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

1. 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

2. MQ131

   • Description: Ozone gas sensor.
   • Pins: GND, AOUT, DOUT, VCC

3. Rocker Switch

   • Description: Used to control the power supply to the circuit.
   • Pins: 1, 2

4. 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

5. HC-05 Bluetooth Module

   • Description: Bluetooth module for wireless communication.
   • Pins: Key, VCC, GND, TXD, RXD, State

6. Resistor (2000 Ohms)

   • Description: Limits current in the circuit.
   • Pins: pin1, pin2

7. Resistor (1000 Ohms)

   • Description: Limits current in the circuit.
   • Pins: pin1, pin2

8. 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.