Grove - Magnetic Switch

Introduction

This is a Grove interface compatible Magnetic switch module. It is based on encapsulated dry reed switch CT10. CT10 is single-pole, single throw (SPST) type, having normally open ruthenium contacts. The sensor is a double-ended type and may be actuated with an electromagnet, a permanent magnet or a combination of both. The magnetic switch is a wonderful tool for designers who would like to turn a circuit on and off based on proximity.

Features

• Grove compatible interface
• 2.0cm x 2.0cm Grove module
• Minimum external parts
• 10W rating
• Rugged encapsulation

Application Ideas

• Proximity Sensor
• Security Alarm Sensor
• Level Sensor
• Flow Sensor
• Pulse Counter

Specifications

Items	Min	Norm	Max	Unit
Working Voltage	4.75	5.0	5.25	V
Switched Power	10			W
Switched Voltage AC,RMS value(max)	< 140			V
Switched Current DC	< 500			mA
Carry Current DC	< 0.5			A
Contact Resistance	<200			mΩ
Insulation Resistance	>106			MΩ
Operating Temperature	-40	-	125	℃
Operate Range	10	-	40	AT

Platforms Supported

Usage

With Arduino

The SIG pin of the module output LOW normally. When a magnet approaches the switch, the magnetic switch close and the SIG pin output HIGH.

The following sketch demonstrates a simple application of using the Magnetic switch to control the led. When you put a magnet that has enough magnetic power close to the module, the switch is closed .Then the SIG pin out put a high voltage. You can use this to control the led.

As the picture on the below indicates, the Magnetic switch is connected to digital port 9 of the Grove - Base Shield and the LED is connected to digital port 13. When a Magnet approaches the switch, the SIG pin outputs a High voltage. Then the LED lights up. The hardware installation is as follows:

• Copy and paste code below to a new Arduino sketch.

    /*******************************************************************************/

    /*macro definitions of magnetic pin and LED pin*/
    #define MAGNECTIC_SWITCH 9
    #define LED 13//the on board LED of the Arduino or Seeeduino

    void setup()
    {
        pinsInit();
    }

    void loop() 
    {
        if(isNearMagnet())//if the magnetic switch is near the magnet?
        {
            turnOnLED();
        }
        else
        {
            turnOffLED();
        }
    }
    void pinsInit()
    {
        pinMode(MAGNECTIC_SWITCH, INPUT);
        pinMode(LED,OUTPUT);
    }

    /*If the magnetic switch is near the magnet, it will return ture, */
    /*otherwise it will return false                                */
    boolean isNearMagnet()
    {
        int sensorValue = digitalRead(MAGNECTIC_SWITCH);
        if(sensorValue == HIGH)//if the sensor value is HIGH?
        {
            return true;//yes,return ture
        }
        else
        {
            return false;//no,return false
        }
    }
    void turnOnLED()
    {
        digitalWrite(LED,HIGH);
    }
    void turnOffLED()
    {
        digitalWrite(LED,LOW);
    }

• Upload the code.
• Then the LED light when there is Magnetic approaches the switch. Have a try!

With Raspberry Pi

1.You should have a raspberry pi and a grovepi or grovepi+.

2.You should have completed configuring the development enviroment, otherwise follow here.

3.Connection

• Plug the Magnet Switch to grovepi socket D3 by using a grove cable.

4.Navigate to the demos’ directory:

    cd yourpath/GrovePi/Software/Python/

• To see the code (this demo has the same usage with tilt switch)

    nano grovepi_tilt_switch.py   # "Ctrl+x" to exit #

    import time
    import grovepi

    # Connect the Grove Tilt Switch to digital port D3
    # SIG,NC,VCC,GND
    tilt_switch = 3

    grovepi.pinMode(tilt_switch,"INPUT")

    while True:
        try:
            print grovepi.digitalRead(tilt_switch)
            time.sleep(.5)

        except IOError:
            print "Error"

5.Run the demo.

    sudo python grove_tilt_switch.py

6.Result

Put a magnet upon the sensor, the SIG pin will output HIGH.

Resources

• Grove-Magnetic Switch v0.9 Eagle File
• CT10 Datasheet
• Grove-Magnetic Switch v1.3 Eagle File
• Grove-Magnetic Switch v1.3 PDF File

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