Ultrasonic Sensor

Measure distance between ultrasonic sensor and object

Since R2022b

• 

Libraries:
Raspberry Pi Blockset / 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 (Simulink).

Note

To generate code C/C++ code for this block, you must have an Embedded Coder^® license.

Ports

Output

Distance — 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

Board — Board to connect the ultrasonic sensor

Pi 4 Model B (default) | Model B Rev1 | Model B Rev2 | Model B+ | Pi 2 Model B | Pi 3 Model B | Pi 3 Model B+ | Pi Zero W | Compute Module 4 | Pi Zero 2 W | Pi 5 Model

Select the Raspberry Pi^® hardware board to which the ultrasonic sensor is connected. For information about the digital pin numbers on the hardware, click View pin map.

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

2 (default) | 1

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

GPIO 23 (default) | GPIO 4 | GPIO 17 | GPIO 27 | GPIO 22 | GPIO 10 | GPIO 9 | GPIO 11 | GPIO 14 | GPIO 15 | GPIO 18 | GPIO 24 | GPIO 25 | GPIO 8 | GPIO 7

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 View pin map.

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

GPIO 24 (default) | GPIO 4 | GPIO 17 | GPIO 27 | GPIO 22 | GPIO 10 | GPIO 9 | GPIO 11 | GPIO 14 | GPIO 15 | GPIO 18 | GPIO 23 | GPIO 25 | GPIO 8 | GPIO 7

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 View pin map.

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

GPIO 23 (default) | GPIO 4 | GPIO 17 | GPIO 27 | GPIO 22 | GPIO 10 | GPIO 9 | GPIO 11 | GPIO 14 | GPIO 15 | GPIO 18 | GPIO 24 | GPIO 25 | GPIO 8 | GPIO 7

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 View pin map.

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 0.000301 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.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using Simulink® Coder™.

To generate code C/C++ code for this block, you must have an Embedded Coder license. For more information on selecting the right product stack according to your development goals, see Product Stack for Raspberry Pi Blockset.

Version History

Introduced in R2022b