 0)
{
    mqttClient = mqttClientRefs[0].instance();

    mqttClient.on('messageArrived', ev => {
        const payloadString = ev.data.message.payload;
        const payloadObject = JSON.parse(payloadString);
        const data = payloadObject.data;
        if (data)
        {
            const buffer = new Buffer(data, 'HEXBIN');
            if (buffer[4] === 0xFF && buffer[5] === 0x99 && buffer[6] === 0x04)
            {
                // RUUVI advertisement
                if (buffer[7] === 0x05)
                {
                    // Data format 5 (RAWv2)
                    const payload = buffer.slice(7);
                    const values = payload.unpack('!BhHHhhhH');
                    const temperature = values[1]*0.005;
                    const humidity = values[2]*0.0025;
                    const pressure = (values[3]+50000)/100;
                    const voltage = (((values[7] >> 5) & 0x7ff) + 1600.0)/1000.0;
                    const mac = mac2string(payload.slice(18, 24));

                    console.log('temp=%f hum=%f press=%f voltage=%f, mac=%s', temperature, humidity, pressure, voltage, mac);
                }
            }
        }
    });

    mqttClient.subscribe('ruuvi/#', 0);
}