connect more input to micro from pc817

Arduino Sketch

#include <TimerOne.h>
volatile int i = 0;                               // Variable to use as a counter
volatile boolean zero_cross = 0;   // Boolean to store a "switch" to tell us if we have crossed zero
int AC_pin = 3;                                               // Output to Opto Triac
int dim = 128;                                              // Dimming level (0-128)  0 = on, 128 = 0ff
int freqStep = 77;                                    // This is the delay-per-brightness step in microseconds.
int a = 0;
int pin = 13;
int data = 0;
void setup() 
{
Serial.begin(9600);
pinMode(AC_pin, OUTPUT);                              // Set the Triac pin as output
attachInterrupt(0, zero_cross_detect, RISING);    // Attach an Interupt to Pin 2 (interupt 0) for Zero Cross Detection

Timer1.initialize(freqStep);                                   // Initialize TimerOne library for the freq we need

Timer1.attachInterrupt(dim_check2, freqStep);

}

void zero_cross_detect()

{

zero_cross = true;               // set the boolean to true to tell our dimming function that a zero cross has occured

i = 0;

digitalWrite(AC_pin, LOW);

}

// Turn on the TRIAC at the appropriate time

void dim_check2()

{

if (zero_cross == true) {

if (i >= dim) {

digitalWrite(AC_pin, HIGH);    // turn on light

i = 0;                                                        // reset time step counter

zero_cross = false;                                // reset zero cross detection

}

else {

i++;                                                 // increment time step counter

}

}

}

void loop() {

if (Serial.available()) {
a++;
if (a == 1) data = Serial.read();
if (a == 2) 
 {
pin = Serial.read();
a = 0;
dim = data;
}
}
}