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Limit Switch

Overview​

qmc

A limit switch is an electromechanical device used to detect the presence, absence, or position of an object. It operates by physical contact: when an object moves into a predefined position, it actuates the switch, opening or closing an electrical circuit. Limit switches are widely used in industrial machinery, automation systems, and safety devices to control movement, prevent over-travel, and provide position feedback.

 

Pin Configuration​

  • S - SIGNAL
  • G - GND
  • V - VCC

Key Features​

  • Mechanical or electromechanical operation for detecting position or motion
  • Durable and reliable for repeated actuation
  • Variety of actuator types: lever, roller, plunger, whisker, etc.
  • Normally Open (NO) and Normally Closed (NC) contacts for flexible circuit design
  • Wide voltage and current handling depending on model
  • Compact and robust design suitable for industrial environments

Applications​

  • Industrial Machinery – detects the end of travel of moving parts
  • Conveyor Systems – position sensing and item detection
  • Robotics & Automation – motion control and position feedback
  • Safety Interlocks – prevents machine over-travel or unsafe operation
  • Elevators & Lifts – detects door positions and travel limits
  • CNC Machines – homing switches for axes
note

We have 2 variant's of the limit switch, one is GLYPH compatible (in terms of dimension) and the other one is generic. Please choose the variant based on the size and the direction fo the switch! otherwise both of them are electrically same.

Step 1: Hardware Required​

  1. Glyph Boards
  2. Limit Switch

Step 2: Circuit Diagram​

LIMIT_SWITCH-CIRCUIT-DIAGRAM

Step 3: Code Setup​

  1. Open Arduino IDE.
  2. Make sure to install the library
  3. Copy and paste the following code into the Arduino IDE:
#define LIMIT_SWITCH_PIN  2  // Use the GPIO pin you're connecting the limit switch to

void setup() {
  Serial.begin(115200);
  pinMode(LIMIT_SWITCH_PIN, INPUT_PULLUP);  // Enable internal pull-up resistor
}

void loop() {
  int switchState = digitalRead(LIMIT_SWITCH_PIN);

  // When pressed, switchState will be LOW (0), otherwise HIGH (1)
  if (switchState == LOW) {
    Serial.println("1");  // Pressed
  } else {
    Serial.println("0");  // Not pressed
  }

  delay(100);  // Small delay to prevent flooding the serial monitor
}

Step 4: Upload the Code​

  1. Connect the Board
  • Connect your GLYPH board to your computer
  1. Select the Board and Port

Do the following settings in your Arduino IDE,

  • Tools > Board > esp32 > Pcbcupid GLYPH C3
warning

For the Pcbcupid Glyph C3 to appear under Tools > Board > esp32, the esp32 board version installed in the Arduino IDE should be greater or equal to 3.1.0.

  • Tools > Port and select the port connected to your GLYPH.
  • Tools > USB CDC on Boot > Enabled
warning

If USB CDC on BOOT not enabled, you won't be seeing any serial data on Arduino IDE.

  1. Upload the Code

    • Click the upload button (➡️ icon) or use the shortcut CRTL + U in Arduino IDE to upload the code to the board.

Step 5: Observe the Output​

The Serial Monitor output will be a stream of 1s and 0s depending on the state of the limit switch:

  • 1 → Limit switch is pressed/activated (circuit closed, GPIO reads LOW)
  • 0 → Limit switch is not pressed (circuit open, GPIO reads HIGH)

LIMIT_SWITCH-result