ESP32 Air Quality Monitor with ThingsBoard

#include <WiFi.h>
#include <HTTPClient.h>

// Serial is used for debug log printing
// Serial2 is used for ZMOD4510 sensor interface

// Set up WiFi and serial ports
void setup()
{
  Serial.begin (115200);

  // Set up UART for ZMOD4510 module, 9600-8-N-1
  Serial2.begin (9600, SERIAL_8N1, 5, 4); // Rx and Tx
  Serial2.setTimeout(1000);

  // Delay needed before WiFi is set up
  delay (5000);
  WiFi.begin ("WIFI_SSID", "WIFI_PASSWORD");

  while (WiFi.status() != WL_CONNECTED)
  {
    delay (1000);
    Serial.println ("Connecting to WiFi network...");
  }
  Serial.println ("Connected!");
}

void loop()
{
  char zmod_response[16];
  String ID, AQI, NO2, O3, AQIjson;

  // Loop until module responds to power up command
  while (1)
  {
    // Issue PU command and read response
    Serial2.print ("PU\n");
    memset (zmod_response, 0, sizeof(zmod_response));
    Serial2.readBytesUntil('\n', zmod_response, 16);
    
    if (zmod_response[0] != 'S')
    {
      // Could not get desired response to PU command
      Serial.println ("Trying to initialize ZMOD4510 module...");
      delay (1000);
      continue;
    }
    else
    {
      // All good!
      Serial.println ("ZMOD4510 is powered up!");
      break;
    }
  }

  // Issue ID command and read response
  Serial2.print ("ID\n");
  memset (zmod_response, 0, sizeof(zmod_response));
  Serial2.readBytesUntil('\n', zmod_response, 16);
  ID = zmod_response;
  Serial.println ("ZMOD4510 module ID is 0x" + ID);

  // Get data from module
  while (1)
  {
    // Issue AQ command and read AQI value
    Serial2.print ("AQ\n");
    memset (zmod_response, 0, sizeof(zmod_response));
    Serial2.readBytesUntil('\n', zmod_response, 16);
    Serial.printf ("Debug AQI $: %s\n", zmod_response);
    AQI = zmod_response;

    // Issue NO command and read NO2 value
    Serial2.print ("NO\n");
    memset (zmod_response, 0, sizeof(zmod_response));
    Serial2.readBytesUntil('\n', zmod_response, 16);
    Serial.printf ("Debug NO $: %s\n", zmod_response);
    NO2 = zmod_response;

    // Issue O3 command and read O3 value
    Serial2.print ("O3\n");
    memset (zmod_response, 0, sizeof(zmod_response));
    Serial2.readBytesUntil('\n', zmod_response, 16);
    Serial.printf ("Debug O3 $: %s\n", zmod_response);
    O3 = zmod_response;

    // {"id": "AABBCCDD", "aqi": 10.0, "no2": 20.0, "o3": 30.0}
    AQIjson = "{\"id\": " + ID + ", \"aqi\": " + AQI + ", \"no2\": " + NO2 + ", \"o3\": " + O3 + "}";
    Serial.println ("JSON: \n" + AQIjson);

    // Make a POST request with the data if WiFi is connected
    if ((WiFi.status() == WL_CONNECTED))
    {
      //Check the current connection status
      HTTPClient http;
      
      http.begin("https://demo.thingsboard.io/api/v1/THINGSBOARD_ACCESS_TOKEN/telemetry");
      http.addHeader("Content-Type", "application/json");
      int httpResponseCode = http.POST(AQIjson);   //Send the actual POST request
  
      if(httpResponseCode>0)
      {
        String response = http.getString();                       //Get the response to the request
        Serial.println(httpResponseCode);   //Print return code
        Serial.println(response);           //Print request answer
      }
      else
      {
        Serial.print("Error on sending POST request: ");
        Serial.println(httpResponseCode);
      }
      
      http.end();  //Free resources
    }
    else
    {
      Serial.println ("Something wrong with WiFi?");
    }

    delay (10*60*1000);  // 10 * 60 seconds between updates
  }
}