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ESP32 - Joystick - Servo Motor
In this tutorial, we are going to learn how to use ESP32 and a joystick to control two servo motors or a pan-tilt kit with servos.
A joystick has two built-in potentiometers square with each other (called X-axis and Y-axis). These potentiometers output the analog values (called X-value and Y-value) on VRX and VRY pins. We will use these analog values to control two servo motors independently: X-value controls servo #1 and Y-value controls servo #2. In the case of the pan-tilt kit, the movement of two servo motors creates 3-D movement.
There are two application use cases:
- Use case 1: The servo motors rotate according to the movement of the joystick's thump:
- The angles of servo motors are in proportion to the values of the joystick's X-value and Y-value.
- When we release the joystick's thump ⇒ all values returns back to the center values ⇒ servo motors automatically returns back to the center position
- Use case 2: use the joystick to command servo motors (up/down/left/right commands)
- When joystick's thump is pushed to the left, move the servo motor #1 in a clockwise direction step-by-step
- When joystick's thump is pushed to the right, move the servo motor #1 in an anti-clockwise direction step-by-step
- When joystick's thump is pushed up, move the servo motor #2 in clockwise direction step-by-step
- When joystick's thump is pushed down, move the servo motor #2 in an anti-clockwise direction step-by-step
- When we release the joystick's thump ⇒ the servo motors will not return to the center position
- If the joystick is pressed (push button), The servo motors will return to the center position
- If this is the first time you use ESP32, see how to setup environment for ESP32 on Arduino IDE.
- Do the wiring as above image.
- Connect the ESP32 board to your PC via a micro USB cable
- Open Arduino IDE on your PC.
- Select the right ESP32 board (e.g. ESP32 Dev Module) and COM port.
- Click to the Libraries icon on the left bar of the Arduino IDE.
- Type ServoESP32 on the search box, then look for the servo library by Jaroslav Paral. Please be aware that both version 1.1.1 and 1.1.0 are affected by bugs. Kindly choose a different version.
- Click Install button to install servo motor library for ESP32.
- Copy the above code and open with Arduino IDE
- Click Upload button on Arduino IDE to upload code to ESP32
- Open Serial Monitor
- Push the joystick in some direction
- See the servo motor's rotation
- See the result on Serial Monitor
- On Arduino IDE, Go to Tools Manage Libraries
- Search “ezButton”, then find the button library by ESP32GetStarted.com
- Click Install button to install ezButton library.
- Copy the above code and open with Arduino IDE
- Click Upload button on Arduino IDE to upload code to ESP32
- Open Serial Monitor
- Push the joystick in some direction
- See the servo motor's rotation
- See the result on Serial Monitor
We will explore the code for both use cases in the next parts.
Hardware Used In This Tutorial
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Introduction to Joystick and Servo Motor
If you do not know about joystick and servo motor (pinout, how it works, how to program ...), learn about them in the following tutorials:
Wiring Diagram
This image is created using Fritzing. Click to enlarge image
If you're unfamiliar with how to supply power to the ESP32 and other components, you can find guidance in the following tutorial: How to Power ESP32.
ESP32 Code
ESP32 Code - The servo motors rotate according to the movement of the joystick's thump
/*
* This ESP32 code is created by esp32io.com
*
* This ESP32 code is released in the public domain
*
* For more detail (instruction and wiring diagram), visit https://esp32io.com/tutorials/esp32-joystick-servo-motor
*/
#include <Servo.h>
#define VRX_PIN 36 // ESP32 pin GPIO36 (ADC0) connected to VRX pin
#define VRY_PIN 39 // ESP32 pin GPIO39 (ADC0) connected to VRY pin
#define SERVO_X_PIN 33 // ESP32 pin GPIO33 connected to Servo motor 1
#define SERVO_Y_PIN 26 // ESP32 pin GPIO26 connected to Servo motor 2
Servo xServo; // create servo object to control a servo 1
Servo yServo; // create servo object to control a servo 2
void setup() {
Serial.begin(9600) ;
xServo.attach(SERVO_X_PIN);
yServo.attach(SERVO_Y_PIN);
}
void loop() {
// read X and Y analog values
int valueX = analogRead(VRX_PIN);
int valueY = analogRead(VRY_PIN);
int xAngle = map(valueX, 0, 4095, 0, 180); // scale it to the servo's angle (0 to 180)
int yAngle = map(valueY, 0, 4095, 0, 180); // scale it to the servo's angle (0 to 180)
xServo.write(xAngle); // rotate servo motor 1
yServo.write(yAngle); // rotate servo motor 2
// print data to Serial Monitor on Arduino IDE
Serial.print("Joystick: ");
Serial.print(valueX);
Serial.print(", ");
Serial.print(valueY);
Serial.print(" => Servo Motor: ");
Serial.print(xAngle);
Serial.print("°, ");
Serial.print(yAngle);
Serial.println("°");
}
Quick Instructions
COM6
Coming soon
Autoscroll
Clear output
9600 baud
Newline
ESP32 Code - Use the joystick to command servo motors
/*
* This ESP32 code is created by esp32io.com
*
* This ESP32 code is released in the public domain
*
* For more detail (instruction and wiring diagram), visit https://esp32io.com/tutorials/esp32-joystick-servo-motor
*/
#include <Servo.h>
#include <ezButton.h>
#define VRX_PIN 36 // ESP32 pin GPIO36 (ADC0) connected to VRX pin
#define VRY_PIN 39 // ESP32 pin GPIO39 (ADC0) connected to VRY pin
#define SW_PIN 17 // ESP32 pin GPIO17 connected to SW pin
#define SERVO_X_PIN 33 // ESP32 pin GPIO33 connected to Servo motor 1
#define SERVO_Y_PIN 26 // ESP32 pin GPIO26 connected to Servo motor 2
#define COMMAND_NO 0x00
#define COMMAND_LEFT 0x01
#define COMMAND_RIGHT 0x02
#define COMMAND_UP 0x04
#define COMMAND_DOWN 0x08
#define LEFT_THRESHOLD 1000
#define RIGHT_THRESHOLD 3000
#define UP_THRESHOLD 1000
#define DOWN_THRESHOLD 3000
#define UPDATE_INTERVAL 100 // 100ms
ezButton button(SW_PIN);
Servo xServo; // create servo object to control a servo 1
Servo yServo; // create servo object to control a servo 2
int valueX = 0 ; // to store the X-axis value
int valueY = 0 ; // to store the Y-axis value
int xAngle = 90; // the center position of servo #1
int yAngle = 90; // the center position of servo #2
int command = COMMAND_NO;
unsigned long lastUpdateTime = 0;
void setup() {
Serial.begin(9600) ;
xServo.attach(SERVO_X_PIN);
yServo.attach(SERVO_Y_PIN);
button.setDebounceTime(50); // set debounce time to 50 milliseconds
}
void loop() {
button.loop(); // MUST call the loop() function first
if (millis() - lastUpdateTime > UPDATE_INTERVAL) {
lastUpdateTime = millis() ;
// read X and Y analog values
valueX = analogRead(VRX_PIN);
valueY = analogRead(VRY_PIN);
// converts the analog value to commands
// reset commands
command = COMMAND_NO;
// check left/right commands
if (valueX < LEFT_THRESHOLD)
command = command | COMMAND_LEFT;
else if (valueX > RIGHT_THRESHOLD)
command = command | COMMAND_RIGHT;
// check up/down commands
if (valueY < UP_THRESHOLD)
command = command | COMMAND_UP;
else if (valueY > DOWN_THRESHOLD)
command = command | COMMAND_DOWN;
// NOTE: AT A TIME, THERE MAY BE NO COMMAND, ONE COMMAND OR TWO COMMANDS
// print command to serial and process command
if (command & COMMAND_LEFT) {
Serial.println("COMMAND LEFT");
xAngle--;
}
if (command & COMMAND_RIGHT) {
Serial.println("COMMAND RIGHT");
xAngle++;
}
if (command & COMMAND_UP) {
Serial.println("COMMAND UP");
yAngle--;
}
if (command & COMMAND_DOWN) {
Serial.println("COMMAND DOWN");
yAngle++;
}
}
if (button.isPressed()) {
Serial.println("The button is pressed");
xAngle = 90; // the center position of servo #1
yAngle = 90; // the center position of servo #2
}
xServo.write(xAngle); // rotate servo motor 1
yServo.write(yAngle); // rotate servo motor 2
// print data to Serial Monitor on Arduino IDE
Serial.print("Servo Motor's Angle: ");
Serial.print(xAngle);
Serial.print("°, ");
Serial.print(xAngle);
Serial.println("°");
}
Quick Instructions
COM6
Autoscroll
Clear output
9600 baud
Newline
Code Explanation
Read the line-by-line explanation in comment lines of source code!
Video Tutorial
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