IoT GPS Tracker with Movement Alert and LoRaWAN

C++
// Project: GPS Tracker for Assets/People with Movement Alert
// Board: RAK4631 (Nordic NRF52840)
// Base: RAK1903
// Sensors: RAK12500 ZOE-M8Q GNSS GPS Module, RAK12033 IM-42652 6-axis Accelerometer
// LoRaWAN Platform: The Things Stack
 
#include <Wire.h>
#include <TinyGPS++.h> // For GPS
#include <SoftwareSerial.h> // If GPS uses SoftwareSerial, otherwise use Serial1/HardwareSerial
#include <LoRaWan-RAK4631.h> // LoRaWAN library for RAK4631
#include <SPI.h>
 
// Library for accelerometer (example, may vary based on exact IM-42652 model)
// #include <SparkFun_ICM-20948_Arduino_Library.h> // If using ICM-20948
 
// LoRaWAN Configuration (OTAA) - REPLACE WITH YOUR THE THINGS STACK CREDENTIALS!
uint8_t nodeDeviceEUI[8] = {0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX};
uint8_t nodeAppEUI[8] = {0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX};
uint8_t nodeAppKey[16] = {0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX, 0xXX};
 
// LoRaWAN Region Configuration
LoRaMacRegion_t loraWanRegion = LORAMAC_REGION_EU868;
 
// Pins for GPS (RAK12500 connects via UART, use Serial1 on RAK4631)
#define GPS_SERIAL Serial1 // RAK12500 connects to UART1 of RAK4631
#define GPS_BAUDRATE 9600
 
// Instances
TinyGPSPlus gps;
// ICM_20948_I2C accel; // If using ICM-20948
 
// Variables to store readings
float latitude, longitude, altitude;
float accel_x, accel_y, accel_z;
bool movement_detected = false;
 
void setup() {
  Serial.begin(115200);
  delay(100);
  Serial.println("Starting IoT GPS Tracker...");
 
  Wire.begin(); // For I2C accelerometer
 
  // Initialize GPS
  GPS_SERIAL.begin(GPS_BAUDRATE);
 
  // Initialize accelerometer (placeholder)
  // if (accel.begin()!= ICM_20948_Stat_Ok) {
  //   Serial.println("Could not find accelerometer, check wiring.");
  //   while (1);
  // }
 
  // Initialize LoRaWAN
  if (api.lorawan.setRegion(loraWanRegion)) {
    Serial.printf("LoRaWAN region configured to %d\n", loraWanRegion);
  } else {
    Serial.println("Failed to configure LoRaWAN region.");
    while (1);
  }
 
  if (api.lorawan.setAppKey(nodeAppKey) &&
     api.lorawan.setAppEUI(nodeAppEUI) &&
     api.lorawan.setDevEUI(nodeDeviceEUI)) {
    Serial.println("LoRaWAN credentials configured.");
  } else {
    Serial.println("Failed to configure LoRaWAN credentials.");
    while (1);
  }
 
  Serial.println("Attempting to join LoRaWAN network (OTAA)...");
  if (api.lorawan.join()) {
    Serial.println("Joined LoRaWAN network!");
  } else {
    Serial.println("Failed to join LoRaWAN network. Retrying...");
    while(1);
  }
  delay(2000);
}
 
void loop() {
  readSensors();
 
  // Send data if there's a new GPS fix or if movement is detected
  if (gps.location.isUpdated() || movement_detected) {
    sendLoRaWANData();
  }
 
  Serial.println("Entering low power mode...");
  api.system.sleep.all(30000); // Sleep for 30 seconds
}
 
void readSensors() {
  // Process GPS data
  while (GPS_SERIAL.available() > 0) {
    gps.encode(GPS_SERIAL.read());
  }
 
  if (gps.location.isValid()) {
    latitude = gps.location.lat();
    longitude = gps.location.lng();
    altitude = gps.altitude.meters();
    Serial.printf("GPS: Lat %.6f, Lng %.6f, Alt %.2f m\n", latitude, longitude, altitude);
  } else {
    Serial.println("GPS: No fix or invalid data.");
  }
 
  // Read accelerometer (placeholder)
  // accel.readSensor();
  // accel_x = accel.getAccelX_G();
  // accel_y = accel.getAccelY_G();
  // accel_z = accel.getAccelZ_G();
  // Serial.printf("Accel X: %.2f, Y: %.2f, Z: %.2f G\n", accel_x, accel_y, accel_z);
 
  // Simple movement detection logic
  // movement_detected = (abs(accel_x) > 0.1 || abs(accel_y) > 0.1 || abs(accel_z) > 0.1); // Movement threshold
  movement_detected = false; // Placeholder if actual accelerometer is not used
  if (movement_detected) {
    Serial.println("Movement detected!");
  }
}
 
void sendLoRaWANData() {
  // Payload format:
  // Byte 0-3: Latitude (float to int32 x1000000)
  // Byte 4-7: Longitude (float to int32 x1000000)
  // Byte 8-9: Altitude (int16)
  // Byte 10: Movement status (0=No, 1=Yes)
 
  uint8_t payload[11]; // Changed from 12 to 11 to match new byte calculation
  int32_t lat_int = (int32_t)(latitude * 1000000);
  int32_t lng_int = (int32_t)(longitude * 1000000);
  int16_t alt_int = (int16_t)altitude;
 
  payload[0] = (lat_int >> 24) & 0xFF;
  payload[1] = (lat_int >> 16) & 0xFF;
  payload[2] = (lat_int >> 8) & 0xFF;
  payload[3] = lat_int & 0xFF;
 
  payload[4] = (lng_int >> 24) & 0xFF;
  payload[5] = (lng_int >> 16) & 0xFF;
  payload[6] = (lng_int >> 8) & 0xFF;
  payload[7] = lng_int & 0xFF;
 
  payload[8] = (alt_int >> 8) & 0xFF;
  payload[9] = alt_int & 0xFF;
 
  payload[10] = movement_detected? 1 : 0;
 
  Serial.print("Sending LoRaWAN packet: ");
  for (int i = 0; i < sizeof(payload); i++) {
    Serial.printf("%02X ", payload[i]);
  }
  Serial.println();
 
  if (api.lorawan.send(sizeof(payload), payload, 1, true)) { // Port 1, confirmed
    Serial.println("LoRaWAN packet sent successfully.");
  } else {
    Serial.println("Failed to send LoRaWAN packet.");
  }
}
 
// Example Payload Formatter (Decoder) for The Things Stack (Custom Javascript)
/*
function decodeUplink(input) {
  var data = {};
  var bytes = input.bytes;
 
  // Decode latitude (4 bytes, int32, x1000000)
  data.latitude = (bytes[0] << 24 | bytes[1] << 16 | bytes[2] << 8 | bytes[3]) / 1000000.0;
 
  // Decode longitude (4 bytes, int32, x1000000)
  data.longitude = (bytes[4] << 24 | bytes[5] << 16 | bytes[6] << 8 | bytes[7]) / 1000000.0;
 
  // Decode altitude (2 bytes, int16)
  data.altitude = (bytes[8] << 8 | bytes[9]);
 
  // Decode movement status (1 byte, boolean)
  data.movement_detected = (bytes[10] === 1);
 
  return {
    data: data,
    warnings: [],
    errors: []
  };
}
*/