Vehicle GPS Tracker

#include <Arduino.h>

// Replace every value between angle brackets before deploying.
// This sketch uses Traccar's OsmAnd HTTP protocol by default.
const char APN[] = "<YOUR_SIM_APN>";
const char APN_USER[] = "";       // Fill only if your carrier supplied one.
const char APN_PASSWORD[] = "";   // Fill only if your carrier supplied one.
const char TRACCAR_HOST[] = "<YOUR_TRACCAR_HOST>";
const uint16_t TRACCAR_PORT = 5055; // Replace with your OsmAnd HTTP port.
const char DEVICE_ID[] = "<YOUR_TRACCAR_DEVICE_ID>";

const int MODEM_RX_PIN = 16;      // ESP32 receives from SIM7080G TX
const int MODEM_TX_PIN = 17;      // ESP32 transmits to SIM7080G RX
const int MODEM_PWRKEY_PIN = 27;  // Active-low SIM7080G power key
const int MODEM_RESET_PIN = 26;   // Active-low SIM7080G reset
const unsigned long REPORT_INTERVAL_MS = 30000UL;

HardwareSerial modem(2);
unsigned long lastReportMs = 0;

String readModem(unsigned long timeoutMs) {
  String response;
  const unsigned long deadline = millis() + timeoutMs;
  while ((long)(deadline - millis()) > 0) {
    while (modem.available()) {
      response += static_cast<char>(modem.read());
    }
    delay(5);
  }
  if (response.length()) {
    Serial.print(response);
  }
  return response;
}

String command(const String &text, unsigned long timeoutMs = 1500) {
  while (modem.available()) modem.read();
  Serial.print(">> ");
  Serial.println(text);
  modem.println(text);
  return readModem(timeoutMs);
}

bool commandOK(const String &text, unsigned long timeoutMs = 1500) {
  return command(text, timeoutMs).indexOf("OK") >= 0;
}

void powerOnModem() {
  pinMode(MODEM_PWRKEY_PIN, OUTPUT);
  pinMode(MODEM_RESET_PIN, OUTPUT);
  digitalWrite(MODEM_PWRKEY_PIN, HIGH);
  digitalWrite(MODEM_RESET_PIN, HIGH);
  delay(200);
  // A low pulse longer than one second requests SIM7080G power-on.
  digitalWrite(MODEM_PWRKEY_PIN, LOW);
  delay(1200);
  digitalWrite(MODEM_PWRKEY_PIN, HIGH);
  delay(5000);
}

bool initialiseModem() {
  for (int attempt = 0; attempt < 5; ++attempt) {
    if (commandOK("AT", 1000)) break;
    delay(1000);
    if (attempt == 4) return false;
  }
  commandOK("ATE0");
  commandOK("AT+CMEE=2");
  commandOK("AT+CGNSPWR=1", 2000);
  // Configure PDP context 0 for the SIM carrier. Quote marks are required by AT syntax.
  if (!commandOK(String("AT+CGDCONT=0,\"IP\",\"") + APN + "\"", 3000)) return false;
  commandOK("AT+CNACT=0,0", 3000); // Drop any stale mobile-data session.
  if (!commandOK("AT+CNACT=0,1", 10000)) return false;
  String state = command("AT+CNACT?", 2000);
  return state.indexOf(",1,") >= 0 || state.indexOf("+CNACT: 0,1") >= 0;
}

bool getGnssFix(String &latitude, String &longitude) {
  String answer = command("AT+CGNSINF", 2500);
  int prefix = answer.indexOf("+CGNSINF:");
  if (prefix < 0) return false;
  String fields = answer.substring(prefix + 9);
  int lineEnd = fields.indexOf('\r');
  if (lineEnd >= 0) fields.remove(lineEnd);

  String values[8];
  int start = 0;
  for (int i = 0; i < 8; ++i) {
    int comma = fields.indexOf(',', start);
    if (comma < 0) {
      values[i] = fields.substring(start);
      break;
    }
    values[i] = fields.substring(start, comma);
    start = comma + 1;
  }
  // Fields are: run status, fix status, UTC, latitude, longitude, ...
  if (values[1] != "1" || values[3].length() == 0 || values[4].length() == 0) return false;
  latitude = values[3];
  longitude = values[4];
  return true;
}

bool sendToTraccar(const String &latitude, const String &longitude) {
  String hostPort = String(TRACCAR_HOST) + ":" + String(TRACCAR_PORT);
  String path = String("/?id=") + DEVICE_ID + "&lat=" + latitude + "&lon=" + longitude;

  commandOK("AT+SHDISC", 3000);
  if (!commandOK(String("AT+SHCONF=\"URL\",\"") + hostPort + "\"", 3000)) return false;
  if (!commandOK("AT+SHCONF=\"BODYLEN\",350", 2000)) return false;
  if (!commandOK("AT+SHCONF=\"HEADERLEN\",350", 2000)) return false;
  if (!commandOK("AT+SHCONN", 10000)) return false;
  String response = command(String("AT+SHREQ=\"") + path + "\",1", 15000);
  commandOK("AT+SHDISC", 3000);
  // Traccar normally returns HTTP 200 for an accepted OsmAnd update.
  return response.indexOf("200") >= 0;
}

void setup() {
  Serial.begin(115200);
  modem.begin(115200, SERIAL_8N1, MODEM_RX_PIN, MODEM_TX_PIN);
  delay(300);
  Serial.println("Vehicle tracker starting");
  powerOnModem();
  if (!initialiseModem()) {
    Serial.println("Modem setup failed. Check the SIM, APN, antennas, and 3.8 V modem supply.");
  }
}

void loop() {
  if (millis() - lastReportMs < REPORT_INTERVAL_MS) return;
  lastReportMs = millis();

  String latitude;
  String longitude;
  if (!getGnssFix(latitude, longitude)) {
    Serial.println("Waiting for a satellite position fix.");
    return;
  }

  Serial.print("Position: ");
  Serial.print(latitude);
  Serial.print(", ");
  Serial.println(longitude);

  if (sendToTraccar(latitude, longitude)) {
    Serial.println("Traccar accepted the location update.");
  } else {
    Serial.println("Location was not accepted. Check the placeholders and network registration.");
  }
}