Smart Meeting Room CO₂ & Comfort Monitor

This project builds a Smart Meeting Room Monitor to check:

CO₂ concentration (air freshness / ventilation quality)

Temperature & humidity (thermal comfort)

Pressure & gas resistance (IAQ indicator)

Light level (is the room in use / correctly lit?)

It combines sensors you already used separately in:

RAK1906 environmental indices:https://www.hackster.io/user2702447/rak1906-air-quality-monitoring-a-focused-guide-on-environme-d2c0d0

RAK1906 + RAK12004 advanced IAQ:https://www.hackster.io/user2702447/advanced-indoor-air-quality-monitoring-rak1906-and-rak12004-e05935

Light + IAQ:https://www.hackster.io/532551/smart-air-quality-and-light-monitoring-system-using-iot-3a3989

Data is sent over LoRaWAN using RAK4631 to The Things Network (TTN) and forwarded via webhook to Ubidots.

Objectives

Build a multi-sensor WisBlock node for meeting room comfort & safety.

Measure CO₂ + IAQ + light + comfort parameters.

Encode values into a compact binary payload.

Use TTN + Ubidots for dashboards and alerts.

Detect poor ventilation (high CO₂), uncomfortable temperature/humidity and inadequate lighting.

Target Level

Intermediate:

Makers, students, educators who already did WisBlock + TTN projects like:https://www.hackster.io/user2702447/getting-started-with-wisblock-and-the-things-network-ttn-0a7b84

Prerequisite Knowledge

Arduino IDE basic usage

I²C sensor basics

LoRaWAN concepts (DevEUI, JoinEUI/AppEUI, AppKey)

Reading Serial Monitor and interpreting sensor data

Required Materials & Software

Hardware

1 × RAK4631 WisBlock Core

1 × RAK19007 WisBlock Base Board

1 × RAK1906 environmental sensor (BME680)

1 × RAK12004 CO₂ sensor (SCD30)

1 × RAK12019 ambient light sensor (BH1750)

1 × LoRaWAN gateway (e.g. WisGate Edge Lite 2)

1 × LoRa antenna

1 × USB-C cable

Optional: enclosure + battery

Software / Online Services

Arduino IDE

WisBlock board support as used in:https://www.hackster.io/user2702447/getting-started-with-wisblock-and-the-things-network-ttn-0a7b84

Libraries:

Adafruit_BME680


SparkFun_SCD30_Arduino_Library (for SCD30 / RAK12004)

BH1750



The Things Network / The Things Stack

Ubidots account

Estimated Duration

About 2–3 hours including hardware, firmware, TTN + Ubidots and dashboard.

Learning Outcomes

Participants will learn to:

Assemble a WisBlock node with RAK1906 + RAK12004 + RAK12019.

Read CO₂, environmental, and light data together.

Encode and decode binary payloads for LoRaWAN.

Integrate TTN with Ubidots using webhook (as in:https://www.hackster.io/user2702447/set-up-ttn-webhooks-integrate-with-ubidots-a-guide-b715d9).

Build dashboards and alerts for healthy meeting rooms.

Steps for Configuration & Implementation

Step 1 – Hardware Assembly

Mount RAK4631 onto RAK19007 base.

Plug RAK1906 into an I²C slot (same style as:https://www.hackster.io/user2702447/rak1906-air-quality-monitoring-a-focused-guide-on-environme-d2c0d0).

Plug RAK12004 (SCD30) into an I²C slot, as in:https://www.hackster.io/user2702447/advanced-indoor-air-quality-monitoring-rak1906-and-rak12004-e05935

Plug RAK12019 into an I²C slot, like:https://www.hackster.io/532551/smart-air-quality-and-light-monitoring-system-using-iot-3a3989

Attach the LoRa antenna.

Connect USB-C to the PC.

Step 2 – Arduino IDE & Boards

Same procedure as your “Getting Started with WisBlock + TTN”:https://www.hackster.io/user2702447/getting-started-with-wisblock-and-the-things-network-ttn-0a7b84

Open Arduino IDE.

Install / confirm WisBlock board support.

Select the RAK4631 board and the correct COM port.

Step 3 – Install Libraries

In Arduino IDE → Sketch → Include Library → Manage Libraries… install:

Adafruit BME680 Library (Adafruit_BME680)

SparkFun SCD30 Arduino Library (SparkFun_SCD30_Arduino_Library)

BH1750 (ambient light sensor driver)

Step 4 – Full Arduino Sketch (Sensors + Payload)

This sketch:

Initializes BME680 (RAK1906), SCD30 (RAK12004), BH1750 (RAK12019)

Reads all sensors

Builds a 16-byte payload

Prints data + payload hex for testing

Is ready to be integrated with your LoRaWAN send code from:https://www.hackster.io/user2702447/getting-started-with-wisblock-and-the-things-network-ttn-0a7b84

#include <Arduino.h>
#include <Wire.h>
#include <Adafruit_BME680.h>
#include <SparkFun_SCD30_Arduino_Library.h>
#include <BH1750.h>

// ---------- Sensor Objects ----------
Adafruit_BME680 bme;      // RAK1906 - BME680
SCD30 airSensor;          // RAK12004 - SCD30
BH1750 lightMeter;        // RAK12019 - BH1750

// Structure for all sensor data
struct SensorData {
  float temp_bme;     // °C
  float hum_bme;      // %RH
  float pressure;     // hPa
  float gas_kOhm;     // kΩ
  float co2;          // ppm
  float temp_scd;     // °C
  float hum_scd;      // %RH
  float lux;          // lux
};

SensorData data;

// -------- Helper functions for encoding ----------
void putInt16(uint8_t *buf, int16_t value, uint8_t index) {
  buf[index]     = (uint8_t)((value >> 8) & 0xFF);
  buf[index + 1] = (uint8_t)(value & 0xFF);
}

void putUInt16(uint8_t *buf, uint16_t value, uint8_t index) {
  buf[index]     = (uint8_t)((value >> 8) & 0xFF);
  buf[index + 1] = (uint8_t)(value & 0xFF);
}

// Payload format (16 bytes total):
// 0–1:  temp_bme * 100      -> int16
// 2–3:  hum_bme * 100       -> uint16
// 4–5:  pressure * 10       -> uint16
// 6–7:  gas_kOhm * 100      -> uint16
// 8–9:  co2 ppm             -> uint16
// 10–11: temp_scd * 100     -> int16
// 12–13: hum_scd * 100      -> uint16
// 14–15: lux                -> uint16
void encodePayload(uint8_t *buffer, const SensorData &d) {
  int16_t  t_bme   = (int16_t)(d.temp_bme * 100.0f);
  uint16_t h_bme   = (uint16_t)(d.hum_bme * 100.0f);
  uint16_t p       = (uint16_t)(d.pressure * 10.0f);
  uint16_t gas     = (uint16_t)(d.gas_kOhm * 100.0f);
  uint16_t co2ppm  = (uint16_t)(d.co2);
  int16_t  t_scd   = (int16_t)(d.temp_scd * 100.0f);
  uint16_t h_scd   = (uint16_t)(d.hum_scd * 100.0f);
  uint16_t lx      = (uint16_t)(d.lux);

  putInt16 (buffer, t_bme,  0);
  putUInt16(buffer, h_bme,  2);
  putUInt16(buffer, p,      4);
  putUInt16(buffer, gas,    6);
  putUInt16(buffer, co2ppm, 8);
  putInt16 (buffer, t_scd,  10);
  putUInt16(buffer, h_scd,  12);
  putUInt16(buffer, lx,     14);
}

// ------------ Sensor initialization -------------
bool initSensors() {
  bool ok = true;

  // BME680 - RAK1906
  if (!bme.begin(0x76)) {
    Serial.println("BME680 (RAK1906) not found at 0x76");
    ok = false;
  } else {
    bme.setTemperatureOversampling(BME680_OS_8X);
    bme.setHumidityOversampling(BME680_OS_2X);
    bme.setPressureOversampling(BME680_OS_4X);
    bme.setIIRFilterSize(BME680_FILTER_SIZE_3);
    bme.setGasHeater(320, 150); // 320°C for 150 ms
    Serial.println("BME680 (RAK1906) initialized");
  }

  // SCD30 - RAK12004
  if (!airSensor.begin()) {
    Serial.println("SCD30 (RAK12004) not found");
    ok = false;
  } else {
    // optional: airSensor.setMeasurementInterval(2); // seconds
    Serial.println("SCD30 (RAK12004) initialized");
  }

  // BH1750 - RAK12019
  if (!lightMeter.begin(BH1750::CONTINUOUS_HIGH_RES_MODE)) {
    Serial.println("BH1750 (RAK12019) not found");
    ok = false;
  } else {
    Serial.println("BH1750 (RAK12019) initialized");
  }

  return ok;
}

// ------------ Sensor reading -------------
bool readSensors(SensorData &d) {
  // BME680
  if (!bme.performReading()) {
    Serial.println("Failed to perform BME680 reading");
    return false;
  }
  d.temp_bme = bme.temperature;
  d.hum_bme  = bme.humidity;
  d.pressure = bme.pressure / 100.0f;        // Pa -> hPa
  d.gas_kOhm = bme.gas_resistance / 1000.0f; // Ω -> kΩ

  // SCD30 (CO2)
  if (airSensor.dataAvailable()) {
    d.co2      = airSensor.getCO2();          // ppm
    d.temp_scd = airSensor.getTemperature();  // °C
    d.hum_scd  = airSensor.getHumidity();     // %RH
  } else {
    Serial.println("SCD30 data not ready yet");
    // keep previous values if any; not fatal
  }

  // BH1750
  d.lux = lightMeter.readLightLevel();       // lux

  return true;
}

// ------------ Debug printing -------------
void printSensorData(const SensorData &d) {
  Serial.print("BME680 -> T: ");
  Serial.print(d.temp_bme); Serial.print(" °C, RH: ");
  Serial.print(d.hum_bme);  Serial.print(" %, P: ");
  Serial.print(d.pressure); Serial.print(" hPa, Gas: ");
  Serial.print(d.gas_kOhm); Serial.println(" kΩ");

  Serial.print("SCD30  -> CO2: ");
  Serial.print(d.co2);     Serial.print(" ppm, T: ");
  Serial.print(d.temp_scd);Serial.print(" °C, RH: ");
  Serial.print(d.hum_scd); Serial.println(" %");

  Serial.print("Light  -> ");
  Serial.print(d.lux);     Serial.println(" lux");
}

void printPayload(const uint8_t *payload, size_t len) {
  Serial.print("Payload [");
  Serial.print(len);
  Serial.print(" bytes]: ");
  for (size_t i = 0; i < len; i++) {
    if (payload[i] < 16) Serial.print("0");
    Serial.print(payload[i], HEX);
    Serial.print(" ");
  }
  Serial.println();
}

// ------------- Arduino setup/loop -------------
void setup() {
  Serial.begin(115200);
  while (!Serial) {
    delay(10);
  }

  Serial.println("Smart Meeting Room CO2 & Comfort Monitor");
  Serial.println("RAK4631 + RAK1906 + RAK12004 + RAK12019");

  Wire.begin();

  if (!initSensors()) {
    Serial.println("One or more sensors failed to initialize.");
  } else {
    Serial.println("All sensors initialized successfully.");
  }

  // Initialize LoRaWAN here using your existing WisBlock TTN guide:
  // https://www.hackster.io/user2702447/getting-started-with-wisblock-and-the-things-network-ttn-0a7b84
}

void loop() {
  if (readSensors(data)) {
    printSensorData(data);

    uint8_t payload[16];
    encodePayload(payload, data);
    printPayload(payload, sizeof(payload));

    // Integrate this payload with your LoRaWAN uplink logic from:
    // https://www.hackster.io/user2702447/getting-started-with-wisblock-and-the-things-network-ttn-0a7b84
    //
    // Example concept:
    //   g_lora_app_data.buffer = payload;
    //   g_lora_app_data.buffsize = sizeof(payload);
    //   lmh_send(&g_lora_app_data, LORAWAN_PORT);
  } else {
    Serial.println("Sensor reading failed.");
  }

  // Send data every 60 seconds (adjust as needed)
  delay(60000);
}

Step 5 – TTN Uplink Decoder (JavaScript)

In TTN Console → Application → Payload formatters → Uplink, add:

function decodeUInt16(bytes, index) {
  return (bytes[index] << 8) | bytes[index + 1];
}

function decodeInt16(bytes, index) {
  var value = (bytes[index] << 8) | bytes[index + 1];
  if (value & 0x8000) {
    value = value - 0x10000;
  }
  return value;
}

function decodeUplink(input) {
  var bytes = input.bytes;
  if (!bytes || bytes.length < 16) {
    return { errors: ["Invalid payload length"] };
  }

  var t_bme  = decodeInt16(bytes, 0)  / 100.0;
  var rh_bme = decodeUInt16(bytes, 2) / 100.0;
  var p      = decodeUInt16(bytes, 4) / 10.0;
  var gas    = decodeUInt16(bytes, 6) / 100.0;
  var co2    = decodeUInt16(bytes, 8) * 1.0;
  var t_scd  = decodeInt16(bytes, 10) / 100.0;
  var rh_scd = decodeUInt16(bytes, 12) / 100.0;
  var lux    = decodeUInt16(bytes, 14) * 1.0;

  return {
    data: {
      bme_temp_c: t_bme,
      bme_hum_pct: rh_bme,
      pressure_hpa: p,
      gas_kohm: gas,
      co2_ppm: co2,
      scd_temp_c: t_scd,
      scd_hum_pct: rh_scd,
      lux: lux
    }
  };
}

These fields will be visible in TTN and then passed to Ubidots through your webhook integration, configured like in:https://www.hackster.io/user2702447/set-up-ttn-webhooks-integrate-with-ubidots-a-guide-b715d9

Step 6 – Ubidots Integration & Dashboard

In TTN, create a Webhook → Ubidots for this application (same pattern as your webhook guide).

In Ubidots, create a Plugin for The Things Stack / TTN.

Ensure the plugin receives the JSON fields:

bme_temp_c, bme_hum_pct, pressure_hpa, gas_kohm,

co2_ppm, scd_temp_c, scd_hum_pct, lux

• Ensure the plugin receives the JSON fields:bme_temp_c, bme_hum_pct, pressure_hpa, gas_kohm,co2_ppm, scd_temp_c, scd_hum_pct, lux


In Ubidots Devices, you’ll see a device with these variables.

Build a Meeting Room dashboard:

Time series for co2_ppm, bme_temp_c, bme_hum_pct

Gauge for co2_ppm with colored thresholds

Lux graph to see usage patterns (lights on/off)

• Build a Meeting Room dashboard:Time series for co2_ppm, bme_temp_c, bme_hum_pct

Gauge for co2_ppm with colored thresholdsLux graph to see usage patterns (lights on/off)

Configure Events / Alerts:

CO₂ alert when co2_ppm > 1000 (needs ventilation)

Comfort alert when bme_temp_c or bme_hum_pct out of range

“Lights on but CO₂ high” combined condition for smart hints

• Configure Events / Alerts:CO₂ alert when co2_ppm > 1000 (needs ventilation)Comfort alert when bme_temp_c or bme_hum_pct out of range“Lights on but CO₂ high” combined condition for smart hints

Challenges & Troubleshooting

No readings from sensors

Check I²C slots exactly like in the original single-sensor projects:

RAK1906: https://www.hackster.io/user2702447/rak1906-air-quality-monitoring-a-focused-guide-on-environme-d2c0d0

RAK12004: https://www.hackster.io/user2702447/advanced-indoor-air-quality-monitoring-rak1906-and-rak12004-e05935

RAK12019: https://www.hackster.io/532551/smart-air-quality-and-light-monitoring-system-using-iot-3a3989

• No readings from sensorsCheck I²C slots exactly like in the original single-sensor projects:RAK1906: https://www.hackster.io/user2702447/rak1906-air-quality-monitoring-a-focused-guide-on-environme-d2c0d0RAK12004: https://www.hackster.io/user2702447/advanced-indoor-air-quality-monitoring-rak1906-and-rak12004-e05935RAK12019: https://www.hackster.io/532551/smart-air-quality-and-light-monitoring-system-using-iot-3a3989

Weird values in TTN / Ubidots

Confirm payload format in encodePayload() matches the TTN decoder exactly (order + scaling).

• Confirm payload format in encodePayload() matches the TTN decoder exactly (order + scaling).
• Weird values in TTN / UbidotsConfirm payload format in encodePayload() matches the TTN decoder exactly (order + scaling).

TTN receives but Ubidots doesn’t

Re-check TTN webhook + Ubidots plugin as in:https://www.hackster.io/user2702447/set-up-ttn-webhooks-integrate-with-ubidots-a-guide-b715d9

LoRaWAN join issues

Verify keys and region following:https://www.hackster.io/user2702447/getting-started-with-wisblock-and-the-things-network-ttn-0a7b84