#define TRIGGER_PIN 13
#define ECHO_PIN 12
#define PWM_PIN 5
#define POTI_PIN 4

unsigned int max_distance;
int poti;
int out;

void trigger_pulse() {
    digitalWrite(TRIGGER_PIN, HIGH);
    delayMicroseconds(10);
    digitalWrite(TRIGGER_PIN, LOW);
}

void setup() {
    Serial.begin(115200); // Starts the serial communication
    pinMode(TRIGGER_PIN, OUTPUT); // Trigger pin as output
    pinMode(ECHO_PIN, INPUT); // Echo pin as input
    pinMode(PWM_PIN, OUTPUT); // PWM pin as output
    pinMode(POTI_PIN, INPUT); // Potentiometer pin as input

    
    
    //analogWrite(PWM_PIN, 0); // Initial PWM duty cycle
}

void loop() {
    max_distance = map(analogRead(POTI_PIN), 0, 4095, 0, 400); // Read max distance from potentiometer
    trigger_pulse();
    while(!digitalRead(ECHO_PIN)); // Wait for echo to go high
    unsigned long start = micros(); // Record start time
    while(digitalRead(ECHO_PIN)); // Wait for echo to go low
    unsigned long duration = micros() - start; // Measure duration of echo pulse
    unsigned int distance = duration / 58.2; // Calculate distance in cm
    distance = constrain(distance, 0, max_distance); // Constrain distance to max distance
    analogWrite(PWM_PIN, map(distance, 0, max_distance, 255, 0)); // Set PWM duty cycle based on distance
    out = map(distance, 0, max_distance, 255, 0);
    poti = analogRead(POTI_PIN);
   Serial.print("distance: ");
   Serial.print(distance);
   Serial.print("   out: ");
   Serial.print(out);
   Serial.print("   poti: ");
   Serial.print(poti);
   Serial.print("   max_distance: ");
   Serial.println(max_distance);

   delay(500);


}