tscinbunyTutorial/ESP32S3-Tutorial/example/Lesson_9_Steering_gear_control

9.Servo control

9.1. Overview

In this section, you will learn how to drive the servo to achieve 0~180° rotation.

9.2 Working principle

9.2.1. Steering gear

The steering gear ( servo motor ) control pulse signal period is a 20MS pulse width modulation signal (PWM), the pulse width is from 0.5ms to 2.5ms, and the corresponding steering position changes linearly from 0 to 180 degrees. There is a reference circuit inside the steering gear, which generates a pulse signal with a period of 20ms and a width of 1.5ms. There is a comparator that compares the external signal with the reference signal to determine the direction and size, thereby generating a motor rotation signal.

9.3 Connection lines

9.4 Upload code program

9.4.1 Connect the main control SD board to the computer using a USB cable

9.4.2 Open the program file (path: 2_ESP32_S3_PLUS\Lesson_9_Steering_gear_control)

Also select the board type as ESP32S3 Dev Module and select the COM number newly displayed when the USB is plugged in . Then click "Upload" to start compiling and uploading the program to the main control board, and wait for the program upload to be completed .

9.5 Code analysis

Declare the servo library Servo, define the servo pin A0 and instantiate the servo object myServo.

#include <ESP32Servo.h>

#define SERVO_PIN 9  // Connect the servo signal line to A0 of UNOR4 MINIMA
Servo myServo;        // Instantiate a steering gear object

Set the servo pin to output mode and initialize the servo.

void setup() {
  pinMode(SERVO_PIN, OUTPUT);  // Set the servo connected pin to output mode
  myServo.attach(SERVO_PIN);   // Set the steering gear object
}

Let the servo rotate back and forth between 0~180° in the loop function.

void loop() {
  // Let the steering gear turn from 180 to 0 degrees
  for (int angle = 180; angle >= 0; angle--) {
    myServo.write(angle);
    delay(10);
  }

  // Let the steering gear turn from 0 to 180 degrees
  for (int angle = 0; angle <= 180; angle++) {
    myServo.write(angle);
    delay(10);
  }
}