In this Arduino sketch we’ll read values from both digital and analog interfaces on the KY-025, you’ll need a magnet to interact with the module.

The digital interface will send a HIGH signal when a magnetic field is detected, turning on the LED on the Arduino (pin 13)

Description

The Reed Switch Module provides a logic output when a magnetic field comes near or is removed.

PACKAGE INCLUDES:

• Reed Switch Module

KEY FEATURES OF REED SWITCH MODULE:

• Outputs logic HIGH or LOW depending on if magnetic field is near
• 3.3 and 5V compatible

This is a SPST Reed Switch module.  Reed switches are mechanical switches which are a activated by a magnet when the magnetic field pulls the switch contacts together.  Real world uses include applications such as home security where a reed switch is placed in proximity to a magnet when a window is closed.  If the window is opened, the magnet moves away from the switch that causes it to change states which can then be detected by an MCU.

The module has a SPST reed switch with NO (Normally Open) contacts until a magnet comes into close proximity to the glass envelope and then the switch contacts are closed.

The D0 output is normally LOW and will transition to HIGH when a magnet comes near.  The A0 output is normally HIGH and will transition to LOW when a magnet comes near.

There are 2 LEDs on-board.  A red LED lights when power is applied.  A second red or green LED lights when the reed switch is activated.

Module Connections

There is a 4-pin header on the assembly for making connections.  The ‘A0’ pin is a misnomer in this application as it is a digital output that is the inverse of the ‘D0’ pin.

1 x 4 Header 

• A0 = Digital output active LOW. connects to digital input on MCU
• GND / G  = Ground
• ‘+’ = 5V
• D0 = Digital output active HIGH. Connects to digital input on MCU