Smart Bridge - According to water level Best science Project.

 

.......................Diagram......................

...................Arduino Code.....................

//YouTube Harish Projects 

#include <Servo.h>

// constants won't change

const int TRIG_PIN  = 6;  // Arduino pin connected to Ultrasonic Sensor's TRIG pin

const int ECHO_PIN  = 7;  // Arduino pin connected to Ultrasonic Sensor's ECHO pin

const int SERVO_PIN = 9; // Arduino pin connected to Servo Motor's pin

const int DISTANCE_THRESHOLD = 4; // centimeters

Servo servo; // create servo object to control a servo

// variables will change:

float duration_us, distance_cm;

void setup() {

  Serial.begin (9600);       // initialize serial port

  pinMode(TRIG_PIN, OUTPUT); // set arduino pin to output mode

  pinMode(ECHO_PIN, INPUT);  // set arduino pin to input mode

  servo.attach(SERVO_PIN);   // attaches the servo on pin 9 to the servo object

  servo.write(0);

}

void loop() {

  // generate 10-microsecond pulse to TRIG pin

  digitalWrite(TRIG_PIN, HIGH);

  delayMicroseconds(200);

  digitalWrite(TRIG_PIN, LOW);

  // measure duration of pulse from ECHO pin

  duration_us = pulseIn(ECHO_PIN, HIGH);

  // calculate the distance

  distance_cm = 0.017 * duration_us;

  if(distance_cm < DISTANCE_THRESHOLD)

    servo.write(90); // rotate servo motor to 90 degree

  else

    servo.write(0);  // rotate servo motor to 0 degree

  // print the value to Serial Monitor

  Serial.print("distance: ");

  Serial.print(distance_cm);

  Serial.println(" cm");

  delay(3000);

}