How to Use Modulo Mini Interruptor Magnetico: Examples, Pinouts, and Specs

The Modulo Mini Interruptor Magnetico (KY21), manufactured by Keys, is a compact magnetic switch module designed to detect the presence of a magnetic field. This module is widely used in security systems, such as door and window sensors, to detect when a door or window is opened or closed. It is also suitable for other applications requiring magnetic field detection, such as proximity sensing and automation systems.

• Security systems (e.g., door/window sensors)
• Proximity detection in industrial automation
• Magnetic field detection in DIY electronics projects
• Smart home systems for monitoring doors and windows

The following table outlines the key technical details of the KY21 module:

The KY21 module has three pins, as described in the table below:

1. Power the Module: Connect the VCC pin to a 3.3V or 5V power source and the GND pin to the ground of your circuit.
2. Connect the Output: Connect the OUT pin to a digital input pin of your microcontroller or to another circuit that requires the magnetic field detection signal.
3. Place the Magnet: Position a magnet near the module. When the magnet is within the detection range, the OUT pin will go LOW. When the magnet is removed, the OUT pin will return to HIGH.

• Magnet Strength: Ensure the magnet used is strong enough to be detected within the desired range.
• Placement: Avoid placing the module near strong electromagnetic interference (EMI) sources, as this may affect its performance.
• Debouncing: If using the module with a microcontroller, consider implementing software debouncing to handle any noise or fluctuations in the output signal.

Below is an example of how to connect and use the KY21 module with an Arduino UNO:

• Connect the VCC pin of the KY21 to the 5V pin of the Arduino.
• Connect the GND pin of the KY21 to the GND pin of the Arduino.
• Connect the OUT pin of the KY21 to digital pin 2 of the Arduino.

// KY21 Magnetic Switch Module Example
// This code reads the output of the KY21 module and prints the status to the Serial Monitor.

const int sensorPin = 2; // KY21 OUT pin connected to digital pin 2
int sensorState = 0;     // Variable to store the sensor state

void setup() {
  pinMode(sensorPin, INPUT); // Set the sensor pin as input
  Serial.begin(9600);        // Initialize serial communication at 9600 baud
}

void loop() {
  sensorState = digitalRead(sensorPin); // Read the state of the sensor

  if (sensorState == LOW) {
    // Magnet is detected
    Serial.println("Magnet detected!");
  } else {
    // Magnet is not detected
    Serial.println("No magnet detected.");
  }

  delay(500); // Wait for 500ms before reading again
}

1. The module does not detect the magnet:

   • Solution: Ensure the magnet is within the detection range (10mm to 20mm). Use a stronger magnet if necessary.
   • Solution: Verify that the module is powered correctly (3.3V to 5V) and that all connections are secure.

2. The output signal is unstable:

   • Solution: Check for sources of electromagnetic interference (EMI) near the module and relocate it if needed.
   • Solution: Add a capacitor (e.g., 0.1µF) across the power supply pins to filter noise.

3. The module outputs a constant HIGH signal:

   • Solution: Ensure the magnet is not too far from the module. Test with a different magnet if needed.
   • Solution: Verify that the OUT pin is properly connected to the microcontroller or circuit.

Q: Can the KY21 module detect any type of magnet?
A: Yes, the KY21 can detect most types of magnets, but the detection range depends on the magnet's strength and size.

Q: Can I use the KY21 with a 3.3V microcontroller?
A: Yes, the KY21 operates within a voltage range of 3.3V to 5V, making it compatible with 3.3V microcontrollers like the ESP32.

Q: Is the KY21 suitable for outdoor use?
A: The KY21 is not waterproof or weatherproof. If used outdoors, it should be enclosed in a protective casing to prevent damage from moisture or dust.