arduino/examples/DIY_PRO/DIY_PRO.ino

/*
This is the code for the AirGradient DIY Air Quality Sensor with an ESP8266 Microcontroller.

It is a high quality sensor showing PM2.5, CO2, Temperature and Humidity on a small display and can send data over Wifi.

For build instructions please visit https://www.airgradient.com/diy/

Instructions on using the TVOC sensor (SGP30) instead of the Temperature / Humidity sensor (SHT3x).

https://www.airgradient.com/resources/tvoc-on-airgradient-diy-sensor/

The codes needs the following libraries installed:
“WifiManager by tzapu, tablatronix” tested with version 2.0.11-beta
“U8g2” by oliver tested with version 2.32.15
“SGP30” by Rob Tilaart tested with Version 0.1.5

Configuration:
Please set in the code below which sensor you are using and if you want to connect it to WiFi.

If you have any questions please visit our forum at https://forum.airgradient.com/

If you are a school or university contact us for a free trial on the AirGradient platform.
https://www.airgradient.com/schools/

MIT License

*/


#include <AirGradient.h>
#include <WiFiManager.h>
#include <ESP8266WiFi.h>
#include <ESP8266HTTPClient.h>
#include <WiFiClient.h>

#include "SGP30.h"
#include <U8g2lib.h>

AirGradient ag = AirGradient();
SGP30 SGP;
U8G2_SH1106_128X64_NONAME_F_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);

unsigned long currentMillis = 0;

const int oledInterval = 5000;
unsigned long previousOled = 0;

const int sendToServerInterval = 10000;
unsigned long previoussendToServer = 0;

const int tvocInterval = 1000;
unsigned long previousTVOC = 0;
int TVOC = 0;

const int co2Interval = 5000;
unsigned long previousCo2 = 0;
int Co2 = 0;

const int pm25Interval = 5000;
unsigned long previousPm25 = 0;
int pm25 = 0;

const int tempHumInterval = 2500;
unsigned long previousTempHum = 0;
float temp = 0;
int hum = 0;

String APIROOT = "http://hw.airgradient.com/";

// set to true to switch PM2.5 from ug/m3 to US AQI
boolean inUSaqi = true;

// set to true to switch from Celcius to Fahrenheit
boolean inF = true;

// set to true if you want to connect to wifi. The display will show values only when the sensor has wifi connection
boolean connectWIFI=true;


void setup()
{
  Serial.begin(115200);

  u8g2.begin();
  updateOLED();

    if (connectWIFI) {
    connectToWifi();
  }

  updateOLED2("Warming up the", "sensors.", "");

  Serial.println(SGP.begin());
  SGP.GenericReset();

  ag.CO2_Init();
  ag.PMS_Init();
  ag.TMP_RH_Init(0x44);
}


void loop()
{
  currentMillis = millis();
  updateTVOC();
  updateOLED();
  updateCo2();
  updatePm25();
  updateTempHum();
  sendToServer();
}

void updateTVOC()
{
    if (currentMillis - previousTVOC >= tvocInterval) {
      previousTVOC += tvocInterval;
      SGP.measure(true);
      TVOC = SGP.getTVOC();
      Serial.println(String(TVOC));
    }
}

void updateCo2()
{
    if (currentMillis - previousCo2 >= co2Interval) {
      previousCo2 += co2Interval;
      Co2 = ag.getCO2_Raw();
      Serial.println(String(Co2));
    }
}

void updatePm25()
{
    if (currentMillis - previousPm25 >= pm25Interval) {
      previousPm25 += pm25Interval;
      pm25 = ag.getPM2_Raw();
      Serial.println(String(pm25));
    }
}

void updateTempHum()
{
    if (currentMillis - previousTempHum >= tempHumInterval) {
      previousTempHum += tempHumInterval;
      TMP_RH result = ag.periodicFetchData();
      temp = result.t;
      hum = result.rh;
      Serial.println(String(temp));
    }
}

void updateOLED() {
   if (currentMillis - previousOled >= oledInterval) {
     previousOled += oledInterval;
     String ln1;
     String ln2;
      if (inUSaqi) {
        ln1 = "CO2:" + String(Co2) + " AQI:" + String(PM_TO_AQI_US(pm25));
        } else {
        ln1 = "CO2:" + String(Co2) + " PM:" + String(pm25);
       }

      if (inF) {
        ln2 = "F:" + String((temp* 9 / 5) + 32) + " H:" + String(hum)+"%";
        } else {
        ln2 = "C:" + String(temp) + " H:" + String(hum)+"%";
       }

     String ln3 = "TVOC:" + String(TVOC) ;
     updateOLED2(ln1, ln2, ln3);
   }
}

void updateOLED2(String ln1, String ln2, String ln3) {
      char buf[9];
        u8g2.firstPage();
          u8g2.firstPage();
          do {
          u8g2.setFont(u8g2_font_t0_16_tf);
          u8g2.drawStr(1, 10, String(ln1).c_str());
          u8g2.drawStr(1, 30, String(ln2).c_str());
          u8g2.drawStr(1, 50, String(ln3).c_str());
            } while ( u8g2.nextPage() );
}

void sendToServer() {
   if (currentMillis - previoussendToServer >= sendToServerInterval) {
     previoussendToServer += sendToServerInterval;
      String payload = "{\"wifi\":" + String(WiFi.RSSI())
      + ", \"rco2\":" + String(Co2)
      + ", \"pm02\":" + String(pm25)
      + ", \"tvoc\":" + String(TVOC)
      + ", \"atmp\":" + String(temp)
      + ", \"rhum\":" + String(hum)
      + "}";

      if(WiFi.status()== WL_CONNECTED){
        Serial.println(payload);
        String POSTURL = APIROOT + "sensors/airgradient:" + String(ESP.getChipId(), HEX) + "/measures";
        Serial.println(POSTURL);
        WiFiClient client;
        HTTPClient http;
        http.begin(client, POSTURL);
        http.addHeader("content-type", "application/json");
        int httpCode = http.POST(payload);
        String response = http.getString();
        Serial.println(httpCode);
        Serial.println(response);
        http.end();
      }
      else {
        Serial.println("WiFi Disconnected");
      }
   }
}

// Wifi Manager
 void connectToWifi() {
   WiFiManager wifiManager;
   //WiFi.disconnect(); //to delete previous saved hotspot
   String HOTSPOT = "AG-" + String(ESP.getChipId(), HEX);
   updateOLED2("To setup connect", "to Wifi Hotspot", HOTSPOT);
   wifiManager.setTimeout(120);
   if (!wifiManager.autoConnect((const char * ) HOTSPOT.c_str())) {
     Serial.println("failed to connect and hit timeout");
     delay(3000);
     ESP.restart();
     delay(5000);
   }
}

// Calculate PM2.5 US AQI
int PM_TO_AQI_US(int pm02) {
  if (pm02 <= 12.0) return ((50 - 0) / (12.0 - .0) * (pm02 - .0) + 0);
  else if (pm02 <= 35.4) return ((100 - 50) / (35.4 - 12.0) * (pm02 - 12.0) + 50);
  else if (pm02 <= 55.4) return ((150 - 100) / (55.4 - 35.4) * (pm02 - 35.4) + 100);
  else if (pm02 <= 150.4) return ((200 - 150) / (150.4 - 55.4) * (pm02 - 55.4) + 150);
  else if (pm02 <= 250.4) return ((300 - 200) / (250.4 - 150.4) * (pm02 - 150.4) + 200);
  else if (pm02 <= 350.4) return ((400 - 300) / (350.4 - 250.4) * (pm02 - 250.4) + 300);
  else if (pm02 <= 500.4) return ((500 - 400) / (500.4 - 350.4) * (pm02 - 350.4) + 400);
  else return 500;
};