XBox RF thingy ? v1.0

/*
  Reddit edit - 3 November 2019

  This is an edit of some code posted online that appeared to have an error in it.

  The source of the code is here: https://dilisilib.wordpress.com/hacking/xbox-360-rf-module-arduino/

*/

/* Arduino code to communicate with xbox 360 RF module.
  Original work by (yaywoop) / additional ideas from Alexander Martinez - modified by dilandou (www.dilandou.com, www.diru.org/wordpress)
  First sends LED initialisation code followed by LED startup animation code, then sleeps until a button press for sync command.
  RF module must be powered with 3.3V, two diodes in series with USB 5v will do. Connect the USB wires to a host computer, and the data and serial wires to Arduino.
  of course, make sure to have a common ground */

#include <avr/sleep.h>

#define sync_pin 2 //power button repurposed for sync button (pin 5 on the module)
#define data_pin 3 //data line (pin 6 on the module)
#define clock_pin 4 //clock line (pin 7 on module)

int led_cmd[10] =  {0, 0, 1, 0, 0, 0, 0, 1, 0, 0}; //Activates/initialises the LEDs, leaving the center LED lit.
int anim_cmd[10] = {0, 0, 1, 0, 0, 0, 0, 1, 0, 1}; //Makes the startup animation on the ring of light.
int sync_cmd[10] = {0, 0, 0, 0, 0, 0, 0, 1, 0, 0}; //Initiates the sync process.
volatile boolean sync_enable = 0;

void sendData(int cmd_do[]) {
  pinMode(data_pin, OUTPUT);
  digitalWrite(data_pin, LOW);    //start sending data.
  int prev = 1;
  for (int i = 0; i < 10; i++) {
    /*
        while (prev == digitalRead(clock_pin)) {} //detects change in clock <--------------------------------------- What is this supposed to do???
        prev = digitalRead(clock_pin);
        // should be after downward edge of clock, so send bit of data now
        digitalWrite(data_pin, cmd_do[i]);

        while (prev == digitalRead(clock_pin)) {} //detects upward edge of clock <--------------------------------------- What is this supposed to do???
          prev = digitalRead(clock_pin);
        }
        digitalWrite(data_pin, HIGH);
        pinMode(data_pin, INPUT);
    */

    // Below is what I am guessing this was supposed to do.
    // I don't have an xbox to test with however...

    while (prev != digitalRead(clock_pin)) { //detects change in clock
      prev = digitalRead(clock_pin);
      // should be after downward edge of clock, so send bit of data now
      digitalWrite(data_pin, cmd_do[i]);
    }
    while (prev == digitalRead(clock_pin)) { //detects upward edge of clock
      prev = digitalRead(clock_pin);
      digitalWrite(data_pin, HIGH);
      // pinMode(data_pin, INPUT); <------------------- and this is probably wrong here also.
    }
  }
  pinMode(data_pin, INPUT); // <----------------------- looks better here, outside of the loop to send data...?
}

void initLEDs() {
  sendData(led_cmd);
  delay(50);
  sendData(anim_cmd);
  delay(50);
}

void wakeUp() {
  sync_enable = 1;
}

void sleepNow() {
  set_sleep_mode(SLEEP_MODE_PWR_DOWN); // set sleep mode
  sleep_enable(); //enable sleep bit
  attachInterrupt(0, wakeUp, LOW);
  sleep_mode();
  sleep_disable(); //disable sleep bit
  detachInterrupt(0); // disables interrupt 0 on pin 2
}

void setup() {
  Serial.begin(9600);
  pinMode(sync_pin, INPUT);
  digitalWrite(sync_pin, HIGH);
  pinMode(data_pin, INPUT);
  pinMode(clock_pin, INPUT);
  delay(2000);

  initLEDs();
  //  sendData(sync_cmd);
}

void loop() {
  Serial.println("Sleeping.");
  sleepNow();
  delay(200);
  if (sync_enable == 1) {
    Serial.println("Syncing.");
    sendData(sync_cmd);
    sync_enable = 0;
  }
}