Ultrasonic Sensor - RoboCon Oxfordshire Docs

Ultrasonic sensors can be used for calculating the distance from a sensor to the nearest solid object. They do this through emitting a pulse of ultrasonic sound and recording the time taken for the echo to return. We can control ultrasonic sensors through GPIO on the Brain Box.

Python

You can create an ultrasonic sensor through creating an UltrasonicSensor object. The arguments to the initialisation function are first the trigger pin, followed by the echo pin. For example this configures a sensor with trigger on GPIO0 and echo on GPIO1.

sensor = robot.UltrasonicSensor(R.gpio[0], R.gpio[1])

We can then read the value of this sensor through calling the read() function which returns a distance in meters.

distance = sensor.read()

Here’s a complete example:

import robot

r = robot.Robot()

sensor = robot.UltrasonicSensor(r.gpio[0], r.gpio[1])
distance = sensor.read()

I want to use more than one ultrasound sensor but don’t have enough GPIO

The BrainBox can support (theoretically) up to 7 ultrasonic sensors. We do this through daisy-chaining the echo pin of one sensor to the trigger pin of another. For example for two sensors, sensor A has trigger pin GPIO0, and echo GPIO1, and sensor B has trigger pin GPIO1 and echo GPIO2. You can create an ultrasonic sensor combining these two physical sensors, by listing the echo pins in order.

sensors = robot.UltrasonicSensor(r.gpio[0], r.gpio[1], r.gpio[2])

If the echo pins are listed in the wrong order incorrect values may be returned