Chapter 16 Servo

Previously, we learned how to control the speed and rotational direction of a mo tor. In this chapter, we will learn about servos which are a rotary actuator ty pe motor that can be controlled to rotate to specific angles.

Project 16.1 Servo Sweep

First, we need to learn how to make a servo rotate.

Component List

ESP32-S3-WROOM x1
GPIO Extension Board x1
830 Tie-Points Breadboard x1
Servo x1
Jumper Wire x3

Connect

Use caution when supplying power to the servo, it should be 5V. Make sure you do not make any errors when connecting the servo to the power supply.

Code

Move the program folder Super_Starter_Kit_for_ESP32_S3/Python/Python_Codes to disk(D) in advance with the path of “D:/Micropython_Codes”.

Open “Thonny”, click This computer/D:/Micropython_Codes/16.1_Servo_Sweep. Select “myservo.py”, right click your mouse to select “Upload to /”, wait for “myservo.py” to be uploaded to ESP32-S3 and then double click “Servo_Sweep.py”.

16.1_Servo_Sweep

Click “Run current script”, the Servo will rotate from 0 degrees to 180 degrees and then reverse the direction to make it rotate from 180 degrees to 0 degrees and repeat these actions in an endless loop.

Code

The following is the program code:

from myservo import myServo
import time

servo=myServo(21)#set servo pin
servo.myServoWriteAngle(0)#Set Servo Angle
time.sleep_ms(1000)

try:
    while True:
        for i in range(0,180,1):
            servo.myServoWriteAngle(i)
            time.sleep_ms(15)
        for i in range(180,0,-1):
            servo.myServoWriteAngle(i)
            time.sleep_ms(15)
except:
    servo.deinit()

Project 16.2 Servo Knop

Use a potentiometer to control the servo motor to rotate at any angle.

Component List

ESP32-S3-WROOM x1
GPIO Extension Board x1
830 Tie-Points Breadboard x1
Servo x1
Potentiometer(10k) x1
Jumper Wire x6

Connect

Use caution when supplying power to the servo, it should be 5V. Make sure you do not make any errors when connecting the servo to the power supply.

Code

Move the program folder Super_Starter_Kit_for_ESP32_S3/Python/Python_Codes to disk(D) in advance with the path of “D:/Micropython_Codes”.

Open “Thonny”, click This computer/D:/Micropython_Codes/16.2_Servo_Knop. Select “myservo.py”, right click your mouse to select “Upload to /”, wait for “myservo.py” to be uploaded to ESP32S3 and then double click “Servo_Knop.py”.

16.2_Servo_Knop

Click “Run current script”, twist the potentiometer back and forth, and the servo motor rotates accordingly.

Code

The following is the program code:

from myservo import myServo
from machine import ADC,Pin
import time

servo=myServo(21)

adc2=ADC(Pin(14))
adc2.atten(ADC.ATTN_11DB)
adc2.width(ADC.WIDTH_12BIT)

try:
    while True:
        adcValue=adc2.read()
        angle=(adcValue*180)/4096
        servo.myServoWriteAngle(int(angle))
        time.sleep_ms(50)
except:
    servo.deinit()

In this project, we will use Pin(14) of ESP32-S3 to read the ADC value of the rotary potentiometer and then convert it to the angle value required by the servo and control the servo to rotate to the corresponding angle.