// Arduino SENDER - Reads Sensor Data and Sends Hex Packets
// Upload this to the Arduino that will act as the sensor device

#include <Wire.h>

// Hex codes for data types
#define TEMP_CODE     0x01
#define HUMIDITY_CODE 0x02
#define CO2_CODE      0x03
#define RTC_HOUR_CODE 0x04
#define RTC_MIN_CODE  0x05
#define STATUS_CODE   0x0A
#define PACKET_START  0xAA
#define PACKET_END    0xFF

// Device Configuration
#define DEVICE_ID     0x05  // This device's unique ID
#define MASTER_ID     0x01  // Master device ID

// Simulated sensor pins
#define TEMP_SENSOR_PIN 32
#define HUM_SENSOR_PIN 33
#define CO2_SENSOR_PIN 34

// Global variables
float temperature = 0.0;
float humidity = 0.0;
uint16_t co2 = 0;
uint8_t rtc_hour = 14;
uint8_t rtc_minute = 30;
uint8_t system_status = 0b00001111; // All sensors OK
uint32_t packet_counter = 0;

// Packet storage
uint8_t packet[32];
uint8_t packetLength = 0;

void setup() {
  Serial.begin(9600);
  
  // Initialize analog pins
  pinMode(TEMP_SENSOR_PIN, INPUT);
  pinMode(HUM_SENSOR_PIN, INPUT);
  pinMode(CO2_SENSOR_PIN, INPUT);
  
  // Initialize random seed
  randomSeed(analogRead(0));
  
  Serial.println("========================================");
  Serial.println("    ARDUINO SENSOR DEVICE (SENDER)");
  Serial.println("         Device ID: 0x05");
  Serial.println("========================================");
  Serial.println("Generating sensor data and hex packets...");
  Serial.println("Connect this to RECEIVER for testing");
  Serial.println("========================================");
  
  delay(2000);
}

void loop() {
  // Read sensor data
  readSensorData();
  
  // Create hex packet
  createHexPacket();
  
  // Display what we're sending (for debugging)
  displayPacketInfo();
  
  // Send the hex packet over serial
  sendHexPacket();
  
  // Update time for next reading
  updateTime();
  
  // Wait before next transmission (simulate polling interval)
  delay(10000);
}

void readSensorData() {
  // Read analog sensors and convert to realistic values
  int tempReading = analogRead(TEMP_SENSOR_PIN);
  int humReading = analogRead(HUM_SENSOR_PIN);
  int co2Reading = analogRead(CO2_SENSOR_PIN);
  
  // Convert analog readings to realistic sensor values
  // Temperature: -10.0 to 50.0°C
  temperature = map(tempReading, 0, 1023, -100, 500) / 10.0;
  
  // Humidity: 0.0 to 100.0%
  humidity = map(humReading, 0, 1023, 0, 1000) / 10.0;
  
  // CO2: 300 to 2000 ppm
  co2 = map(co2Reading, 0, 1023, 300, 2000);
  
  // Simulate occasional sensor errors (5% chance)
  if (random(0, 100) < 5) {
    system_status = 0b00001011; // Temperature sensor error
  } else {
    system_status = 0b00001111; // All sensors OK
  }
  
  packet_counter++;
}

void createHexPacket() {
  uint8_t index = 0;
  
  // Build packet with device addressing
  packet[index++] = PACKET_START;           // 0xAA - Start marker
  packet[index++] = DEVICE_ID;              // 0x05 - Source device ID
  packet[index++] = MASTER_ID;              // 0x01 - Destination (master)
  uint8_t length_pos = index++;             // Reserve space for length
  packet[index++] = 5;                      // Data count (5 measurements)
  
  // Temperature (multiply by 10 for decimal precision)
  packet[index++] = TEMP_CODE;
  uint16_t temp_encoded = (uint16_t)(temperature * 10);
  packet[index++] = (temp_encoded >> 8) & 0xFF;  // High byte
  packet[index++] = temp_encoded & 0xFF;         // Low byte
  
  // Humidity (multiply by 10 for decimal precision)
  packet[index++] = HUMIDITY_CODE;
  uint16_t hum_encoded = (uint16_t)(humidity * 10);
  packet[index++] = (hum_encoded >> 8) & 0xFF;
  packet[index++] = hum_encoded & 0xFF;
  
  // CO2 (direct value)
  packet[index++] = CO2_CODE;
  packet[index++] = (co2 >> 8) & 0xFF;
  packet[index++] = co2 & 0xFF;
  
  // RTC Hour
  packet[index++] = RTC_HOUR_CODE;
  packet[index++] = 0x00;
  packet[index++] = rtc_hour;
  
  // RTC Minute
  packet[index++] = RTC_MIN_CODE;
  packet[index++] = 0x00;
  packet[index++] = rtc_minute;
  
  // Set packet length (total bytes - start - length byte itself)
  packet[length_pos] = index - 3;
  
  // Calculate XOR checksum
  uint8_t checksum = 0;
  for (uint8_t i = 3; i < index; i++) {
    checksum ^= packet[i];
  }
  packet[index++] = checksum;
  packet[index++] = PACKET_END;             // 0xFF - End marker
  
  packetLength = index;
}

void displayPacketInfo() {
  Serial.print("PKT #");
  Serial.print(packet_counter);
  Serial.print(" | Device 0x");
  Serial.print(DEVICE_ID, HEX);
  Serial.print(" -> Master 0x");
  Serial.print(MASTER_ID, HEX);
  Serial.println();
  
  Serial.print("Data: T=");
  Serial.print(temperature, 1);
  Serial.print("C, H=");
  Serial.print(humidity, 1);
  Serial.print("%, CO2=");
  Serial.print(co2);
  Serial.print("ppm, Time=");
  if (rtc_hour < 10) Serial.print("0");
  Serial.print(rtc_hour);
  Serial.print(":");
  if (rtc_minute < 10) Serial.print("0");
  Serial.print(rtc_minute);
  Serial.print(", Status=0b");
  Serial.println(system_status, BIN);
  
  Serial.print("Hex Packet (");
  Serial.print(packetLength);
  Serial.print(" bytes): ");
  for (uint8_t i = 0; i < packetLength; i++) {
    if (packet[i] < 0x10) Serial.print("0");
    Serial.print(packet[i], HEX);
    Serial.print(" ");
  }
  Serial.println();
  Serial.println("----------------------------------------");
}

void sendHexPacket() {
  // Send binary data over serial
  Serial.write(packet, packetLength);
  Serial.flush(); // Ensure all data is sent
}

void updateTime() {
  rtc_minute++;
  if (rtc_minute >= 60) {
    rtc_minute = 0;
    rtc_hour++;
    if (rtc_hour >= 24) rtc_hour = 0;
  }
}