SENSORS/ACTUATORS

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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

We will explore the code for both use cases in the next parts.

Hardware Used In This Tutorial

1	×	ESP-WROOM-32 Dev Module
1	×	Micro USB Cable
1	×	Joystick
2	×	Servo Motor
2	×	(Optional) Pan-tilt kit with servo motor
1	×	Jumper Wires
1	×	(Optional) 5V Power Adapter
1	×	(Optional) DC Power Jack
1	×	(Optional) ESP32 Screw Terminal Adapter

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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

ESP32 Code

ESP32 Code - The servo motors rotate according to the movement of the joystick's thump

Quick Instructions

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.
On Arduino IDE, Navigate to Tools Manage Libraries

Type ESP32Servo on the search box, then look for the keypad library by Mark Stanley, Alexander Brevig
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

COM6

Send

Coming soon

Autoscroll Show timestamp

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 GIOP36 (ADC0) connected to VRX pin #define VRY_PIN 39 // ESP32 pin GIOP39 (ADC0) connected to VRY pin #define SW_PIN 17 // ESP32 pin GIOP17 connected to SW pin #define SERVO_X_PIN 33 // ESP32 pin GIOP33 connected to Servo motor 1 #define SERVO_Y_PIN 26 // ESP32 pin GIOP26 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

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

COM6

Send

Autoscroll Show timestamp

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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Function References

Learn More

ESP32 - Joystick

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