Arduino Project

Arduino Servo Angle Control with Rotary Encoder

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Name	Includes Arduino board	PURCHASE LINK
Elite Explorer Kit	Arduino Uno R4 WiFi	BUY
3 in 1 Ultimate Starter Kit	Arduino Uno R4 Minima	BUY

Course Introduction

This Arduino project uses a rotary encoder to precisely control a servo motor, allowing you to set its angle from 0° to 180° in adjustable steps.

An OLED display provides real-time feedback, showing the current servo angle and step size, while a button on the encoder lets you switch between fine and coarse adjustments.

This interactive setup demonstrates digital input for accurate motor positioning and live data display.

Note

If this is your first time working with an Arduino project, we recommend downloading and reviewing the basic materials first.

1.1 Install Arduino IDE(Important)
1.2 Introduction of Arduino IDE

Required Components

In this project, we need the following components:

SN	COMPONENT INTRODUCTION	QUANTITY	PURCHASE LINK
1	Arduino UNO R4 WIFI	1	BUY
2	USB Type-C cable	1	×
3	Breadboard	1	BUY
4	Wires	Several	BUY
5	Digital Servo Motor	1	BUY
6	Rotary Encoder Module	1	BUY
7	OLED Display Module	1	BUY

Wiring

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Common Connections:

Digital Servo Motor
Connect to breadboard’s positive power bus.
Connect to breadboard’s negative power bus.
Connect to 4 on the Arduino.

Rotary Encoder Module
SW: Connect to 9 on the Arduino.
DT: Connect to 10 on the Arduino.
CLK: Connect to 11 on the Arduino.
GND: Connect to breadboard’s negative power bus.
VCC: Connect to breadboard’s red power bus.

OLED Display Module
SDA: Connect to A4 on the Arduino.
SCK: Connect to A5 on the Arduino.
GND: Connect to breadboard’s negative power bus.
VCC: Connect to breadboard’s red power bus.

Writing the Code

Note
You can copy this code into Arduino IDE.
To install the library, use the Arduino Library Manager and search for Adafruit SSD1306 and Adafruit GFX and install it.
Don’t forget to select the board(Arduino UNO R4 Minima/WIFI) and the correct port before clicking the Upload button.

#include <Servo.h>           // Include servo motor control library
#include <Wire.h>            // Include I2C communication library
#include <Adafruit_GFX.h>    // Include core graphics library
#include <Adafruit_SSD1306.h>// Include SSD1306 OLED display library

// OLED display parameters
#define SCREEN_WIDTH 128     // OLED display width in pixels
#define SCREEN_HEIGHT 64     // OLED display height in pixels
#define OLED_RESET    -1     // No hardware reset pin used
#define SCREEN_ADDR   0x3C   // I2C address for OLED display
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

// Rotary encoder pins
#define ENCODER_CLK  11      // Encoder output A (CLK)
#define ENCODER_DT   10      // Encoder output B (DT)
#define ENCODER_SW    9      // Encoder button switch (SW)

// Servo control pin
#define SERVO_PIN     3      // Servo signal pin

Servo myServo;              // Create servo object
int angle = 90;             // Initial servo angle (0-180)
int stepSize = 1;           // Rotation step: 1°, 5°, or 10°
int lastClkState;           // Previous state of CLK for edge detection
int lastSwState;            // Previous state of SW for debounce
unsigned long lastDebounce = 0;
const unsigned long DEBOUNCE_MS = 50; // Debounce time in milliseconds

void setup() {
  // Initialize encoder pins with internal pull-ups
  pinMode(ENCODER_CLK, INPUT_PULLUP);
  pinMode(ENCODER_DT,  INPUT_PULLUP);
  pinMode(ENCODER_SW,  INPUT_PULLUP);

  Serial.begin(9600);      // Start serial communication for debugging

  myServo.attach(SERVO_PIN); // Attach servo to control pin
  myServo.write(angle);    // Move servo to starting angle

  // Initialize OLED display and halt if failed
  if (!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDR)) {
    Serial.println("SSD1306 allocation failed");
    while (true);          // Stop execution on failure
  }
  display.clearDisplay();  // Clear the buffer
  display.display();       // Display cleared buffer

  // Read initial encoder states
  lastClkState = digitalRead(ENCODER_CLK);
  lastSwState  = digitalRead(ENCODER_SW);

  updateDisplay();         // Draw the initial UI
}

void loop() {
  // Detect rotation on rising edge of CLK
  int clkState = digitalRead(ENCODER_CLK);
  if (clkState != lastClkState && clkState == HIGH) {
    // Determine direction using DT
    if (digitalRead(ENCODER_DT) != clkState) angle = max(0, angle - stepSize);
    else                                   angle = min(180, angle + stepSize);
    myServo.write(angle);  // Move servo to new angle
    updateDisplay();       // Update the display
  }
  lastClkState = clkState;

  // Detect button press with debounce
  int swState = digitalRead(ENCODER_SW);
  if (swState != lastSwState) {
    unsigned long now = millis();
    if (now - lastDebounce > DEBOUNCE_MS && swState == LOW) {
      // Cycle step sizes: 1 -> 5 -> 10
      if      (stepSize == 1)  stepSize = 5;
      else if (stepSize == 5)  stepSize = 10;
      else                      stepSize = 1;
      updateDisplay();        // Refresh display after change
    }
    lastDebounce = now;
  }
  lastSwState = swState;
}

// Draw UI elements on OLED display
void updateDisplay() {
  // Energy bar region (0-20px)
  display.fillRect(0, 0, SCREEN_WIDTH, 20, BLACK);
  display.drawRect(0, 0, SCREEN_WIDTH, 20, WHITE);
  int barWidth = map(angle, 0, 180, 0, SCREEN_WIDTH);
  if (barWidth > 2) display.fillRect(1, 1, barWidth - 2, 18, WHITE);

  // Tick marks and labels (20-32px)
  display.fillRect(0, 20, SCREEN_WIDTH, 12, BLACK);
  display.setTextSize(1);
  display.setTextColor(WHITE);
  int ticks[] = {0, 30, 60, 90, 120, 150, 180};
  for (int deg : ticks) {
    int x = map(deg, 0, 180, 0, SCREEN_WIDTH);
    display.drawLine(x, 20, x, 24, WHITE);
    char buf[4]; snprintf(buf, sizeof(buf), "%d", deg);
    int16_t tbx, tby; uint16_t tbw, tbh;
    display.getTextBounds(buf, 0, 0, &tbx, &tby, &tbw, &tbh);
    display.setCursor(x - tbw/2, 25);
    display.print(buf);
  }

  // Info region (32-64px)
  display.fillRect(0, 32, SCREEN_WIDTH, 32, BLACK);
  int baseY = 34;

  // Draw "Angle" label
  display.setTextSize(1);
  const char* lblA = "Angle";
  int16_t ax, ay; uint16_t aw, ah;
  display.getTextBounds(lblA, 0, 0, &ax, &ay, &aw, &ah);
  display.setCursor(32 - aw/2, baseY);
  display.print(lblA);

  // Draw numeric angle value
  char valA[4]; snprintf(valA, sizeof(valA), "%d", angle);
  display.setTextSize(2);
  int16_t vx, vy; uint16_t vw, vh;
  display.getTextBounds(valA, 0, 0, &vx, &vy, &vw, &vh);
  int valX = 32 - vw/2;
  int valY = baseY + ah + 4;
  display.setCursor(valX, valY);
  display.print(valA);
  // Hollow degree symbol next to angle
  int r = max(1, vh / 6);
  display.drawCircle(valX + vw + r + 1,
                    valY + vh/2 - r,
                    r, WHITE);

  // Draw "Step" label
  display.setTextSize(1);
  const char* lblS = "Step";
  int16_t sx, sy; uint16_t sw_, sh;
  display.getTextBounds(lblS, 0, 0, &sx, &sy, &sw_, &sh);
  display.setCursor(96 - sw_/2, baseY);
  display.print(lblS);

  // Draw numeric step value
  char valS[4]; snprintf(valS, sizeof(valS), "%d", stepSize);
  display.setTextSize(2);
  display.getTextBounds(valS, 0, 0, &sx, &sy, &sw_, &sh);
  int sX = 96 - sw_/2;
  display.setCursor(sX, valY);
  display.print(valS);
  // Hollow degree symbol next to step
  int r2 = max(1, sh / 6);
  display.drawCircle(sX + sw_ + r2 + 1,
                    valY + sh/2 - r2,
                    r2, WHITE);

  display.display();  // Send buffer to screen
}

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Arduino Project

Arduino Servo Angle Control with Rotary Encoder

Kit purchase

Course Introduction

Required Components

Wiring

Common Connections:

Writing the Code

Arduino Project

Arduino Servo Angle Control with Rotary Encoder

Kit purchase

Course Introduction

Required Components

Wiring

Common Connections:

Writing the Code

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