Remote environment sensor using BME280 and Dust Particulate sensor, with Wemos D1 Mini and Cayenne cloud platform

#define CAYENNE_DEBUG
#define CAYENNE_PRINT Serial
#include <CayenneMQTTESP8266.h>
#include <Wire.h>
#include <SPI.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BME280.h>
#include<string.h>
#define PM1PIN 14 //DSM501A input D6 on ESP8266
#define PM25PIN 12 //DSM501A input D5 on ESP8266
byte buff[2];
unsigned long durationPM1;
unsigned long durationPM25;
unsigned long starttime;
unsigned long endtime;
unsigned long sampletime_ms = 30000;
unsigned long lowpulseoccupancyPM1 = 0;
unsigned long lowpulseoccupancyPM25 = 0;
Adafruit_BME280 bme; // I2C
// WiFi network info.
char ssid[] = "MO CONNECT KA?";
char wifiPassword[] = "AMBOTwalakokabalo_2022";
// Cayenne authentication info. This should be obtained from the Cayenne Dashboard.
char username[] = "e3849d00-ab91-11ed-b0e7-e768b61d6137";
char password[] = "5b7630330806de309ce7c343c63bc997d80044bb";
char clientID[] = "13b95b60-ad35-11ed-b0e7-e768b61d6137";
int i=0;
void setup() {
  Serial.begin(9600);
    unsigned status;
   status = bme.begin(0x76);
    Serial.println();
  pinMode(PM1PIN,INPUT);
  pinMode(PM25PIN,INPUT);
  starttime = millis();
  Cayenne.begin(username, password, clientID, ssid, wifiPassword);
}
float calculateConcentration(long lowpulseInMicroSeconds, long durationinSeconds)
{
 
  float ratio = (lowpulseInMicroSeconds/1000000.0)/30.0*100.0; //Calculate the ratio
  float concentration = 0.001915 * pow(ratio,2) + 0.09522 * ratio - 0.04884;//Calculate the mg/m3
  Serial.print("lowpulseoccupancy:");
  Serial.print(lowpulseInMicroSeconds);
  Serial.print("    ratio:");
  Serial.print(ratio);
  Serial.print("    Concentration:");
  Serial.println(concentration);
  return concentration;
}
void loop() {
  Cayenne.loop();
   printValues();
   
  durationPM1 = pulseIn(PM1PIN, LOW);
  durationPM25 = pulseIn(PM25PIN, LOW);
 
  lowpulseoccupancyPM1 += durationPM1;
  lowpulseoccupancyPM25 += durationPM25;
 
  endtime = millis();
  if ((endtime-starttime) > sampletime_ms) //Only after 30s has passed we calcualte the ratio
  {
    float conPM1 = calculateConcentration(lowpulseoccupancyPM1,30);
    float conPM25 = calculateConcentration(lowpulseoccupancyPM25,30);
    Serial.print("PM1 ");
    Serial.print(conPM1);
    Serial.print("  PM25 ");
    Serial.println(conPM25);
    lowpulseoccupancyPM1 = 0;
    lowpulseoccupancyPM25 = 0;
    starttime = millis();
 
  Cayenne.virtualWrite(4, conPM1);
  Cayenne.virtualWrite(5, conPM25);
}
}
void printValues() {
    Serial.print("Temperature = ");
    Serial.print(bme.readTemperature());
    Serial.println(" °C");
    Serial.print("Pressure = ");
    Serial.print(bme.readPressure() / 100.0F);
    Serial.println(" hPa");
    Serial.print("Humidity = ");
    Serial.print(bme.readHumidity());
    Serial.println(" %");
    Serial.println();
}
CAYENNE_OUT_DEFAULT()
{
 Cayenne.celsiusWrite(1, bme.readTemperature());
  Cayenne.virtualWrite(2, bme.readPressure()/100, "bp", "pa");
  Cayenne.virtualWrite(3, bme.readHumidity(), "rel_hum", "p");
}

Code Breakdown: 

Libraries:

Tells the compiler to use the BME280 sensor library. Can be download in Arduino's Library manager.

• #define CAYENNE_PRINT Serial
• Enables Cayenne Serial Print

• char username[]
• Device's Cayenne username (provided in the Cayenne link code)
• char password[]
• Device's Cayenne password (provided in the Cayenne link code)
• char clientID[]
• Device's Cayenne client ID (provided in the Cayenne link code)

• Cayenne.begin(username, password, clientID)
• Starts cayenne connection and displays status
• Cayenne.loop()
• Calls the CAYENNE_OUT(VIRTUAL_CHANNEL) class
• Cayenne.virtualWrite()

             Uploads the sensor output value to the Cayenn's dashboard

Dust particulate sensor DSM501A and BME280

•  unsigned long - The time allotted to stabilize the sensor before requesting output value
•  float conPM1 and float conPM25 - calculating the concentration
• bme.read() - gets the output from the BME280 sensor
• printValues() - gets updated sensor output to display on serial monitor

 

Note: Before on checking the output, check first the table below which shows the Air quality index (AQI) values, PM2.5 and PM10 conc. air pollution levels, color codes, and health concerns. This will assist you in interpreting the Dust Particulate Sensor DSM501a's output. (Research gate)

 

Cayenne output:

Video Demonstration: 

 

Conclusion:

We have demonstrated in this mini project the use of WEMOS D1 Mini as main controller to read data from BME280 sensor and DSM501A dust particle sensor. Using Wi-fi to transmit data to Cayene cloud platform, we were able to display data in the web browser in real-time. Sensor modules like these can have a significant help in environment monitoring.

 

References: 

• https://www.researchgate.net/figure/Air-quality-index-AQI-values-PM25-and-PM10-conc-color-codes-air-pollutant-level-of_tbl1_343404673
• https://www.instructables.com/Dust-Sensor-With-DSM501a-and-ESP8266/
• https://www.connectedlittleboxes.com/proj02temperaturedisplay.html
• http://www.esp8266learning.com/esp8266-and-bme280-temperature-sensor-example.php