How to Use Rotary Encoder Knob with Push Button: Examples, Pinouts, and Specs

A rotary encoder knob is a type of input device that allows for precise control of parameters by rotating the knob. It is commonly used in applications where incremental adjustments are required, such as volume control, menu navigation, or parameter tuning. This component typically includes a push button feature that can be pressed to select or confirm actions, making it versatile for user interfaces in various electronic devices.

• Audio equipment for volume or tone control
• User interfaces for menu navigation
• Robotics for precise motor control
• Industrial equipment for parameter adjustments
• DIY electronics projects

Below are the key technical details for a standard rotary encoder knob with a push button:

The rotary encoder typically has 5 pins. Below is the pinout and description:

1. Connect the Power Supply:

   • Connect the VCC pin to a 3.3V or 5V power source.
   • Connect the GND pin to the ground of your circuit.

2. Connect the Signal Pins:

   • Connect the CLK and DT pins to digital input pins on your microcontroller.
   • Use pull-up resistors if the encoder does not have them built-in.

3. Connect the Push Button:

   • Connect the SW pin to a digital input pin on your microcontroller.
   • Add a pull-up resistor if necessary.

4. Debounce the Signals:

   • Use hardware (capacitors) or software (code) to debounce the rotary encoder and push button signals.

5. Read the Signals:

   • Monitor the CLK and DT pins to determine the direction of rotation.
   • Monitor the SW pin to detect button presses.

Below is an example code snippet for using a rotary encoder knob with a push button on an Arduino UNO:

// Rotary Encoder Pins
#define CLK 2  // Connect to the CLK pin of the encoder
#define DT 3   // Connect to the DT pin of the encoder
#define SW 4   // Connect to the SW pin of the encoder

int counter = 0;          // Variable to store the encoder count
int currentStateCLK;      // Current state of the CLK pin
int lastStateCLK;         // Previous state of the CLK pin
bool buttonPressed = false; // Flag for button press detection

void setup() {
  pinMode(CLK, INPUT);
  pinMode(DT, INPUT);
  pinMode(SW, INPUT_PULLUP); // Use internal pull-up resistor for the button

  // Read the initial state of the CLK pin
  lastStateCLK = digitalRead(CLK);

  Serial.begin(9600); // Initialize serial communication
}

void loop() {
  // Read the current state of the CLK pin
  currentStateCLK = digitalRead(CLK);

  // Check if the state of CLK has changed
  if (currentStateCLK != lastStateCLK) {
    // Determine the direction of rotation
    if (digitalRead(DT) != currentStateCLK) {
      counter++; // Clockwise rotation
    } else {
      counter--; // Counterclockwise rotation
    }

    // Print the counter value to the Serial Monitor
    Serial.print("Counter: ");
    Serial.println(counter);
  }

  // Update the last state of CLK
  lastStateCLK = currentStateCLK;

  // Check if the button is pressed
  if (digitalRead(SW) == LOW) {
    if (!buttonPressed) {
      Serial.println("Button Pressed!");
      buttonPressed = true; // Set the flag to avoid multiple detections
    }
  } else {
    buttonPressed = false; // Reset the flag when the button is released
  }
}

• Debouncing: Rotary encoders and push buttons often produce noisy signals. Use software or hardware debouncing to ensure reliable readings.
• Pull-up Resistors: Ensure pull-up resistors are used for the SW pin if not already built into the encoder.
• Power Supply: Verify the operating voltage of your encoder to avoid damage.
• Signal Monitoring: Use interrupts for more accurate and responsive signal detection, especially in time-sensitive applications.

1. Unstable or Erratic Readings:

   • Cause: Signal noise or lack of debouncing.
   • Solution: Implement software debouncing or add capacitors for hardware debouncing.

2. Push Button Not Responding:

   • Cause: Missing pull-up resistor or incorrect wiring.
   • Solution: Check the wiring and ensure a pull-up resistor is used.

3. No Signal from CLK or DT Pins:

   • Cause: Incorrect connections or damaged encoder.
   • Solution: Verify the connections and test the encoder with a multimeter.

4. Incorrect Direction Detection:

   • Cause: Swapped CLK and DT connections.
   • Solution: Swap the CLK and DT connections and test again.

Q: Can I use this encoder with a 3.3V microcontroller?
A: Yes, most rotary encoders are compatible with both 3.3V and 5V systems. Verify the specifications of your specific model.

Q: How do I increase the resolution of the encoder?
A: The resolution is determined by the encoder's design. To achieve finer control, consider using an encoder with more steps per revolution.

Q: Can I use multiple encoders in the same circuit?
A: Yes, you can use multiple encoders by connecting each to separate input pins on your microcontroller.

Q: Do I need external components for this encoder?
A: You may need pull-up resistors and capacitors for debouncing, depending on your encoder model and circuit design.