2.11 Reversing System

For this project we used an ultrasonic module and an active buzzer to create a reversing alarm system. The ultrasonic module is used to detect the distance, and the buzzer emits different frequencies of alarm sounds depending on the distance.



  • The Echo and Trig pins of the ultrasonic module are connected to GP15 at the same time, so that the ultrasonic module sends and receives signals from GP15.

  • The middle pin of the transistor connected to the buzzer is connected to GP14 through a 1kΩ resistor.



  • You can refer to the image below to write code by dragging and dropping.

  • Import 2.11_reversing_system.png from the path of euler-kit\piper. For detailed tutorials, please refer to Import the Code.


  • After connecting Pico, click the Start button and the code starts to run.

  • When the ultrasonic detection distance is less than 5cm, the buzzer emits a sharp sound (0.1s).

  • When the detection distance is between 5~10cm, the buzzer emits a slightly slow sound (0.5s).

  • When the detection distance is greater than 10cm, there is a sound prompt every 1 second.

How it Works?


Read the distance (in cm) of the ultrasonic detection, and store it in the variable [distance].


When distance is less than or equal to 5, set the variable intervals to 0.1s. The variable [intervals] is the interval between buzzer sounds.


When distance is greater than 5 and less than or equal to 10, set the [intervals] to 0.5s.


When distance is greater than 10, set the [intervals] time to 1s.


Finally, make the buzzer sound every [intervals] seconds.