Manhole Hazard Monitoring System

#include <Arduino.h>
#include <SPI.h>
#include <RadioLib.h>

// Enter the OTAA credentials issued for this individual node by your LoRaWAN server.
// Each value is hexadecimal text without spaces. Do not reuse device credentials.

// Forward declarations
void inspectGasLine(const String &line);
void readGasMonitor();
void updateInputs();
void sendStatus();

// Replace these zero placeholders with the hexadecimal OTAA values assigned to this node.
// RadioLib expects EUIs as 64-bit values and keys as 16 raw bytes.
const uint64_t JOIN_EUI = 0x0000000000000000ULL;
const uint64_t DEV_EUI  = 0x0000000000000000ULL;
const uint8_t NWK_KEY[16] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
const uint8_t APP_KEY[16] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};

constexpr int GAS_RX_PIN = 16;
constexpr int GAS_TX_PIN = 17;
constexpr int WATER_PIN = 26;
constexpr int COVER_PIN = 27;
constexpr int RODENT_PIN = 32;
constexpr int BUZZER_PIN = 25;
constexpr int LORA_SCK_PIN = 18;
constexpr int LORA_MISO_PIN = 19;
constexpr int LORA_MOSI_PIN = 23;
constexpr int LORA_NSS_PIN = 4;
constexpr int LORA_DIO1_PIN = 33;
constexpr int LORA_RESET_PIN = 13;
constexpr int LORA_BUSY_PIN = 14;

constexpr uint8_t LORAWAN_PORT = 10;
constexpr unsigned long REPORT_INTERVAL_MS = 300000UL;
constexpr unsigned long DEBOUNCE_MS = 60;

HardwareSerial gasSerial(2);
SX1262 radio = new Module(LORA_NSS_PIN, LORA_DIO1_PIN, LORA_RESET_PIN, LORA_BUSY_PIN);
LoRaWANNode node(&radio, &AS923);

bool waterAlarm = false;
bool coverAlarm = false;
bool gasAlarm = false;
bool lorawanJoined = false;
uint32_t rodentCount = 0;
int lastRodentRaw = HIGH;
unsigned long lastRodentEdgeMs = 0;
unsigned long lastReportMs = 0;
String gasLine;

void inspectGasLine(const String &line) {
  String upper = line;
  upper.toUpperCase();
  // The gas monitor itself must have its alarm thresholds configured by qualified staff.
  gasAlarm = upper.indexOf("ALARM") >= 0 || upper.indexOf("FAULT") >= 0;
}

void readGasMonitor() {
  while (gasSerial.available()) {
    char c = static_cast<char>(gasSerial.read());
    if (c == '\n' || c == '\r') {
      if (gasLine.length() > 0) {
        inspectGasLine(gasLine);
        gasLine = "";
      }
    } else if (gasLine.length() < 120) {
      gasLine += c;
    }
  }
}

void updateInputs() {
  // Normally-closed circuits: an open contact or cut cable becomes an alarm.
  waterAlarm = digitalRead(WATER_PIN) == HIGH;
  coverAlarm = digitalRead(COVER_PIN) == HIGH;

  int rodentRaw = digitalRead(RODENT_PIN);
  if (lastRodentRaw == HIGH && rodentRaw == LOW && millis() - lastRodentEdgeMs > DEBOUNCE_MS) {
    ++rodentCount;
    lastRodentEdgeMs = millis();
  }
  lastRodentRaw = rodentRaw;

  digitalWrite(BUZZER_PIN, (waterAlarm || coverAlarm || gasAlarm) ? HIGH : LOW);
}

void sendStatus() {
  // Compact LoRaWAN payload: flags, 16-bit rodent count, and joined-state marker.
  uint8_t payload[4];
  payload[0] = (waterAlarm ? 0x01 : 0x00) |
               (coverAlarm ? 0x02 : 0x00) |
               (gasAlarm ? 0x04 : 0x00);
  payload[1] = static_cast<uint8_t>((rodentCount >> 8) & 0xFF);
  payload[2] = static_cast<uint8_t>(rodentCount & 0xFF);
  payload[3] = 1;

  if (!lorawanJoined) {
    Serial.println("LoRaWAN not joined; status retained for next report.");
    return;
  }

  // sendReceive also listens during LoRaWAN receive windows for network commands.
  uint8_t downlink[32];
  size_t downlinkLength = 0;
  int state = node.sendReceive(payload, sizeof(payload), LORAWAN_PORT,
                               downlink, &downlinkLength);
  if (state >= RADIOLIB_ERR_NONE) {
    Serial.println("LoRaWAN status sent.");
  } else {
    Serial.printf("LoRaWAN uplink failed: %d\n", state);
  }
}

void setup() {
  Serial.begin(115200);
  gasSerial.begin(9600, SERIAL_8N1, GAS_RX_PIN, GAS_TX_PIN);
  pinMode(WATER_PIN, INPUT_PULLUP);
  pinMode(COVER_PIN, INPUT_PULLUP);
  pinMode(RODENT_PIN, INPUT_PULLUP);
  pinMode(BUZZER_PIN, OUTPUT);
  digitalWrite(BUZZER_PIN, LOW);

  SPI.begin(LORA_SCK_PIN, LORA_MISO_PIN, LORA_MOSI_PIN, LORA_NSS_PIN);
  int state = radio.begin();
  if (state != RADIOLIB_ERR_NONE) {
    Serial.printf("SX1262 startup failed: %d\n", state);
    return;
  }

  node.beginOTAA(JOIN_EUI, DEV_EUI, NWK_KEY, APP_KEY);
  state = node.activateOTAA();
  lorawanJoined = (state == RADIOLIB_LORAWAN_NEW_SESSION || state == RADIOLIB_LORAWAN_SESSION_RESTORED);
  if (lorawanJoined) {
    Serial.println("Joined Singapore AS923 LoRaWAN network.");
  } else {
    Serial.printf("LoRaWAN join failed: %d\n", state);
  }
  sendStatus();
}

void loop() {
  readGasMonitor();
  updateInputs();

  if (millis() - lastReportMs >= REPORT_INTERVAL_MS) {
    lastReportMs = millis();
    sendStatus();
  }
}