ESP32 Code

#include <WiFi.h>
#include <WebServer.h>

//--------Pin definitions for Sensors-------
#define SENSOR1 0
#define SENSOR2 1
#define SENSOR3 2
#define SENSOR4 3
#define SENSOR5 4
//------------------------------------------

//--------Pin definitions for the TB6612FNG Motor Driver----
#define AIN1 5
#define AIN2 6
#define BIN1 7
#define BIN2 8
#define PWMA 9
#define PWMB 10
//------------------------------------------------------------

//--------WiFi Configuration--------
const char* ssid = "Pranav's Line Follower";
const char* password = "DogBalls69";
WebServer server(80);
//---------------------------------

//--------Enter Line Details here---------
bool isBlackLine = 1;             //keep 1 in case of black line. In case of white line change this to 0
unsigned int lineThickness = 15;  //Enter line thickness in mm. Works best for thickness between 10 & 35
const unsigned int numSensors = 5;  // Using 5 sensors as requested
//-----------------------------------------

int P, D, I, previousError, PIDvalue;
double error;
int lsp, rsp;
int lfSpeed = 150;
int currentSpeed = 30;
int sensorWeight[5] = { 4, 2, 0, -2, -4 };
int activeSensors;
float Kp = 0.08;
float Kd = 0.15;
float Ki = 0;

int onLine = 1;
int minValues[5], maxValues[5], threshold[5];
int sensorValue[5], sensorArray[5];

bool isCalibrating = false;
bool isRunning = false;

String webPage = "";
String debugLog = ""; // Log to store debug messages

void setup() {
  Serial.begin(115200);

  // Initialize motor driver pins
  pinMode(AIN1, OUTPUT);
  pinMode(AIN2, OUTPUT);
  pinMode(BIN1, OUTPUT);
  pinMode(BIN2, OUTPUT);
  pinMode(PWMA, OUTPUT);
  pinMode(PWMB, OUTPUT);

  // Initialize sensor pins
  pinMode(SENSOR1, INPUT);
  pinMode(SENSOR2, INPUT);
  pinMode(SENSOR3, INPUT);
  pinMode(SENSOR4, INPUT);
  pinMode(SENSOR5, INPUT);

  // Set up proper PWM initialization
  /* ledcSetup(0, 5000, 8); // Channel 0, 5kHz, 8-bit resolution
  ledcSetup(1, 5000, 8); // Channel 1, 5kHz, 8-bit resolution
  ledcAttachPin(PWMA, 0); // Attach PWMA to channel 0
  ledcAttachPin(PWMB, 1); // Attach PWMB to channel 1 */

  if (!ledcAttach(PWMA, 5000, 8)) {
    Serial.println("LEDC attach failed!");
  }
  // Similarly for PWMB:
  if (!ledcAttach(PWMB, 5000, 8)) {
    Serial.println("LEDC attach failed!");
  }

  // Set up WiFi Access Point
  WiFi.softAP(ssid, password);
  IPAddress myIP = WiFi.softAPIP();
  Serial.print("AP IP address: ");
  Serial.println(myIP);
  logMessage("AP IP address: " + myIP.toString());

  // Set up Web Server routes
  server.on("/", handleRoot);
  server.on("/calibrate", handleCalibrate);
  server.on("/start", handleStart);
  server.on("/stop", handleStop);
  server.on("/sensors", handleSensors);
  server.on("/logs", handleLogs);
  server.on("/clearlogs", handleClearLogs);
  server.begin();
  Serial.println("HTTP server started");
  logMessage("HTTP server started");

  lineThickness = constrain(lineThickness, 10, 35);
}

void loop() {
  server.handleClient();

  if (isCalibrating) {
    calibrate();
    isCalibrating = false;
  }

  if (isRunning) {
    readLine();
    if (currentSpeed < lfSpeed) currentSpeed++;

    if (onLine == 1) {  // PID LINE FOLLOW
      linefollow();
    } else {
      if (error > 0) {
        motor1run(-50);
        motor2run(lfSpeed);
      } else {
        motor1run(lfSpeed);
        motor2run(-50);
      }
    }
  } else {
    // Stop motors when not running
    motor1run(0);
    motor2run(0);
  }
}

void handleRoot() {
  buildWebPage();
  server.send(200, "text/html", webPage);
}

void handleCalibrate() {
  isCalibrating = true;
  isRunning = false;
  logMessage("Starting calibration...");
  server.sendHeader("Location", "/");
  server.send(303);
}

void handleStart() {
  isRunning = true;
  logMessage("Robot started");
  server.sendHeader("Location", "/");
  server.send(303);
}

void handleStop() {
  isRunning = false;
  logMessage("Robot stopped");
  server.sendHeader("Location", "/");
  server.send(303);
}

void handleSensors() {
  String sensorJSON = "{";
  for (int i = 0; i < numSensors; i++) {
    int rawValue = analogRead(i);
    sensorJSON += "\"sensor" + String(i+1) + "\":{";
    sensorJSON += "\"raw\":" + String(rawValue) + ",";
    if (isRunning) {
      sensorJSON += "\"processed\":" + String(sensorValue[i]) + ",";
      sensorJSON += "\"binary\":" + String(sensorArray[i]);
    } else {
      sensorJSON += "\"processed\":0,";
      sensorJSON += "\"binary\":0";
    }
    sensorJSON += "}";
    if (i < numSensors-1) sensorJSON += ",";
  }
  sensorJSON += "}";

  server.send(200, "application/json", sensorJSON);
}

void handleLogs() {
  server.send(200, "text/plain", debugLog);
}

void handleClearLogs() {
  debugLog = "";
  logMessage("Logs cleared");
  server.sendHeader("Location", "/");
  server.send(303);
}

// Function to add messages to both Serial and web debug log
void logMessage(String message) {
  String timestamp = String(millis() / 1000.0, 2);
  String logEntry = "[" + timestamp + "s] " + message + "\n";

  Serial.print(logEntry);

  // Keep log size manageable (limit to last ~5000 chars)
  if (debugLog.length() > 5000) {
    int cutPoint = debugLog.indexOf('\n', debugLog.length() - 4000);
    if (cutPoint > 0) {
      debugLog = debugLog.substring(cutPoint + 1);
    }
  }

  debugLog += logEntry;
}

void buildWebPage() {
  webPage = "<!DOCTYPE html>";
  webPage += "<html lang='en'>";
  webPage += "<head>";
  webPage += "<meta charset='UTF-8'>";
  webPage += "<meta name='viewport' content='width=device-width, initial-scale=1.0'>";
  webPage += "<title>Line Follower Robot</title>";
  webPage += "<style>";
  webPage += "body { font-family: Arial, sans-serif; margin: 0; padding: 20px; max-width: 800px; margin: 0 auto; }";
  webPage += "h1 { color: #333; }";
  webPage += ".button { display: inline-block; background-color: #4CAF50; color: white; padding: 10px 20px; ";
  webPage += "text-align: center; text-decoration: none; font-size: 16px; margin: 4px 2px; cursor: pointer; border-radius: 4px; }";
  webPage += ".button.red { background-color: #f44336; }";
  webPage += ".button.blue { background-color: #2196F3; }";
  webPage += ".button.gray { background-color: #9e9e9e; }";
  webPage += ".sensors { margin-top: 20px; }";
  webPage += ".sensor-bar { height: 30px; margin: 5px 0; background-color: #ddd; position: relative; }";
  webPage += ".sensor-value { height: 100%; width: 0%; background-color: #4CAF50; position: absolute; left: 0; transition: width 0.3s ease; }";
  webPage += ".sensor-binary { width: 30px; height: 30px; display: inline-block; border-radius: 50%; margin-right: 10px; }";
  webPage += ".sensor-label { font-weight: bold; }";
  webPage += ".debug-log { margin-top: 20px; background-color: #f5f5f5; padding: 10px; border-radius: 4px; height: 200px; overflow-y: auto; font-family: monospace; white-space: pre-wrap; }";
  webPage += ".tabs { display: flex; border-bottom: 1px solid #ccc; margin-top: 20px; }";
  webPage += ".tab { padding: 10px 20px; cursor: pointer; background-color: #f1f1f1; border: 1px solid #ccc; border-bottom: none; margin-right: 5px; border-radius: 4px 4px 0 0; }";
  webPage += ".tab.active { background-color: white; border-bottom: 1px solid white; margin-bottom: -1px; }";
  webPage += ".tab-content { display: none; padding: 20px; border: 1px solid #ccc; border-top: none; }";
  webPage += ".tab-content.active { display: block; }";
  webPage += "</style>";
  webPage += "</head>";
  webPage += "<body>";
  webPage += "<h1>Line Follower Robot Control</h1>";
  webPage += "<div class='controls'>";
  webPage += "<a href='/calibrate' class='button blue'>Calibrate</a> ";

  if (isRunning) {
    webPage += "<a href='/stop' class='button red'>Stop</a>";
  } else {
    webPage += "<a href='/start' class='button'>Start</a>";
  }

  webPage += "</div>";

  webPage += "<div class='tabs'>";
  webPage += "<div class='tab active' onclick='openTab(\"sensors-tab\")'>Sensors</div>";
  webPage += "<div class='tab' onclick='openTab(\"status-tab\")'>Status</div>";
  webPage += "<div class='tab' onclick='openTab(\"debug-tab\")'>Debug Log</div>";
  webPage += "</div>";

  webPage += "<div id='sensors-tab' class='tab-content active'>";
  webPage += "<h2>Sensor Values</h2>";
  webPage += "<div class='sensors'>";

  for (int i = 0; i < numSensors; i++) {
    webPage += "<div class='sensor'>";
    webPage += "<div class='sensor-label'>Sensor " + String(i+1) + ":</div>";
    webPage += "<div class='sensor-bar'><div class='sensor-value' id='value" + String(i+1) + "'></div></div>";
    webPage += "<div>Raw: <span id='raw" + String(i+1) + "'>0</span>, ";
    webPage += "Processed: <span id='processed" + String(i+1) + "'>0</span></div>";
    webPage += "<div class='sensor-binary' id='binary" + String(i+1) + "'></div>";
    webPage += "</div>";
  }

  webPage += "</div>";
  webPage += "</div>";

  webPage += "<div id='status-tab' class='tab-content'>";
  webPage += "<h2>Status</h2>";
  webPage += "<div>On Line: <span id='onLine'>No</span></div>";
  webPage += "<div>Error: <span id='error'>0</span></div>";
  webPage += "<div>Left Speed: <span id='leftSpeed'>0</span></div>";
  webPage += "<div>Right Speed: <span id='rightSpeed'>0</span></div>";
  webPage += "</div>";

  webPage += "<div id='debug-tab' class='tab-content'>";
  webPage += "<h2>Debug Log</h2>";
  webPage += "<div class='debug-controls'>";
  webPage += "<a href='/clearlogs' class='button gray'>Clear Logs</a>";
  webPage += "</div>";
  webPage += "<div class='debug-log' id='debug-log'></div>";
  webPage += "</div>";

  webPage += "<script>";
  webPage += "function openTab(tabId) {";
  webPage += "  const tabs = document.getElementsByClassName('tab');";
  webPage += "  for (let i = 0; i < tabs.length; i++) {";
  webPage += "    tabs[i].classList.remove('active');";
  webPage += "  }";
  webPage += "  const tabContents = document.getElementsByClassName('tab-content');";
  webPage += "  for (let i = 0; i < tabContents.length; i++) {";
  webPage += "    tabContents[i].classList.remove('active');";
  webPage += "  }";
  webPage += "  document.getElementById(tabId).classList.add('active');";
  webPage += "  if (tabId === 'sensors-tab') {";
  webPage += "    document.getElementsByClassName('tab')[0].classList.add('active');";
  webPage += "  } else if (tabId === 'status-tab') {";
  webPage += "    document.getElementsByClassName('tab')[1].classList.add('active');";
  webPage += "  } else if (tabId === 'debug-tab') {";
  webPage += "    document.getElementsByClassName('tab')[2].classList.add('active');";
  webPage += "    updateDebugLog();";
  webPage += "  }";
  webPage += "}";

  webPage += "function updateSensors() {";
  webPage += "  fetch('/sensors')";
  webPage += "    .then(response => response.json())";
  webPage += "    .then(data => {";
  webPage += "      for (let i = 1; i <= " + String(numSensors) + "; i++) {";
  webPage += "        const sensor = data['sensor'+i];";
  webPage += "        document.getElementById('raw'+i).textContent = sensor.raw;";
  webPage += "        document.getElementById('processed'+i).textContent = sensor.processed;";
  webPage += "        document.getElementById('value'+i).style.width = (sensor.processed/10) + '%';";
  webPage += "        document.getElementById('binary'+i).style.backgroundColor = sensor.binary ? '#4CAF50' : '#f44336';";
  webPage += "      }";
  webPage += "    });";
  webPage += "}";

  webPage += "function updateDebugLog() {";
  webPage += "  fetch('/logs')";
  webPage += "    .then(response => response.text())";
  webPage += "    .then(data => {";
  webPage += "      const logElement = document.getElementById('debug-log');";
  webPage += "      logElement.textContent = data;";
  webPage += "      logElement.scrollTop = logElement.scrollHeight;";
  webPage += "    });";
  webPage += "}";

  webPage += "setInterval(updateSensors, 200);";
  webPage += "setInterval(() => {";
  webPage += "  if (document.getElementById('debug-tab').classList.contains('active')) {";
  webPage += "    updateDebugLog();";
  webPage += "  }";
  webPage += "}, 1000);";
  webPage += "</script>";
  webPage += "</body></html>";
}

void linefollow() {
  error = 0;
  activeSensors = 0;

  for (int i = 0; i < numSensors; i++) {
    error += sensorWeight[i] * sensorArray[i] * sensorValue[i];
    activeSensors += sensorArray[i];
  }

  if (activeSensors > 0) {
    error = error / activeSensors;
  }

  P = error;
  I = constrain(I + error, -100, 100);  // Add bounds to prevent integral windup
  D = error - previousError;

  PIDvalue = (Kp * P) + (Ki * I) + (Kd * D);
  previousError = error;

  lsp = currentSpeed - PIDvalue;
  rsp = currentSpeed + PIDvalue;

  lsp = constrain(lsp, 0, 255);
  rsp = constrain(rsp, 0, 255);

  motor1run(lsp);
  motor2run(rsp);
}

void calibrate() {
  logMessage("Starting calibration process...");

  // Initialize min/max values
  for (int i = 0; i < numSensors; i++) {
    minValues[i] = analogRead(i);
    maxValues[i] = analogRead(i);
  }

  // Calibration routine - turn in place while reading min/max values
  for (int i = 0; i < 3000; i++) {
    motor1run(50);
    motor2run(-50);

    for (int j = 0; j < numSensors; j++) {
      int value = analogRead(j);
      if (value < minValues[j]) {
        minValues[j] = value;
      }
      if (value > maxValues[j]) {
        maxValues[j] = value;
      }
    }
    delay(2);
  }

  // Calculate thresholds
  String thresholdValues = "Thresholds: ";
  for (int i = 0; i < numSensors; i++) {
    threshold[i] = (minValues[i] + maxValues[i]) / 2;
    thresholdValues += threshold[i];
    if (i < numSensors - 1) thresholdValues += ", ";
  }
  logMessage(thresholdValues);

  // Stop motors after calibration
  motor1run(0);
  motor2run(0);
  logMessage("Calibration complete");
}

void readLine() {
  onLine = 0;

  for (int i = 0; i < numSensors; i++) {
    int rawValue = analogRead(i);

    if (isBlackLine) {
      sensorValue[i] = map(rawValue, minValues[i], maxValues[i], 0, 1000);
    } else {
      sensorValue[i] = map(rawValue, minValues[i], maxValues[i], 1000, 0);
    }

    sensorValue[i] = constrain(sensorValue[i], 0, 1000);
    sensorArray[i] = sensorValue[i] > 500;

    if (sensorArray[i]) {
      onLine = 1;
    }
  }
}

//--------Function to run Motor 1-----------------
void motor1run(int motorSpeed) {
  motorSpeed = constrain(motorSpeed, -255, 255);
  if (motorSpeed > 0) {
    digitalWrite(AIN1, 1);
    digitalWrite(AIN2, 0);
    ledcWrite(0, motorSpeed);
  } else if (motorSpeed < 0) {
    digitalWrite(AIN1, 0);
    digitalWrite(AIN2, 1);
    ledcWrite(0, abs(motorSpeed));
  } else {
    digitalWrite(AIN1, 1);
    digitalWrite(AIN2, 1);
    ledcWrite(0, 0);
  }
}

//--------Function to run Motor 2-----------------
void motor2run(int motorSpeed) {
  motorSpeed = constrain(motorSpeed, -255, 255);
  if (motorSpeed > 0) {
    digitalWrite(BIN1, 1);
    digitalWrite(BIN2, 0);
    ledcWrite(1, motorSpeed);
  } else if (motorSpeed < 0) {
    digitalWrite(BIN1, 0);
    digitalWrite(BIN2, 1);
    ledcWrite(1, abs(motorSpeed));
  } else {
    digitalWrite(BIN1, 1);
    digitalWrite(BIN2, 1);
    ledcWrite(1, 0);
  }
}