037 - MicroPython TechNotes: Servo Motor

Introduction

In this article, I will talk about SERVO MOTOR with ESP32 using MicroPython.

Bill Of Materials

1. ESP32 development board.
2. Gorillacell ESP32 shield.
3. Servo Motor

Pinout

1. brown wire – for the ground pin.
2. red wire – for the servo motor supply voltage.
3. orange wire – for the servo motor control signal.

Hardware Instruction

1. First, attach the ESP32 board on top of the GorillaCell ESP32 shield and make sure that both USB ports are on the same side.
2. Next, attach the servo motor wires to ESP32 shield by the following color coding:
   • servo motor brown wire – shield black pin headers.
   • servo motor red wire – shield red pin headers.
   • servo motor orange wire – shield yellow pin headers.
     For this lesson, I choose GPIO 25 to serve as the control signal pin to the servo motor.
3. Next, power the GorillaCell ESP32 shield with an external 5V power supply with a type-USB connector.
4. Last, connect the ESP32 to the computer through a micro-USB cable.

Software Instruction

For the software part, copy the sample program from the SOURCE CODE section.

You may modify and adapt it according to your needs, and most of all enjoy.

Video Demonstration

Call To Action

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Source Code

1. Example # 1, exploring the basics of controlling a servo motor:

 1# More details can be found in TechToTinker.blogspot.com 
 2# George Bantique | tech.to.tinker@gmail.com
 3
 4from machine import Pin
 5from machine import PWM
 6from time import sleep_ms
 7
 8def map(x, in_min, in_max, out_min, out_max):
 9    return int((x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min)
10    
11class GORILLACELL_SERVO:
12    def __init__(self, signal_pin):
13        self.pwm = PWM(Pin(signal_pin), freq=50, duty=0)
14
15    def rotate(self, angle):
16        self.pwm.duty(map(angle, 0, 180, 23, 124))
17        
18
19servo = GORILLACELL_SERVO(signal_pin=25)
20
21# The following lines of codes can be tested using the REPL:
22# # To rotate the servo motor to 0 degrees
23# servo.rotate(0)
24# 
25# # To rotate the servo motor to 90 degrees
26# servo.rotate(90)
27# 
28# # To rotate the servo motor to 180 degrees
29# servo.rotate(180)
30# 
31# # To rotate the servo from 0 to 180 degrees
32# # by 10 degrees increment
33# for angle in range(0, 181, 10):
34#     servo.rotate(angle)
35#     print(angle)
36#     sleep_ms(500)
37# # To rotate the servo from 180 to 0 degrees
38# # by 10 degrees decrement
39# for angle in range(180, -1, -10):
40#     servo.rotate(angle)
41#     print(angle)
42#     sleep_ms(500)

References And Credits

1. Purchase your Gorillacell ESP32 development kit at: https://gorillacell.kr

2. MG90S Timing diagram from: https://components101.com/motors/mg90s-metal-gear-servo-motor