DustSensorDSM.ino

/*
 * The MySensors Arduino library handles the wireless radio link and protocol
 * between your home built sensors/actuators and HA controller of choice.
 * The sensors forms a self healing radio network with optional repeaters. Each
 * repeater and gateway builds a routing tables in EEPROM which keeps track of the
 * network topology allowing messages to be routed to nodes.
 *
 * Created by Henrik Ekblad <[email protected]>
 * Copyright (C) 2013-2022 Sensnology AB
 * Full contributor list: https://github.com/mysensors/MySensors/graphs/contributors
 *
 * Documentation: http://www.mysensors.org
 * Support Forum: http://forum.mysensors.org
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 *
 *******************************
 *
 * DESCRIPTION
 *
 * Dust Sensor for SamYoung DSM501
 *   connect the sensor as follows :
 *    Pin 2 of dust sensor PM1      -> Digital 3 (PMW)
 *    Pin 3 of dust sensor          -> +5V
 *    Pin 4 of dust sensor PM2.5    -> Digital 6 (PWM)
 *    Pin 5 of dust sensor          -> Ground
 * Datasheet: http://www.samyoungsnc.com/products/3-1%20Specification%20DSM501.pdf
* Contributor: epierre
**/
 
// Enable debug prints
#define MY_DEBUG
 
// Enable and select radio type attached
#define MY_RADIO_RF24
//#define MY_RADIO_NRF5_ESB
//#define MY_RADIO_RFM69
//#define MY_RADIO_RFM95
 
#include <MySensors.h>
 
#define CHILD_ID_DUST_PM10            0
#define CHILD_ID_DUST_PM25            1
#define DUST_SENSOR_DIGITAL_PIN_PM10  6
#define DUST_SENSOR_DIGITAL_PIN_PM25  3
 
uint32_t SLEEP_TIME = 30*1000; // Sleep time between reads (in milliseconds)
//VARIABLES
int val = 0;           // variable to store the value coming from the sensor
float valDUSTPM25 =0.0;
float lastDUSTPM25 =0.0;
float valDUSTPM10 =0.0;
float lastDUSTPM10 =0.0;
uint32_t duration;
uint32_t starttime;
uint32_t endtime;
uint32_t sampletime_ms = 30000;
uint32_t lowpulseoccupancy = 0;
float ratio = 0;
long concentrationPM25 = 0;
long concentrationPM10 = 0;
 
MyMessage dustMsgPM10(CHILD_ID_DUST_PM10, V_LEVEL);
MyMessage msgPM10(CHILD_ID_DUST_PM10, V_UNIT_PREFIX);
MyMessage dustMsgPM25(CHILD_ID_DUST_PM25, V_LEVEL);
MyMessage msgPM25(CHILD_ID_DUST_PM25, V_UNIT_PREFIX);
 
void setup()
{
    pinMode(DUST_SENSOR_DIGITAL_PIN_PM10,INPUT);
    pinMode(DUST_SENSOR_DIGITAL_PIN_PM25,INPUT);
}
 
void presentation()
{
    // Send the sketch version information to the gateway and Controller
    sendSketchInfo("Dust Sensor DSM501", "1.4");
 
    // Register all sensors to gateway (they will be created as child devices)
    present(CHILD_ID_DUST_PM10, S_DUST);
    send(msgPM10.set("ppm"));
    present(CHILD_ID_DUST_PM25, S_DUST);
    send(msgPM25.set("ppm"));
}
 
void loop()
{
 
    //get PM 2.5 density of particles over 2.5 µm.
    concentrationPM25=(long)getPM(DUST_SENSOR_DIGITAL_PIN_PM25);
    Serial.print("PM25: ");
    Serial.println(concentrationPM25);
    Serial.print("\n");
 
    if ((concentrationPM25 != lastDUSTPM25)&&(concentrationPM25>0)) {
        send(dustMsgPM25.set((int32_t)ceil(concentrationPM25)));
        lastDUSTPM25 = ceil(concentrationPM25);
    }
 
    //get PM 1.0 - density of particles over 1 µm.
    concentrationPM10=getPM(DUST_SENSOR_DIGITAL_PIN_PM10);
    Serial.print("PM10: ");
    Serial.println(concentrationPM10);
    Serial.print("\n");
    //ppmv=mg/m3 * (0.08205*Tmp)/Molecular_mass
    //0.08205   = Universal gas constant in atm·m3/(kmol·K)
    int temp=20; //external temperature, if you can replace this with a DHT11 or better
    long ppmv=(concentrationPM10*0.0283168/100/1000) *  (0.08205*temp)/0.01;
 
    if ((ceil(concentrationPM10) != lastDUSTPM10)&&((long)concentrationPM10>0)) {
        send(dustMsgPM10.set((int32_t)ppmv));
        lastDUSTPM10 = ceil(concentrationPM10);
    }
 
    //sleep to save on radio
    sleep(SLEEP_TIME);
 
}
 
 
long getPM(int DUST_SENSOR_DIGITAL_PIN)
{
 
    starttime = millis();
 
    while (1) {
 
        duration = pulseIn(DUST_SENSOR_DIGITAL_PIN, LOW);
        lowpulseoccupancy += duration;
        endtime = millis();
 
        if ((endtime-starttime) > sampletime_ms) {
            ratio = (lowpulseoccupancy-endtime+starttime)/(sampletime_ms*10.0);  // Integer percentage 0=>100
            long concentration = 1.1*pow(ratio,3)-3.8*pow(ratio,2)+520*ratio+0.62; // using spec sheet curve
            //Serial.print("lowpulseoccupancy:");
            //Serial.print(lowpulseoccupancy);
            //Serial.print("\n");
            //Serial.print("ratio:");
            //Serial.print(ratio);
            //Serial.print("\n");
            //Serial.print("DSM501A:");
            //Serial.println(concentration);
            //Serial.print("\n");
 
            lowpulseoccupancy = 0;
            return(concentration);
        }
    }
}