/************************************************************
  LEAN STATION - Cycle Time Monitoring System
  Board: Seeed Studio XIAO ESP32-C3
  Sensor: HC-SR04 Ultrasonic Sensor
  Platform: Blynk IoT

  Description:
  This program detects when an object passes through the sensing
  area of a conveyor belt, measures the cycle time, counts the
  number of cycles, calculates the average time, and sends the
  information to a Blynk dashboard.

  Author: Rodrigo Guamán
************************************************************/


/************************************************************
  1. Blynk and WiFi Configuration
************************************************************/

#define BLYNK_TEMPLATE_ID "TMPL2_cwfk2-a"
#define BLYNK_TEMPLATE_NAME "LEAN STATION"
#define BLYNK_AUTH_TOKEN "PASTE_YOUR_BLYNK_AUTH_TOKEN_HERE"

#include <WiFi.h>
#include <WiFiClient.h>
#include <BlynkSimpleEsp32.h>

// Replace these values with your own WiFi credentials
char ssid[] = "YOUR_WIFI_SSID";
char pass[] = "YOUR_WIFI_PASSWORD";


/************************************************************
  2. Sensor Pins and Process Variables
************************************************************/

// HC-SR04 sensor pins
#define TRIG_PIN D5
#define ECHO_PIN D6

// Detection threshold in centimeters
float detectionThreshold = 15.0;

// Distance and detection states
float distanceCM = 0;
bool objectDetected = false;
bool previousState = false;

// Cycle time variables
unsigned long startTime = 0;
float cycleTime = 0;
float totalTime = 0;
float averageTime = 0;
int cycleCount = 0;

// Optional variable for dashboard
float cyclesPerMinute = 0;

// Blynk timer
BlynkTimer timer;


/************************************************************
  3. Distance Reading Function
************************************************************/

float readDistance() {
  // Send ultrasonic pulse
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);

  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);

  digitalWrite(TRIG_PIN, LOW);

  // Read echo time
  long duration = pulseIn(ECHO_PIN, HIGH, 30000);

  // If no echo is received, return a large value
  if (duration == 0) {
    return 999;
  }

  // Convert time into distance in centimeters
  float distance = duration * 0.0343 / 2.0;

  return distance;
}


/************************************************************
  4. Object Detection and Cycle Measurement
************************************************************/

void monitorProcess() {
  // Read distance from ultrasonic sensor
  distanceCM = readDistance();

  // Send distance value to Blynk
  Blynk.virtualWrite(V5, distanceCM);

  // Object is detected when the distance is below the threshold
  objectDetected = distanceCM < detectionThreshold;

  // Detect transition: free area to object present
  if (objectDetected == true && previousState == false) {
    startTime = millis();

    Blynk.virtualWrite(V3, "Object detected");
    Serial.println("Object detected");
  }

  // Detect transition: object present to free area
  if (objectDetected == false && previousState == true) {
    cycleTime = (millis() - startTime) / 1000.0;

    cycleCount++;
    totalTime += cycleTime;
    averageTime = totalTime / cycleCount;

    // Calculate cycles per minute based on the last cycle
    if (cycleTime > 0) {
      cyclesPerMinute = 60.0 / cycleTime;
    }

    // Send values to Blynk dashboard
    Blynk.virtualWrite(V0, cycleCount);
    Blynk.virtualWrite(V1, cycleTime);
    Blynk.virtualWrite(V2, averageTime);
    Blynk.virtualWrite(V3, "Area free");
    Blynk.virtualWrite(V4, cyclesPerMinute);

    // Print values in Serial Monitor
    Serial.println("-------------------------");
    Serial.print("Cycle Count: ");
    Serial.println(cycleCount);

    Serial.print("Cycle Time: ");
    Serial.print(cycleTime);
    Serial.println(" s");

    Serial.print("Average Time: ");
    Serial.print(averageTime);
    Serial.println(" s");

    Serial.print("Cycles per Minute: ");
    Serial.println(cyclesPerMinute);
    Serial.println("-------------------------");
  }

  // Update previous state
  previousState = objectDetected;
}


/************************************************************
  5. Reset Button from Blynk
************************************************************/

BLYNK_WRITE(V6) {
  if (param.asInt() == 1) {
    cycleCount = 0;
    cyclesPerMinute = 0;
    totalTime = 0;
    averageTime = 0;
    cycleTime = 0;
    startTime = 0;

    // Update dashboard values
    Blynk.virtualWrite(V0, cycleCount);
    Blynk.virtualWrite(V1, cycleTime);
    Blynk.virtualWrite(V2, averageTime);
    Blynk.virtualWrite(V3, "Data reset");
    Blynk.virtualWrite(V4, cyclesPerMinute);
    Blynk.virtualWrite(V5, distanceCM);

    Serial.println("Data reset from Blynk button");
  }
}


/************************************************************
  6. Setup Function
************************************************************/

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

  // Configure ultrasonic sensor pins
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);

  // Start Blynk connection
  Blynk.begin(BLYNK_AUTH_TOKEN, ssid, pass);

  // Run monitoring function every 200 ms
  timer.setInterval(200L, monitorProcess);

  Serial.println("LEAN STATION started");
}


/************************************************************
  7. Main Loop
************************************************************/

void loop() {
  Blynk.run();
  timer.run();
}