Первые шаги.

/*
    This code should work to get warning cross the buzzer when something be closer than 0.5 meter
    Circuit is ultrasonic sensor and buzzer +5v and Arduino uno is used
    http://myrobotduino.blogspot.my/
*/
// Define pins for ultrasonic and buzzer
int const trigPin = 10;
int const echoPin = 9;
int const buzzPin = 2;

void setup()
{
    pinMode(trigPin, OUTPUT); // trig pin will have pulses output
    pinMode(echoPin, INPUT); // echo pin should be input to get pulse width
    pinMode(buzzPin, OUTPUT); // buzz pin is output to control buzzering

}

void loop()
{
    // Duration will be the input pulse width and distance will be the distance to the obstacle in centimeters
    int duration, distance;
    // Output pulse with 1ms width on trigPin
    digitalWrite(trigPin, HIGH); 
    delay(1);
    digitalWrite(trigPin, LOW);
    // Measure the pulse input in echo pin
    duration = pulseIn(echoPin, HIGH);
    // Distance is half the duration devided by 29.1 (from datasheet)
    distance = (duration/2) / 29.1;
    // if distance less than 0.5 meter and more than 0 (0 or less means over range) 
    if (distance <= 50 && distance >= 0) 
    {
        // Buzz
        digitalWrite(buzzPin, HIGH);
      tone (buzzPin, 800);
      delay(005);
     }
    else 
    {
        // Don't buzz
        digitalWrite(buzzPin, LOW);
      noTone(buzzPin);
     
     }
    // Waiting 60 ms won't hurt any one
    delay(10);
}

/*
    This code should work to get warning cross the buzzer when something be closer than 0.5 meter
    Circuit is ultrasonic sensor and buzzer +5v and Arduino uno is used
    http://myrobotduino.blogspot.my/
*/
// Define pins for ultrasonic and buzzer
int const trigPin = 10;
int const echoPin = 9;
int const buzzPin = 2;

void setup()
{
    pinMode(trigPin, OUTPUT); // trig pin will have pulses output
    pinMode(echoPin, INPUT); // echo pin should be input to get pulse width
    pinMode(buzzPin, OUTPUT); // buzz pin is output to control buzzering

}

void loop()
{
    // Duration will be the input pulse width and distance will be the distance to the obstacle in centimeters
    int duration, distance;
    // Output pulse with 1ms width on trigPin
    digitalWrite(trigPin, HIGH); 
    delay(1);
    digitalWrite(trigPin, LOW);
    // Measure the pulse input in echo pin
    duration = pulseIn(echoPin, HIGH);
    // Distance is half the duration devided by 29.1 (from datasheet)
    distance = (duration/2) / 29.1;
    // if distance less than 0.5 meter and more than 0 (0 or less means over range) 
    if (distance <= 50 && distance >= 0) 
    {
        // Buzz
        digitalWrite(buzzPin, HIGH);
      
     }
    else 
    {
        // Don't buzz
        digitalWrite(buzzPin, LOW);
        
    }
    // Waiting 60 ms won't hurt any one
    delay(10);
}