### Project 33 SR01 Ultrasonic Sensor

**1. Introduction**
The Keyestudio SR01 Ultrasonic Sensor is a very affordable proximity/distance sensor that has been used mainly for object avoidance in various robotics projects.

It essentially gives your Arduino eyes/spacial awareness and can prevent your robot from crashing or falling off a table. It has also been used in turret applications, water level sensing, and even as a parking sensor.

This simple project will use the Keyestudio SR01 Ultrasonic Sensor with an Arduino and a Processing sketch to provide a neat little interactive display on your computer screen.

![](media/image-20251121122016240.png)

**2. Specification**

- Working Voltage: DC 5V
- Working Current: 15mA
- Working Frequency: 40Hz
- Max Range: 5m
- Min Range: 2cm
- Measuring Angle: 15 degree
- Trigger Input Signal: 10µS TTL pulse
- Echo Output Signal Input TTL lever signal and the range in proportion

**3. Connection Diagram**

![](media/image-20251121122055700.png)

| SR01 Ultrasonic Sensor |      UNO      |
| :--------------------: | :-----------: |
|          VCC           |      5V       |
|          GND           |      GND      |
|          Echo          | Digital Pin 7 |
|          Trig          | Digital Pin 8 |

**4. Sample Code**

- VCC to arduino 5v
- GND to arduino GND
- Echo to Arduino pin 7
- Trig to Arduino pin 8

```c
#define echoPin 7 // Echo Pin
#define trigPin 8 // Trigger Pin
#define LEDPin 13 // Onboard LED

int maximumRange = 200; // Maximum range needed
int minimumRange = 0; // Minimum range needed
long duration, distance; // Duration used to calculate distance

void setup() 
{
 Serial.begin (9600);
 pinMode(trigPin, OUTPUT);
 pinMode(echoPin, INPUT);
 pinMode(LEDPin, OUTPUT); // Use LED indicator (if required)
}

void loop() 
{
  /* The following trigPin/echoPin cycle is used to determine the
  distance of the nearest object by bouncing soundwaves off of it. */ 
  digitalWrite(trigPin, LOW); 
  delayMicroseconds(2); 

  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10); 
  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH);
 
 //Calculate the distance (in cm) based on the speed of sound.
 distance = duration/58.2;
 
  if (distance >= maximumRange || distance <= minimumRange)
  {
      /* Send a negative number to computer and Turn LED ON 
      to indicate "out of range" */
      Serial.println("-1");
      digitalWrite(LEDPin, HIGH); 
  }
 else 
 {
     /* Send the distance to the computer using Serial protocol, and
     turn LED OFF to indicate successful reading. */
     Serial.println(distance);
     digitalWrite(LEDPin, LOW); 
 }
 //Delay 50ms before next reading.
 delay(50);
}
```

**5. Result**

![](media/111.png)

After upload the code to the board, open the serial monitor of Arduino IDE, you can see the distance value measured by ultrasonic sensor.

![](media/13.png)