Purpose: Enable students to connect a servo motor to the CPX and control its movement based on sensors such as light or temperature.

Exercise:1

---

Servo Control Using CPX Toggle Switch

Click here to view the connection diagram for a servo motor and CPX
Click here to view the instructions and code

Exercise:2

---

Using Try-Except block in CircuitPython

Click here to view the instructions and code

Exercise:3

---

Handling Servo Motor Errors Using Try-Except in CircuitPython

Sample code:

Click here to view the instructions and code (without try-except)

How to fix the error:

Click here to view the instructions and code (with try-except)

Solution

---

Here is the solution:

Click here to see the solution video for Exercise 1
Click here to see the solution video for Exercise 3 (without try-except)
Click here to see the solution video for Exercise 3 (with try-except)

1. Explain about servo motors and PWM (Pulse Width Modulation) - explanation and diagram
2. Introduce the required materials (CPX, USB cable, Mu Editor, servo motor – 180°).
3. Simple Explanation:
   • Introduce students to different types of servos - 90, 180 and continuous servo motors and highlight how they are different
   • Teach students that a 180 servo motor moves only between 0° and 180°.
   • Show how to control the servo using CircuitPython and the servo.angle command.
   • Explain that setting angles in a 180 server outside the range, like 360° will cause an error.
   • Use a try–except block to safely handle invalid angles.
   • Students run the code and observe servo movements and REPL (Read, Evaluate, Print, Loop) messages.
   • Provide step-by-step instructions and demonstrate troubleshooting techniques.
4. View the code here
   What is the value of final_state in this? Talk about the motor_on=False statement inside the try-except block, why it is not reachable and different ways to ensure it executes
5. Is it better to prevent errors or handle them when they happen?