1.3.2 Servo

Introduction

In this project, we will learn how to make the servo rotate.

Required Components

In this project, we need the following components.

Schematic Diagram

Experimental Procedures

Step 1: Build the circuit.

Step 2: Go to the folder of the code.

cd ~/davinci-kit-for-raspberry-pi/python-pi5

Step 3: Run the executable file.

sudo python3 1.3.2_Servo_zero.py

After the program is executed, the servo will rotate from 0 degrees to 90 to 180 degrees, and then from 180 degrees to 90 to 0 degrees, in a circle.

Code

Note

You can Modify/Reset/Copy/Run/Stop the code below. But before that, you need to go to source code path like davinci-kit-for-raspberry-pi/python-pi5. After modifying the code, you can run it directly to see the effect.

#!/usr/bin/env python3
from gpiozero import Servo
from time import sleep

# Set the GPIO pin number where the servo motor is connected
myGPIO = 18

# Define a correction factor to fine-tune servo pulse width
myCorrection = 0.45
maxPW = (2.0 + myCorrection) / 1000  # Calculate maximum pulse width
minPW = (1.0 - myCorrection) / 1000  # Calculate minimum pulse width

# Initialize the Servo object with custom pulse widths
servo = Servo(myGPIO, min_pulse_width=minPW, max_pulse_width=maxPW)

try:
    while True:
        # Position the servo at the middle and wait
        servo.mid()
        print("mid")  # Indicate current position
        sleep(0.5)    # Brief pause for 0.5 seconds

        # Move the servo to its minimum position and wait
        servo.min()
        print("min")  # Indicate current position
        sleep(1)      # Hold position for 1 second

        # Return the servo to the middle position and wait
        servo.mid()
        print("mid")  # Indicate current position
        sleep(0.5)    # Brief pause for 0.5 seconds

        # Move the servo to its maximum position and wait
        servo.max()
        print("max")  # Indicate current position
        sleep(1)      # Hold position for 1 second

except KeyboardInterrupt:
    # Gracefully terminate the script on a keyboard interrupt (Ctrl+C)
    pass

Code Explanation

1. These import statements bring in the Servo class for servo control and the sleep function for timing.

   #!/usr/bin/env python3
   from gpiozero import Servo
   from time import sleep
   

2. Sets the GPIO pin number 18 for connecting the servo motor.

   # Set the GPIO pin number where the servo motor is connected
   myGPIO = 18
   

3. These lines define a correction factor and use it to calculate the maximum and minimum pulse widths for the servo, fine-tuning its movement range.

   # Define a correction factor to fine-tune servo pulse width
   myCorrection = 0.45
   maxPW = (2.0 + myCorrection) / 1000  # Calculate maximum pulse width
   minPW = (1.0 - myCorrection) / 1000  # Calculate minimum pulse width
   

4. Initializes the Servo object with the specified GPIO pin and custom pulse widths.

   # Initialize the Servo object with custom pulse widths
   servo = Servo(myGPIO, min_pulse_width=minPW, max_pulse_width=maxPW)
   

5. The try block contains a while True loop to continuously move the servo. The servo is positioned at mid, min, and max points, with each position printed and held for a specified duration.

   try:
       while True:
           # Position the servo at the middle and wait
           servo.mid()
           print("mid")  # Indicate current position
           sleep(0.5)    # Brief pause for 0.5 seconds
   
           # Move the servo to its minimum position and wait
           servo.min()
           print("min")  # Indicate current position
           sleep(1)      # Hold position for 1 second
   
           # Return the servo to the middle position and wait
           servo.mid()
           print("mid")  # Indicate current position
           sleep(0.5)    # Brief pause for 0.5 seconds
   
           # Move the servo to its maximum position and wait
           servo.max()
           print("max")  # Indicate current position
           sleep(1)      # Hold position for 1 second
   
   except KeyboardInterrupt:
       # Gracefully terminate the script on a keyboard interrupt (Ctrl+C)
       pass