KY-021 Mini reed magnet

int Led = 13 ;// declaration of the LED output pin
int Sensor = 10 ;// Declaration of the sensor input pin
int val; // Temporary variable
   
void setup ()
{
  pinMode (Led, OUTPUT) ; // Initialize output pin
  pinMode (Sensor, INPUT) ; // Initialize sensor pin
}
   
void loop ()
{
  val = digitalRead (Sensor) ; // The current signal at the sensor is read out
   
  if (val == HIGH) // If a signal could be detected, the LED is switched on.
  {
    digitalWrite (Led, LOW);
  }
  else
  {
    digitalWrite (Led, HIGH);
  }
}

If a magnetic field is detected, the two input pins are short-circuited by pulling them towards each other.

Technical dara

Operating voltage	3,3 V - 5 V
Dimensions	19 x 18,5 x 9 mm

Pin assignment

Code example Raspberry Pi

Pin assignment Raspberry Pi

Raspberry Pi	Sensor
GPIO 24 [Pin 18]	Signal
3.3 V [Pin 1]	+V
GND [Pin 6]	GND

This is an example program where a console output is generated as soon as a signal is detected.

# Required modules are imported and set up
import RPi.GPIO as GPIO
import time
   
GPIO.setmode(GPIO.BCM)
   
# Here the input pin is declared, to which the sensor is connected. Additionally the PullUP resistor at the input will be activated
GPIO_PIN = 24
GPIO.setup(GPIO_PIN, GPIO.IN)
   
print("Sensor test [press CTRL+C to end test]")
   
# This outputFunction will be executed on signal detection
def outputFunction(null):
        print("Signal detected")
   
# When a signal is detected (falling signal edge) the output function is executed
GPIO.add_event_detect(GPIO_PIN, GPIO.FALLING, callback=outputFunction, bouncetime=100) 
   
# main program loop
try:
    while True:
        time.sleep(1)
   
# clean up after the program is finished
except KeyboardInterrupt:
    GPIO.cleanup()

Sample program download

KY021-RPi.zip

To start with the command:

sudo python3 KY021-RPi.py

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

# Initialization of GPIO as input
sensor = Pin(26, Pin.IN, Pin.PULL_DOWN)

# Continuous loop for continuous serial output
while True:
    if sensor.value() == 0:
        print("Magnetic field")
    else:
        print("No magnetic field")

    print("------------------------------------------------------")
    sleep(0.5)