sgp30

Overview

The sgp30 node reads air quality data from the Sensirion SGP30 multi-pixel gas sensor via I2C. It provides equivalent CO2, Total VOC, raw hydrogen, and raw ethanol measurements. The SGP30 features on-chip humidity compensation and baseline management for long-term stability in smart ventilation and air quality systems.

Wiring (I2C)

Properties

Output

{
  "payload": {
    "eCO2": 520,
    "TVOC": 18,
    "H2": 13243,
    "ethanol": 18745
  },
  "eCO2": 520,
  "TVOC": 18,
  "rawH2": 13243,
  "rawEthanol": 18745,
  "timestamp": 1640000000000
}

Example: Smart Ventilation Control

Automatically control exhaust fans and fresh air intake based on real-time air quality readings.

// Function node: Ventilation speed controller
var eCO2 = msg.eCO2;
var tvoc = msg.TVOC;

// Fan speed zones (PWM 0-100%)
var fanSpeed = 0;

if (eCO2 > 2000 || tvoc > 500) {
    fanSpeed = 100; // Maximum ventilation
} else if (eCO2 > 1200 || tvoc > 200) {
    fanSpeed = 75;  // High
} else if (eCO2 > 800 || tvoc > 100) {
    fanSpeed = 50;  // Medium
} else if (eCO2 > 600) {
    fanSpeed = 25;  // Low
}

// Gradual transitions to avoid sudden changes
var current = flow.get('fanSpeed') || 0;
var step = 5;
if (fanSpeed > current) {
    current = Math.min(fanSpeed, current + step);
} else if (fanSpeed < current) {
    current = Math.max(fanSpeed, current - step);
}
flow.set('fanSpeed', current);

msg.payload = {
    eCO2: eCO2,
    tvoc: tvoc,
    fanSpeed: current,
    mode: current === 0 ? "off" : "running"
};

return msg;

Example: Baseline Persistence

Save and restore the sensor baseline to maintain calibration accuracy across reboots.

// Function node: Save baseline every hour
var baseline = msg.baseline;
var lastSave = flow.get('lastBaselineSave') || 0;
var now = Date.now();

// Save baseline every hour after 12h initial period
var uptime = flow.get('sensorUptime') || now;
var runHours = (now - uptime) / 3600000;

if (runHours > 12 && (now - lastSave) > 3600000) {
    flow.set('lastBaselineSave', now);

    // Store to persistent context
    global.set('sgp30_baseline', {
        eCO2: baseline.eCO2,
        TVOC: baseline.TVOC,
        savedAt: now
    });

    msg.payload = "Baseline saved: " + JSON.stringify(baseline);
    return msg;
}

return null;

Use Cases