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.

Model:COM11335P

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
  

Specification

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

Usage

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 - Basic Shield and the LED is connected to digital port 13. When there is Magnetic approaches the switch, the SIG pin output a High voltage. Then the LED light. 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, Please click here if you do not know how to upload.
  
• Then the LED light when there is Magnetic approaches the switch. Have a try!

Version Tracker

Revision	Descriptions	Release
Grove - Magnetic Switch v1.0	Initial public release designed for Grove module	Jan 12, 2011

Resources

• Grove-Magnetic Switch Eagle File
• CT10 datasheet

Support

If you have questions or other better design ideas, you can go to our forum or wish to discuss.