#include <LiquidCrystal.h>

// LCD connections (RS, EN, D4, D5, D6, D7)
LiquidCrystal lcd(12, 11, 10, 9, 8, 7);

// Analog pins for AD8307
const byte analogPinF = A0; // Forward power
const byte analogPinR = A1; // Reflected power

// AD8307 calibration parameters
const float Vreference = 5000.0; // mV
const float slopeF = 0.02618;    // Slope for forward power
const float interceptF = 45.2;   // Intercept for forward power
const float slopeR = 0.02618;    // Slope for reflected power (adjust if different)
const float interceptR = 45.2;   // Intercept for reflected power (adjust if different)

// Power measurement variables
float pow_fwd = 0;           // Forward power in Watts
float pow_ref = 0;           // Reflected power in Watts
float peak_power = 0;        // Peak power in Watts
float swr = 1.0;             // Standing Wave Ratio
unsigned long last_peak_time = 0;
const unsigned long peak_hold_time = 2000; // 2 seconds peak hold

// Bar graph variables
const byte bar_length = 16;  // LCD width
float bar_level = 0;         // Current bar level (0-1)
float bar_decay = 0.95;      // Decay factor per loop (adjust for slower/faster decay)
const float bar_threshold = 0.01; // Minimum bar level to display

void setup() {
  // Initialize LCD
  lcd.begin(16, 2);
  
  // Display initial information
  lcd.setCursor(0, 0);
  lcd.print("Po:");
  lcd.setCursor(11, 0);
  lcd.print("SW:");
  
  // Configure ADC for better performance
  analogReference(DEFAULT);
  ADCSRA = (ADCSRA & 0xF8) | 0x04; // Set ADC clock divider to 16 (1MHz/16 = 62.5kHz)
}

void loop() {
  // Read forward and reflected power
  readPower();
  
  // Calculate SWR
  calculateSWR();
  
  // Update peak power
  updatePeak();
  
  // Update bar graph
  updateBarGraph();
  
  // Update display
  updateDisplay();
  
}

void readPower() {
  // Read forward power
  int adcValueF = analogRead(analogPinF);
  float voltageF = (adcValueF / 1023.0) * Vreference; 
  float powerdBmF = (slopeF * voltageF) - interceptF; 
  pow_fwd = pow(10, (powerdBmF - 30) / 10);
  
  // Read reflected power
  int adcValueR = analogRead(analogPinR);
  float voltageR = (adcValueR / 1023.0) * Vreference; 
  float powerdBmR = (slopeR * voltageR) - interceptR;
  pow_ref = pow(10, (powerdBmR - 30) / 10);
}

void calculateSWR() {
  // Calculate SWR with protection against division by zero and negative roots
  if (pow_fwd > 0 && pow_ref >= 0) {
    float gamma = sqrt(pow_ref / pow_fwd);
    if (gamma < 1.0) {
      swr = (1.0 + gamma) / (1.0 - gamma);
    } else {
      swr = 99.99; // Max SWR we'll display
    }
  } else {
    swr = 1.0;
  }
}

void updatePeak() {
  // Update peak power if current power is higher
  if (pow_fwd > peak_power) {
    peak_power = pow_fwd;
    last_peak_time = millis();
  }
  // Reset peak after hold time if no new peak detected
  else if (millis() - last_peak_time > peak_hold_time) {
    peak_power = pow_fwd;
  }
}

void updateBarGraph() {
  // Update bar level - fast attack, slow decay
  float target_level = pow_fwd / 100.0; // Assuming 100W max for bar graph (adjust as needed)
  
  if (target_level > bar_level) {
    bar_level = target_level; // Fast attack
  } else {
    bar_level *= bar_decay; // Slow decay
  }
  
  // Clear bar if below threshold
  if (bar_level < bar_threshold) {
    bar_level = 0;
  }
}

void updateDisplay() {
  // Update peak power display
  lcd.setCursor(0, 0);
  lcd.print("Po:");
  if (peak_power < 10) {
    lcd.print(int(peak_power));
    lcd.print("W ");
  } else if (peak_power < 100) {
    lcd.print(int(peak_power));
    lcd.print("W");
  } else {
    lcd.print(int(peak_power));
    lcd.print("W");
  }
  
  // Update SWR display
  lcd.setCursor(10, 0);
  lcd.print("SW:");
  if (swr < 10.0) {
    lcd.print(swr, 2);
  } else {
    lcd.print(swr, 1);
  }
  
  // Update bar graph on second line
  lcd.setCursor(0, 1);
  if (bar_level == 0) {
    lcd.print("                "); // Clear line if no power
  } else {
    int bars = round(bar_level * bar_length);
    bars = constrain(bars, 0, bar_length);
    for (int i = 0; i < bars; i++) {
      lcd.write(0xFF); // Custom character for solid block
    }
    for (int i = bars; i < bar_length; i++) {
      lcd.write(' '); // Fill rest with spaces
    }
  }
}