KY-025 Analog, magnetic reed sensor

If a magnetic field is detected, this is output at the digital output.

  • Arduino
  • Raspberry Pi
  • Raspberry Pi Pico
  • Micro:Bit

This module contains an analog reed magnetic sensor that detects a magnetic field and forwards this information to the digital output. Reed contacts consist of two thin contact springs in a glass tube, which move towards each other in the presence of a magnetic field. This closes an electrical contact and the signal is switched through.

When the sensor detects a magnetic field, it closes the contact and emits a digital signal. This makes the reed magnetic sensor ideal for applications where the presence of a magnet needs to be detected, such as in door and window alarms, position sensors or other security and monitoring systems. The simple operation and reliability of the reed magnetic sensor make it a useful component for many projects where magnetic fields need to be detected.

User note

This sensor is ideally suited for threshold value measurement. This means that the sensor emits a digital high signal as soon as a threshold value set by the user on the rotary potentiometer is exceeded. It should be noted here that the digital signal is a comparison of the value set on the rotary potentiometer and the measured value on the sensor, which are then compared by the LM393 comparator installed on the board. The set value of the rotary potentiometer is the threshold value, which is used to define a logical high signal.

Digital output: If a magnetic field is detected, a signal is output here

Analog output: Direct measured value of the sensor unit

LED1: Indicates that the sensor is supplied with voltage

LED2: Indicates that a magnetic field has been detected

Functionality of the sensor

This sensor has two functional components on its circuit board: The front sensor unit, which physically measures the environment and outputs it as an analog signal to the second unit, the comparator. The comparator compares the measured value of the sensor with the value set on the rotary potentiometer and outputs a logical high signal on the digital pin and LED L1 if the value on the rotary potentiometer is exceeded.

Please note: The signal is inverted. If a high value is measured, this results in a lower voltage value at the analog output.

The rotary potentiometer can be set as follows:

Pin assignment


Arduino Sensor
5 V +V
GND GND
Pin 3 Digital Signal
Pin A0 Analog Signal

Code example

The program reads the current voltage value, which can be measured at the analog output, and outputs it via the serial interface. In addition, the state of the digital pin is also indicated in the console. This indicates whether the limit value has been exceeded.

To load the following code example onto your Arduino, we recommend using the Arduino IDE. In the IDE, you can select the appropriate port and board for your device.

Copy the code below into your IDE. To upload the code to your Arduino, simply click on the upload button.

// Declaration and initialization of the input pins
int analog_input = A0; // Analog output of the sensor
int digital_input = 3; // Digital output of the sensor
  
void setup () {
  pinMode(analog_input, INPUT);
  pinMode(digital_input, INPUT);
  Serial.begin(9600); // Serial output with 9600 bps
  Serial.println("KY-025 Magnetic field detection");
}
  
// The program reads the current values of the input pins
// and prints them to the serial output
void loop () {
  float analog_value;
  int digital_value;
    
  // Current values are read out, converted to the voltage value...
  analog_value = analogRead(analog_input) * (5.0 / 1023.0); 
  digital_value = digitalRead(digital_input);
    
  //... and printed at this point
  Serial.print("Analog voltage value: "); 
  Serial.print(analog_value, 4);
  Serial.print(" V, \t Threshold value: ");
  
  if (digital_value == 1) {
      Serial.println("reached");
  }
  else {
      Serial.println("not yet reached");
  }
  Serial.println("----------------------------------------------------------------");
  delay(1000);
}

This module contains an analog reed magnetic sensor that detects a magnetic field and forwards this information to the digital output. Reed contacts consist of two thin contact springs in a glass tube, which move towards each other in the presence of a magnetic field. This closes an electrical contact and the signal is switched through.

When the sensor detects a magnetic field, it closes the contact and emits a digital signal. This makes the reed magnetic sensor ideal for applications where the presence of a magnet needs to be detected, such as in door and window alarms, position sensors or other security and monitoring systems. The simple operation and reliability of the reed magnetic sensor make it a useful component for many projects where magnetic fields need to be detected.

User note

This sensor is ideally suited for threshold value measurement. This means that the sensor emits a digital high signal as soon as a threshold value set by the user on the rotary potentiometer is exceeded. It should be noted here that the digital signal is a comparison of the value set on the rotary potentiometer and the measured value on the sensor, which are then compared by the LM393 comparator installed on the board. The set value of the rotary potentiometer is the threshold value, which is used to define a logical high signal.

Digital output: If a magnetic field is detected, a signal is output here

Analog output: Direct measured value of the sensor unit

LED1: Indicates that the sensor is supplied with voltage

LED2: Indicates that a magnetic field has been detected

Functionality of the sensor

This sensor has two functional components on its circuit board: The front sensor unit, which physically measures the environment and outputs it as an analog signal to the second unit, the comparator. The comparator compares the measured value of the sensor with the value set on the rotary potentiometer and outputs a logical high signal on the digital pin and LED L1 if the value on the rotary potentiometer is exceeded.

Please note: The signal is inverted. If a high value is measured, this results in a lower voltage value at the analog output.

The rotary potentiometer can be set as follows:

Pin assignment


Raspberry Pi Sensor
GPIO 24 [Pin 18] Digital Signal
3,3 V [Pin 1] +V
GND [Pin 6] GND
- Analog Signal
Sensor KY-053
Analog Signal A0
Digital Signal -
+V -
GND -
Raspberry Pi KY-053
GPIO 3 [Pin 5] SCL
GPIO 2 [Pin 3] SDA
3,3 V [Pin 17] +V
GND [Pin 14] GND

Analog sensor, therefore the following must be considered: The Raspberry Pi has, in contrast to the Arduino, no analog inputs or there is no ADC (analog digital converter) integrated in the chip of the Raspberry Pi. This limits the Raspberry Pi, if you want to use sensors, which do not output digital values, but a continuously changing value (example: potentiometer -> different position = different voltage value).

To avoid this problem, our sensor kit X40 contains the KY-053, a module with a 16-bit ADC, which you can use on the Raspberry to expand it with 4 analog inputs. This module is connected to the Raspberry Pi via I2C, takes over the analog measurement and transfers the value digitally to the Raspberry Pi.

So we recommend to connect the KY-053 module with the mentioned ADC in between for analog sensors of this set. You can find more information on the KY-053 Analog Digital Converter information page.

Code example

Attention! To use this module in combination with the KY-053 Analog-Digital-Converter, a virtual environment must be set up. All the necessary information can be found here.

#!/usr/bin/python
# coding=utf-8
import time
import board
import busio
import adafruit_ads1x15.ads1115 as ADS
from adafruit_ads1x15.analog_in import AnalogIn
import gpiozero

# Create the I2C bus
i2c = busio.I2C(board.SCL, board.SDA)

# Create the ADC object using the I2C bus
ads = ADS.ADS1115(i2c)

# Create single-ended input on channels
chan0 = AnalogIn(ads, ADS.P0)
chan1 = AnalogIn(ads, ADS.P1)
chan2 = AnalogIn(ads, ADS.P2)
chan3 = AnalogIn(ads, ADS.P3)

delayTime = 1
Digital_PIN = 24

input = gpiozero.DigitalInputDevice(Digital_PIN, pull_up=None, active_state=True)

while True:
    analog = '%.2f' % chan0.voltage
 
    # Output to the console
    if input.is_active == False:
        print ("Analog voltage value:", analog,"V, ","Limit value: not yet reached")
    else:
        print ("Analog voltage value:", analog, "V, ", "Limit value: reached")
        print ("---------------------------------------")
 
    time.sleep(delayTime)

This module contains an analog reed magnetic sensor that detects a magnetic field and forwards this information to the digital output. Reed contacts consist of two thin contact springs in a glass tube, which move towards each other in the presence of a magnetic field. This closes an electrical contact and the signal is switched through.

When the sensor detects a magnetic field, it closes the contact and emits a digital signal. This makes the reed magnetic sensor ideal for applications where the presence of a magnet needs to be detected, such as in door and window alarms, position sensors or other security and monitoring systems. The simple operation and reliability of the reed magnetic sensor make it a useful component for many projects where magnetic fields need to be detected.

User note

This sensor is ideally suited for threshold value measurement. This means that the sensor emits a digital high signal as soon as a threshold value set by the user on the rotary potentiometer is exceeded. It should be noted here that the digital signal is a comparison of the value set on the rotary potentiometer and the measured value on the sensor, which are then compared by the LM393 comparator installed on the board. The set value of the rotary potentiometer is the threshold value, which is used to define a logical high signal.

Digital output: If a magnetic field is detected, a signal is output here

Analog output: Direct measured value of the sensor unit

LED1: Indicates that the sensor is supplied with voltage

LED2: Indicates that a magnetic field has been detected

Functionality of the sensor

This sensor has two functional components on its circuit board: The front sensor unit, which physically measures the environment and outputs it as an analog signal to the second unit, the comparator. The comparator compares the measured value of the sensor with the value set on the rotary potentiometer and outputs a logical high signal on the digital pin and LED L1 if the value on the rotary potentiometer is exceeded.

Please note: The signal is inverted. If a high value is measured, this results in a lower voltage value at the analog output.

The rotary potentiometer can be set as follows:

Pin assignment


Micro:Bit Sensor
Pin 1 Digital Signal
3,3 V +V
GND GND
- Analog Signal
Sensor KY-053
Analog Signal A0
Digital Signal -
+V -
GND -
Micro:Bit KY-053
Pin 19 SCL
Pin 20 SDA
3,3 V VDD
GND GND

Analog sensor, therefore the following must be observed: The Micro:Bit has analog inputs or there is an ADC (analog digital converter) integrated in the chip of the Micro:Bit. However, these are only limited to 10-bit and therefore offer only a rather low accuracy for analog measurements.

To avoid this problem, our sensor kit X40 contains the KY-053, a module with a 16-bit ADC, which you can use on the Micro:Bit to expand it by 4 analog inputs. This is connected to the Micro:Bit via I2C, takes over the analog measurement and transfers the value digitally to the Micro:Bit.

Therefore we recommend to connect the KY-053 module with the mentioned ADC in between for analog sensors of this set. More information can be found on the KY-053 Analog Digital Converter information page KY-053 Analog Digital Converter.

Code example

The program uses the corresponding library from us to control the ADS1115 ADC. This has been published under the following link pxt-ads1115 under the MIT-License.

	
		pins.setPull(DigitalPin.P1, PinPullMode.PullUp)
		ADS1115.setMode(mode.Multi)
		ADS1115.setRate(rate.Rate5)
		ADS1115.setGain(gain.One)
		ADS1115.initADS1115(userInI2C.Gnd)
		basic.forever(function () {
		    serial.writeString("Analog Value: ")
		    serial.writeLine("" + (ADS1115.raw_to_v(ADS1115.read(0))))
		    if (pins.digitalReadPin(DigitalPin.P1) == 1) {
		        serial.writeLine("Magnetic field detected!")
		    } else {
		        serial.writeLine("No magnetic field detected")
		    }
		    serial.writeLine("_____________________________________")
		    basic.pause(1000)
		})

Sample program download

microbit-KY-025

This module contains an analog reed magnetic sensor that detects a magnetic field and forwards this information to the digital output. Reed contacts consist of two thin contact springs in a glass tube, which move towards each other in the presence of a magnetic field. This closes an electrical contact and the signal is switched through.

When the sensor detects a magnetic field, it closes the contact and emits a digital signal. This makes the reed magnetic sensor ideal for applications where the presence of a magnet needs to be detected, such as in door and window alarms, position sensors or other security and monitoring systems. The simple operation and reliability of the reed magnetic sensor make it a useful component for many projects where magnetic fields need to be detected.

User note

This sensor is ideally suited for threshold value measurement. This means that the sensor emits a digital high signal as soon as a threshold value set by the user on the rotary potentiometer is exceeded. It should be noted here that the digital signal is a comparison of the value set on the rotary potentiometer and the measured value on the sensor, which are then compared by the LM393 comparator installed on the board. The set value of the rotary potentiometer is the threshold value, which is used to define a logical high signal.

Digital output: If a magnetic field is detected, a signal is output here

Analog output: Direct measured value of the sensor unit

LED1: Indicates that the sensor is supplied with voltage

LED2: Indicates that a magnetic field has been detected

Functionality of the sensor

This sensor has two functional components on its circuit board: The front sensor unit, which physically measures the environment and outputs it as an analog signal to the second unit, the comparator. The comparator compares the measured value of the sensor with the value set on the rotary potentiometer and outputs a logical high signal on the digital pin and LED L1 if the value on the rotary potentiometer is exceeded.

Please note: The signal is inverted. If a high value is measured, this results in a lower voltage value at the analog output.

The rotary potentiometer can be set as follows:

Pin assignment


Raspberry Pi Pico Sensor
GPIO26 (A0) Analog Signal
GND GND
3 V +V
GPIO18 Digital Signal

You can also use an ADC such as the KY-053. This ADC has a higher resolution than the internal ADC of the Raspberry Pi Pico, which means that the sensor can be analysed more accurately.

Code example

The program reads the current voltage value, which can be calculated by reading the analog output, and outputs it on the serial interface. In addition, the state of the digital pin is also indicated in the console. This indicates whether the limit value has been exceeded.

To load the following code example onto your Pico, we recommend using the Thonny IDE. All you have to do first is go to Run > Configure interpreter ... > Interpreter > Which kind of interpreter should Thonny use for running your code? and select MicroPython (Raspberry Pi Pico).

Now copy the code below into your IDE and click on Run.

# Load libraries
from machine import Pin, ADC
from time import sleep

# Initialization of ADC0
adc = ADC(0)
# Initialization of GPIO18 as input
digital = Pin(18,Pin.IN, Pin.PULL_UP)

print("KY-025 Magnetic field detection")

# Endless loop for reading out the ADC
while True:
    raw_value = adc.read_u16()
    # Conversion from analog value to voltage
    Volt = round(raw_value* 3.3 / 65536, 2)
    digital_value = digital.value()

    # Serial output of the analog value and the calculated voltage
    print("Analog voltage value: " + str(Volt) + " V\t Threshold value: ", end="")

    # Query whether the digital value has changed with serial output
    if digital_value == 1:
        print("reached")
    else:
        print("not reached")
    
    print("----------------------------------------")
    sleep(2)