RC using attachInterrupt

#include <SD.h>

#include "FastLED.h"

// How many leds in your strip?
#define NUM_LEDS 60

// For led chips like Neopixels, which have a data line, ground, and power, you just
// need to define DATA_PIN.  For led chipsets that are SPI based (four wires - data, clock,
// ground, and power), like the LPD8806, define both DATA_PIN and CLOCK_PIN
#define DATA_PIN 6
#define CLOCK_PIN 13
int rcPin = 2; // PWM signal arduino pin(prev code only)
int Speed = 0;    // Receiver channel 1 pwm value
// Define the array of leds
CRGB leds[NUM_LEDS];






//pin 2, INT0, is receiving PWM input
#define CHANNEL_1_PIN 2

//micros when the pin goes LOW
volatile unsigned long timer_start;

//difference between timer_start and micros() is the length of time that the pin
//was HIGH - the PWM pulse length.
volatile int pulse_time;

//this is the time that the last interrupt occurred.
//you can use this to determine if your receiver has a signal or not.
volatile int last_interrupt_time;

//calcSignal is the interrupt handler
//that will read the PW LOW length/time on pin 2
void calcSignal()
{
//record the interrupt time so that we can tell if the receiver has a signal from the transmitter
 last_interrupt_time = micros();

//if the pin has gone LOW, record the microseconds since the Arduino started up
//reading INT0 on Pin 2
 if(digitalRead(2) == LOW)
    {
        timer_start = micros();
    }
//otherwise, the pin has gone HIGH
    else
    {
        //only worry about this if the timer has actually started
        if(timer_start > 0)
        {
            //record the pulse time
            pulse_time = ((volatile int)micros() - timer_start);
            //restart the timer
            timer_start = 0;
        }
    }
}

//this is all normal arduino stuff
void setup()
{
    FastLED.addLeds<NEOPIXEL,DATA_PIN>(leds, NUM_LEDS);
//REMOVED pinMode(rcPin, INPUT);

    timer_start = 0;
//here's the interrupt, obviously
//INT0 is on Pin 2.
    attachInterrupt(0, calcSignal, CHANGE);
    Serial.begin(115200);
}

void loop()
{
  // First slide the led in one direction
for(int i = 0; i < (NUM_LEDS / 2) - 1; i++) {
// Set the i'th led to red

leds[i] = CRGB::DarkViolet ;
leds[NUM_LEDS - i -1] = CRGB::DarkViolet ;
// Show the leds
FastLED.show();

/*when PW raw time is viewed in serial monitor I get values average 20100
and 20900. below is formula to convert the numbers to a range of 0-100.
100 being low throttle and 0 for high/full throttle.
*/
pulse_time= pulse_time -20100;

if (pulse_time >800) {
   pulse_time=800;}
   pulse_time= pulse_time/8;
   if (pulse_time <0) {
   pulse_time=0;}
//print the value so I can monitor it
Serial.println(pulse_time);
//I get wildly jumping values in the monitor if I do not put this delay in
delay(25);

// now that we've shown the leds, reset the i'th led to black
leds[i] = CRGB::Black;
leds[NUM_LEDS - i -1] = CRGB::Black;
// Wait a little bit before we loop around and do it again
//delay time of 25 gives a medium slow pattern movement
//if I try to put the 'pulse_time' var in 25's place, it will not work
//and the serial monitor will lock up with only a few zero's showing
//the LED's will not move either. I think the UNO locks up :(
 delay(25);
}


// Now go in the other direction.
for(int i = (NUM_LEDS / 2); i > 0; i--) {

// Set the i'th led to red
leds[i] = CRGB::Red;
leds[NUM_LEDS - i -1] = CRGB::Red;
// Show the leds
FastLED.show();
pulse_time= pulse_time -20100;

if (pulse_time >800) {
   pulse_time=800;}
    pulse_time= pulse_time/8;
   if (pulse_time <0) {
   pulse_time=0;}
Serial.println(pulse_time);
delay(25);

// now that we've shown the leds, reset the i'th led to black
leds[i] = CRGB::Black;
leds[NUM_LEDS - i -1] = CRGB::Black;
// Wait a little bit before we loop around and do it again
 delay(25);
}

}