Ultrasonic¶

Class Ultrasonic is a subclass of EV3. You can use it to read values from a single ultrasonic sensor without any knowledge of direct command syntax.

The ultrasonic sensor sends and receives ultrasonic sound signals. It is able to calculate distances by analyzing reflected sound. This is a subset of the infrared sensors functionality,

The ultrasonic sensor returns a distance of 2.55 m, when it does not detect anything. Class Ultrasonic replaces this by value None.

If you like to use multiple ultrasonic sensors simultaneously, you can create more than one instance of this class.

Asking for the distance from a surface¶

Class Ultrasonic has an attribute distance, which is of type float and tells, if the the sensor currently sees some surface in front and in a distance closer than 2.55 m.

Take an USB cable and connect your EV3 device with your computer. Replace MAC-address 00:16:53:42:2B:99 by the one of your EV3 brick, connect an ultrasonic sensor (it may be of type ev3.NXT_ULTRASONIC or ev3.EV3_ULTRASONIC) with PORT 3, then start this program:

from time import sleep
import ev3_dc as ev3

my_ultrasonic = ev3.Ultrasonic(
        ev3.PORT_3,
        protocol=ev3.USB,
        host='00:16:53:42:2B:99'
)

while True:
    dist = my_ultrasonic.distance
    if dist:
        break
    sleep(0.1)

print(f'something seen {dist:3.2f} m ahead')

Some remarks:

You already know, how to change the program for using protocols Bluetooth or WiFi.

Run the program multiple times with different surfaces and distances.

Test what happens, when no sensor is connected to PORT 2.

Test what happens, when another sensor type is connected to PORT 2.

Test for the maximum distance and determine if this depends on the surface material.

Every reference of property distance starts a new communication between the program and the EV3 device.

Switch on verbosity by setting attribute verbosity to value 1 and you will see the communication data.