Product Descriptions
Linear Hall magnetic module and number 13 comes with LED build a simple circuit to produce magnetic field warning lamp.
Use digital 13 interface comes with the LED.
The linear Hall magnetic module connected digital 3 interfaces.
When the linear Hall magnetic module senses detected the key signal. LED lights on, otherwise off.

Routines source code:
int Led = 13 ;// define LED Interface
int buttonpin = 3; // define the linear Hall magnetic sensor interface
int val ;// define numeric variables val
void setup()
{
pinMode(Led, OUTPUT) ;// define LED as output interface
pinMode(buttonpin, INPUT) ;// define linear Hall magnetic sensor as output interface
}
void loop ()
{
val = digitalRead(buttonpin) ;// digital interface will be assigned a value of 3 to read val
if(val == HIGH) // When the linear Hall magnetic sensor detects the signal, LED flashes
{
digitalWrite(Led, HIGH);
}
else
{
digitalWrite (Led, LOW);
}
}