A Particulate Matter Detector Using PM 2.5 Sensor by PLANTOWER

particulate-matter.js

//
// http://aqicn.org/air/view/sensor/spec/pms7003.pdf
//

const SerialPort = require('serialport');

const port = new SerialPort('/dev/ttyUSB0', {
    baudRate: 9600
});

port.on('data', (data) => {
    const payload = data.toString('hex');
    const start = payload.slice(0, 4);

    if (start !== '424d') {
        return;
    }

    const frameLength = data.readUInt16BE(2);
    const offset = 4;
    if ((frameLength + offset) < data.length) {
        console.error(`frame length exceeds ${data.length - offset}`);
        return;
    }

    const c0 = data.readUInt16BE(offset + ((frameLength / 2 - 1) << 1));
    const c1 = data.slice(0, -2).reduce((acc, val) => acc + val, 0)
    if (c0 !== c1) {
        console.error('checksum error');
        return;
    }

    // Standard Particles or CF-1, bytes 4-9
    const standardParticles = [
        data.readUInt16BE(offset + ((1 - 1) << 1)), // PM 1.0
        data.readUInt16BE(offset + ((2 - 1) << 1)), // PM 2.5
        data.readUInt16BE(offset + ((3 - 1) << 1)), // PM 10
    ];
    console.log('Standard Particles (CF-1):');
    console.log(`  PM 1.0: ${standardParticles[0]} (ug/m3), PM 2.5: ${standardParticles[1]} (ug/m3), PM 10: ${standardParticles[2]} (ug/m3)`);

    // Atmospheric Environment, bytes 10-15
    const atmosphericEnvironment = [
        data.readUInt16BE(offset + ((4 - 1) << 1)), // PM 1.0
        data.readUInt16BE(offset + ((5 - 1) << 1)), // PM 2.5
        data.readUInt16BE(offset + ((6 - 1) << 1)), // PM 10
    ];
    console.log('Atmosphere Environment:');
    console.log(`  PM 1.0: ${atmosphericEnvironment[0]} (ug/m3), PM 2.5: ${atmosphericEnvironment[1]} (ug/m3), PM 10: ${atmosphericEnvironment[2]} (ug/m3)`);

    // Particles
    if ((frameLength / 2) > 12) {
        const particles = [
            data.readUInt16BE(offset + ((7 - 1) << 1)), // 0.3um
            data.readUInt16BE(offset + ((8 - 1) << 1)), // 0.5um
            data.readUInt16BE(offset + ((9 - 1) << 1)), // 1.0um
            data.readUInt16BE(offset + ((10 - 1) << 1)), // 2.5um
            data.readUInt16BE(offset + ((11 - 1) << 1)), // 5.0um
            data.readUInt16BE(offset + ((12 - 1) << 1)), // 10um
        ];

        console.log('Particles (under 0.1L):');
        console.log(`  * 0.3um: ${particles[0]}`);
        console.log(`  * 0.5um: ${particles[1]}`);
        console.log(`  * 1.0um: ${particles[2]}`);
        console.log(`  * 2.5um: ${particles[3]}`);
        console.log(`  * 5.0um: ${particles[4]}`);
        console.log(`  * 10um: ${particles[5]}`);
    }
});

$ node particulate-matter
Standard Particles (CF-1):
  PM 1.0: 8 (ug/m3), PM 2.5: 8 (ug/m3), PM 10: 8 (ug/m3)
Atmosphere Environment:
  PM 1.0: 8 (ug/m3), PM 2.5: 8 (ug/m3), PM 10: 8 (ug/m3)
Particles (under 0.1L):
  * 0.3um: 1134
  * 0.5um: 362
  * 1.0um: 22
  * 2.5um: 0
  * 5.0um: 0
  * 10um: 0