Hyundai Aftermarket.org: Arduino EF Meter - Hyundai Aftermarket.org

 /*
   Copyright 2010 Adam N. Outler     Licensed under the Apache License, Version 2.0 (the "License");    you may not use this file except in compliance with the License.    You may obtain a copy of the License at         http://www.apache.org/licenses/LICENSE-2.0     Unless required by applicable law or agreed to in writing, software    distributed under the License is distributed on an "AS IS" BASIS,    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.    See the License for the specific language governing permissions and    limitations under the License. */

//A note on HZ, if you notice meter oscillations on a known steady 
//  signal increase or decrease hertz by 1.  The oscillations are
//  caused when the signals are in near-perfect resonance. 
float FrequencyToMonitor=59; //hertz


//setup pins
#define ANTENNA 31 //antenna pin
//16 LEDs on 16 different pins
int LEDPin[]={ 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52 } ;
int LEDCount=16;    //number of LEDs

//setup initial global values
int LEDCounter=0; 		//initial value of LEDs to display
int HalfPeriodMicroseconds=0;// initial value of halfwavelength

/*
   SETUP defines pins and performs POT(Power On Test) on LEDs
*/
void setup()  { 
   double HalfPeriod=((1/FrequencyToMonitor)*.5);   //Half-period in seconds from frequency
   HalfPeriodMicroseconds=int(1000000*HalfPeriod);  //Convert period seconds to microseconds integer

   pinMode(ANTENNA, INPUT);               	//set antenna pin
   for (int Pin=0; Pin < LEDCount; Pin++)  { //initialize each LED 
    pinMode(LEDPin[Pin], OUTPUT);          
    digitalWrite(LEDPin[Pin], HIGH);          //Turn the LED on
    delay(50);
    digitalWrite(LEDPin[Pin], LOW);          //Turn the LED back off
   }
   swingLEDs();   	//perform LED check to verify LED functionality
} 


/*
   LOOP checks for value of antenna to go high and then low
   if change is seen, then 2 LEDs are lit, otherwise total number
   of LEDS are decreased.  This allows for a magentic effect when
   near the field.
*/
void loop(){
   int ANTENNAValue=0;    //sets and resets ANTENNAValue
   int OldANTENNAValue=0; // as well as OldANTENNAValue


   for ( int Pass=0; Pass < 4; Pass++ )  {//take 4 readings
    ANTENNAValue=digitalRead(ANTENNA);    //   from the antenna
    if ( ( ANTENNAValue == HIGH ) && ( OldANTENNAValue == LOW ) ) {
   	incrementLED(); //If a change is detected increase twice
   	incrementLED(); //   4 passes means 3 changes total
    } else if ( ( ANTENNAValue ==  LOW ) && ( OldANTENNAValue == HIGH ) ) {
   	incrementLED(); //   This makes the meter rise by
   	incrementLED(); //   a total factor of  2 and
    } else {
   	decrementLED(); //   if there is no change it falls by 1
    }
   	OldANTENNAValue=ANTENNAValue; //Log old value for next pass
   	delayMicroseconds(HalfPeriodMicroseconds);  // half-wave pause before next reading
   }
   delayMicroseconds(HalfPeriodMicroseconds); //visual delay between reading passes
   delayMicroseconds(HalfPeriodMicroseconds); //twice to avoid extremely long numbers   
}


/*
FUNCTION swingLEDs tests the LEDs by lighting
them up sequentially.  Each LED is brought high
then low twice. 
*/
void swingLEDs(){
 	for (int Pin=0; Pin < LEDCount; Pin++)  {
 	digitalWrite(LEDPin[Pin], HIGH);  // instantanious full brightness
   }
   for (int Pin=0; Pin < LEDCount; Pin++)  {
 	digitalWrite(LEDPin[Pin], LOW);   // clear LEDs from left to right
 	delay(20);
   }
   for (int Pin=LEDCount; Pin > -1; Pin--)  {
 	digitalWrite(LEDPin[Pin], HIGH);  // light LEDs from right to left
 	delay(20);
   }
   for (int Pin=LEDCount; Pin > -1; Pin--)  {
 	digitalWrite(LEDPin[Pin], LOW);   // clear LEDs from right to left
 	delay(20);
   }
}

/* 
FUNCTION incrementLED increases the number
of LEDs lit by 1.  
*/
void incrementLED(){
    if ( LEDCounter <  LEDCount  - 1  ){ LEDCounter++;} //if not max increase
    digitalWrite(LEDPin[LEDCounter], HIGH); //light new LED
}

/*
FUNCTION decrementLED decreases the number
of LEDs lit by 1.
*/
void decrementLED(){
   digitalWrite(LEDPin[LEDCounter], LOW); //turn off current LED
   if ( LEDCounter >= 0 ){ LEDCounter-- ;} // if not zero, decrease}