Code toggling a Relay with the help of Hall Effect IC and Arduino.

Arduino_Hall_Effect_IC_Relay_Toggle.ino

const int relayPin = 10;
const int hallPin = 2;

int hallVal = 0;
int relayToggle = LOW;
int previousState = HIGH; 

void setup ()
{
  pinMode (relayPin, OUTPUT);
  pinMode (hallPin, INPUT);
}
 
void loop ()
{
  hallVal = digitalRead(hallPin);
  if (hallVal == LOW && previousState==HIGH)
  {
    relayToggle=!relayToggle;
    digitalWrite (relayPin, relayToggle);
  }
  previousState=hallVal;
}