Ultrasonic Sensor

Measure distance between ultrasonic sensor and object

• Library:

• Simulink Support Package for Arduino Hardware / Sensors

• 

Description

The Ultrasonic Sensor block outputs the distance between the ultrasonic sensor connected to the hardware and the nearest object in front of the sensor. The block outputs the distance as a double-precision value, in meters. If the object is placed beyond the range of sensor detection, the block outputs 0.

If you simulate a model that contains the Ultrasonic Sensor block without connecting the hardware, the block outputs zeros. For more information, see Block Produces Zeros or Does Nothing in Simulation.

Ports

Output

Port_1 — Distance between ultrasonic sensor and nearest object in front of sensor

scalar

The port outputs the distance between the ultrasonic sensor connected to the hardware and the nearest object in front of the sensor. The block outputs the distance in meters. If the object is placed beyond the range of sensor detection, the port outputs 0.

Data Types: double

Parameters

Number of signal pins — Number of signal pins on ultrasonic sensor

1 (default) | 2

Select the number of signal pins on the ultrasonic sensor to send and receive sound waves.

• 1 — If the ultrasonic sensor has only one signal pin, SIG, select 1.

• 2 — If the ultrasonic sensor has two separate signal pins, Trig and Echo, select 2.

Trigger pin — Digital pin connected to Trig pin

4 (default) | any valid pin number

Select the digital pin on the hardware to which the Trig pin of the ultrasonic sensor is connected. For information about the digital pin numbers on the hardware, click Arduino Pin Mapping for Timer Independent Blocks.

Dependencies

The Trigger pin parameter appears only when you set the Number of signal pins parameter to 2.

Echo pin — Digital pin connected to Echo pin

5 (default) | any valid pin number

Select the digital pin on the hardware to which the Echo pin of the ultrasonic sensor is connected. For information about the digital pin numbers on the hardware, click Pin Mapping on Arduino Blocks.

Dependencies

The Echo pin parameter appears only when you set the Number of signal pins parameter to 2.

Signal pin — Digital pin connected to SIG pin

3 (default) | any valid pin number

Select the digital pin on the hardware to which the SIG pin of the ultrasonic sensor is connected. For information about the digital pin numbers on the hardware, click the View pin map button.

Dependencies

The Signal pin parameter appears only when you set the Number of signal pins parameter to 1.

Sample time — Interval to read distance using ultrasonic sensor

0.1 (default) | -1 | any nonnegative value

Specify how often the block reads distance using the ultrasonic sensor, measured in seconds.

When specifying Sample time, verify these settings to avoid task overrun:

1. The Sample time parameter must be equal to the model base rate. To view the model base rate, select Display > Sample Time > All on the model toolbar. In the Sample Time Legend dialog box, the value corresponding to the red box is the base rate of the model.

   

2. The Sample time parameter and the model base rate must be greater than the total time required by the sensor to transmit and receive the sound wave. For example, if the object is placed 0.1 meters away from the sensor, the Sample time parameter specified must be greater than 3.01 seconds.

   For information on how to calculate the travel time of the sound wave, see Calculate Travel Time of Sound Wave.

More About

Calculate Travel Time of Sound Wave

In this example, the object is 0.1 meters away from the sensor.

Calculate the travel time (T) of the sound wave using the formula:

T = D / S, where D is the distance between the sensor and the object. S is the speed of sound in air, which is approximately 332 meters per second (m/s). In this example, as the object is placed 0.1 m away from the sensor:

= 0.1 / 332

= 0.000301 seconds

The Sample time parameter specified must be greater than 0.000301 seconds.