SSL HTTPS Post on SIM7600

Using Arduino Programming Questions
1

Hi all, I'm trying to build a GPS tracking system. I'm using a SIM7672S-based ESP for internet connectivity, and I'm able to push data through ThingSpeak. However, when I tried to use Firebase, it didn't work. The same code works with Wi-Fi, so I figured it's most probably an SSL issue. I wanted to bring this to the forum to get a solution.

#define TINY_GSM_MODEM_SIM7600
#include <TinyGsmClient.h>
#include <FirebaseESP32.h>
#include <TinyGPS++.h>
#include <HardwareSerial.h>
#include <WiFi.h>

#define WIFI_SSID "xxxxx"
#define WIFI_PASSWORD "xxxxx"
// Create a TinyGPS++ object
TinyGPSPlus gps;

// Define the serial connections
HardwareSerial gpsSerial(1);

// Define the serial interface for the SIM7600 module
#define MODEM_PWRKEY 4
#define MODEM_POWER_ON 23
#define MODEM_RST 5

// Firebase settings
#define FIREBASE_HOST "xxxxx" // Replace with your Firebase database URL
#define FIREBASE_AUTH "xxxxx" // Replace with your Firebase API key

// Use hardware serial port 2
HardwareSerial SerialAT(2);
TinyGsm modem(SerialAT);

// Firebase Data object
FirebaseData firebaseData;
FirebaseAuth auth;
FirebaseConfig config;

// Define the posting interval (in milliseconds)
const unsigned long postingInterval = 20000; // Replace with your desired posting interval

void setup() {
  // Initialize serial for debugging
  Serial.begin(115200);
  delay(10);
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);

  // Initialize GPS serial communication
  gpsSerial.begin(115200, SERIAL_8N1, 16, 17);

  // Start the hardware serial communication with the modem
  SerialAT.begin(115200, SERIAL_8N1, 27, 26); // RX2 -> GPIO16, TX2 -> GPIO17
  delay(3000);

  Serial.println("GPS Data Parsing with TinyGPS++ and IST Conversion");

  // Initialize the modem
  Serial.println("Initializing modem...");
  modem.restart();

  // Print modem info
  String modemInfo = modem.getModemInfo();
  Serial.println("Modem Info: " + modemInfo);

  // Check signal quality
  int16_t signalQuality = modem.getSignalQuality();
  Serial.println("Signal quality: " + String(signalQuality));

  // Connect to network
  Serial.print("Connecting to network...");
  if (!modem.gprsConnect("airtelgprs.com", "", "")) { // Replace "your_apn" with the actual APN
    Serial.println(" fail");
  } else {
    Serial.println(" success");
  }

  // Check network connection
  Serial.print("Testing connection...");
  if (modem.isNetworkConnected()) {
    Serial.println(" connected");
  } else {
    Serial.println(" not connected");
  }

  // Initialize Firebase
  config.host = FIREBASE_HOST;
  config.signer.tokens.legacy_token = FIREBASE_AUTH;
  Firebase.begin(&config, &auth);
  Firebase.reconnectWiFi(true);
}

void loop() {
  while (gpsSerial.available() > 0) {
    gps.encode(gpsSerial.read());

    if (gps.location.isUpdated()) {
      Serial.print("Latitude: ");
      Serial.println(gps.location.lat(), 6);
      Serial.print("Longitude: ");
      Serial.println(gps.location.lng(), 6);
    }

    if (gps.date.isUpdated() && gps.time.isUpdated()) {
      // Get the UTC time and date from the GPS
      int year = gps.date.year();
      int month = gps.date.month();
      int day = gps.date.day();
      int hour = gps.time.hour();
      int minute = gps.time.minute();
      int second = gps.time.second();

      // Convert to IST (UTC + 5:30)
      minute += 30;
      if (minute >= 60) {
        minute -= 60;
        hour += 1;
      }
      hour += 5;
      if (hour >= 24) {
        hour -= 24;
        day += 1;
        // Adjust month and year for end of month/year
        if ((month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10) && day > 31) {
          day = 1;
          month += 1;
        } else if (month == 12 && day > 31) {
          day = 1;
          month = 1;
          year += 1;
        } else if ((month == 4 || month == 6 || month == 9 || month == 11) && day > 30) {
          day = 1;
          month += 1;
        } else if (month == 2) {
          // Leap year check
          bool isLeap = (year % 4 == 0 && (year % 100 != 0 || year % 400 == 0));
          if ((isLeap && day > 29) || (!isLeap && day > 28)) {
            day = 1;
            month += 1;
          }
        }
      }

      Serial.print("Date (IST): ");
      Serial.print(day);
      Serial.print("/");
      Serial.print(month);
      Serial.print("/");
      Serial.println(year);

      Serial.print("Time (IST): ");
      if (hour < 10) Serial.print("0");
      Serial.print(hour);
      Serial.print(":");
      if (minute < 10) Serial.print("0");
      Serial.print(minute);
      Serial.print(":");
      if (second < 10) Serial.print("0");
      Serial.println(second);

      // Prepare data for Firebase
      String date = String(day) + "/" + String(month) + "/" + String(year);
      String time = String(hour) + ":" + String(minute) + ":" + String(second);

      float latitude = gps.location.lat();
      float longitude = gps.location.lng();
      float altitude = gps.altitude.meters();
      float speed = gps.speed.kmph();
      int satellites = gps.satellites.value();

      // Push data to Firebase
      pushToFirebase(latitude, longitude, altitude, speed, satellites, date, time);

      // Wait for the posting interval
      delay(postingInterval);
    }
  }
}

void pushToFirebase(float latitude, float longitude, float altitude, float speed, int satellites, String date, String time) {
  String path = "/gps_data";
  FirebaseJson json;

  json.set("latitude", latitude);
  json.set("longitude", longitude);
  json.set("altitude", altitude);
  json.set("speed", speed);
  json.set("satellites", satellites);
  json.set("date", date);
  json.set("time", time);

  if (Firebase.pushJSON(firebaseData, path, json)) {
    Serial.println("Data sent to Firebase successfully.");
  } else {
    Serial.print("Failed to send data to Firebase: ");
    Serial.println(firebaseData.errorReason());
  }
}