Project Documentation

Arduino-Based Air Quality Monitoring System with Bluetooth Connectivity

Circuit Documentation

Summary

This circuit is designed to monitor air quality using a PM2.5 Air Quality Sensor (PMS5003) and an MQ131 ozone sensor. The data is processed by an Arduino UNO and can be transmitted via an HC-05 Bluetooth module. The circuit is powered by a 9V battery and includes a rocker switch for power control.

Component List

PM2.5 Air Quality Sensor and Breadboard Adapter Kit - PMS5003
- Description: Measures particulate matter (PM) concentrations in the air.
- Pins: VCC, GND, SET, RX, TX, RST
MQ131
- Description: Ozone gas sensor.
- Pins: GND, AOUT, DOUT, VCC
Rocker Switch
- Description: Used to control the power supply to the circuit.
- Pins: 1, 2
Arduino UNO
- Description: Microcontroller used to process sensor data and control other components.
- Pins: UNUSED, IOREF, Reset, 3.3V, 5V, GND, Vin, A0, A1, A2, A3, A4, A5, SCL, SDA, AREF, D13, D12, D11, D10, D9, D8, D7, D6, D5, D4, D3, D2, D1, D0
HC-05 Bluetooth Module
- Description: Bluetooth module for wireless communication.
- Pins: Key, VCC, GND, TXD, RXD, State
Resistor (2000 Ohms)
- Description: Limits current in the circuit.
- Pins: pin1, pin2
Resistor (1000 Ohms)
- Description: Limits current in the circuit.
- Pins: pin1, pin2
9V Battery
- Description: Power supply for the circuit.
- Pins: -, +

Wiring Details

PM2.5 Air Quality Sensor and Breadboard Adapter Kit - PMS5003

VCC connected to 5V on Arduino UNO
GND connected to GND on Arduino UNO
RX connected to D3 on Arduino UNO
TX connected to D2 on Arduino UNO

MQ131

VCC connected to 5V on Arduino UNO
GND connected to GND on Arduino UNO
DOUT connected to D2 on Arduino UNO
AOUT connected to A1 on Arduino UNO

Rocker Switch

Pin 1 connected to D7 on Arduino UNO
Pin 2 connected to GND on Arduino UNO

Arduino UNO

5V connected to VCC on PM2.5 Air Quality Sensor, MQ131, and HC-05 Bluetooth Module
GND connected to GND on PM2.5 Air Quality Sensor, MQ131, and HC-05 Bluetooth Module
D3 connected to RX on PM2.5 Air Quality Sensor
D2 connected to TX on PM2.5 Air Quality Sensor and DOUT on MQ131
A1 connected to AOUT on MQ131
D7 connected to Pin 1 on Rocker Switch
Vin connected to + on 9V Battery
GND connected to - on 9V Battery

HC-05 Bluetooth Module

VCC connected to 5V on Arduino UNO
GND connected to GND on Arduino UNO
TXD connected to D1 on Arduino UNO
RXD connected to pin1 on 1000 Ohms Resistor

Resistor (2000 Ohms)

Pin 1 connected to RXD on HC-05 Bluetooth Module
Pin 2 connected to - on 9V Battery

Resistor (1000 Ohms)

Pin 1 connected to D0 on Arduino UNO
Pin 2 connected to pin1 on 2000 Ohms Resistor

9V Battery

+ connected to Vin on Arduino UNO
- connected to GND on Arduino UNO and pin2 on 2000 Ohms Resistor

Documented Code

Arduino UNO Code

#include <SoftwareSerial.h>
SoftwareSerial pmsSerial(2, 3);

void setup() {
  // our debugging output
  Serial.begin(115200);

  // sensor baud rate is 9600
  pmsSerial.begin(9600);
}

struct pms5003data {
  uint16_t framelen;
  uint16_t pm10_standard, pm25_standard, pm100_standard;
  uint16_t pm10_env, pm25_env, pm100_env;
  uint16_t particles_03um, particles_05um, particles_10um, particles_25um, particles_50um, particles_100um;
  uint16_t unused;
  uint16_t checksum;
};

struct pms5003data data;

void loop() {
  if (readPMSdata(&pmsSerial)) {
    // reading data was successful!
    Serial.println();
    Serial.println("---------------------------------------");
    Serial.println("Concentration Units (standard)");
    Serial.print("PM 1.0: "); Serial.print(data.pm10_standard);
    Serial.print("\t\tPM 2.5: "); Serial.print(data.pm25_standard);
    Serial.print("\t\tPM 10: "); Serial.println(data.pm100_standard);
    Serial.println("---------------------------------------");
    Serial.println("Concentration Units (environmental)");
    Serial.print("PM 1.0: "); Serial.print(data.pm10_env);
    Serial.print("\t\tPM 2.5: "); Serial.print(data.pm25_env);
    Serial.print("\t\tPM 10: "); Serial.println(data.pm100_env);
    Serial.println("---------------------------------------");
    Serial.print("Particles > 0.3um / 0.1L air:"); Serial.println(data.particles_03um);
    Serial.print("Particles > 0.5um / 0.1L air:"); Serial.println(data.particles_05um);
    Serial.print("Particles > 1.0um / 0.1L air:"); Serial.println(data.particles_10um);
    Serial.print("Particles > 2.5um / 0.1L air:"); Serial.println(data.particles_25um);
    Serial.print("Particles > 5.0um / 0.1L air:"); Serial.println(data.particles_50um);
    Serial.print("Particles > 10.0 um / 0.1L air:"); Serial.println(data.particles_100um);
    Serial.println("---------------------------------------");
  }
}

boolean readPMSdata(Stream *s) {
  if (! s->available()) {
    return false;
  }

  // Read a byte at a time until we get to the special '0x42' start-byte
  if (s->peek() != 0x42) {
    s->read();
    return false;
  }

  // Now read all 32 bytes
  if (s->available() < 32) {
    return false;
  }

  uint8_t buffer[32];    
  uint16_t sum = 0;
  s->readBytes(buffer, 32);

  // get checksum ready
  for (uint8_t i=0; i<30; i++) {
    sum += buffer[i];
  }

  /* debugging
  for (uint8_t i=2; i<32; i++) {
    Serial.print("0x"); Serial.print(buffer[i], HEX); Serial.print(", ");
  }
  Serial.println();
  */

  // The data comes in endian'd, this solves it so it works on all platforms
  uint16_t buffer_u16[15];
  for (uint8_t i=0; i<15; i++) {
    buffer_u16[i] = buffer[2 + i*2 + 1];
    buffer_u16[i] += (buffer[2 + i*2] << 8);
  }

  // put it into a nice struct :)
  memcpy((void *)&data, (void *)buffer_u16, 30);

  if (sum != data.checksum) {
    Serial.println("Checksum failure");
    return false;
  }
  // success!
  return true;
}

This documentation provides a comprehensive overview of the circuit, including a summary, detailed component list, wiring details, and the code used in the Arduino UNO.