FastLed (WS2812B) and IRRemote problem I am trying to control my WS2812B with a remote control. To archive this, I am using IRRemote library. The problem is that this two libraries doesn't work together.

I did some research and found out that it is a problem with timers.But, inside the IRRemote library file (boarddefs.h) there is a possibility to choose different timer (It uses TIMER2 as default, so I supposed that FastLed uses also Timer2). 

So when I change the timer in boarddefs.h file to TIMER1, it is also now working fine for me. I keep recieving random IR codes. When I stop using FastLed library, I recive correct codes.

Some workaround to this problem is to read IR signal only once irrecv is idle:

  while (!irrecv.isIdle());  // if not idle, wait till complete
  if (irrecv.decode(&amp;results)) {
     ...
  }


It makes around 80% of readings correct. 

I am using arduino NANO clone. My question is, if there is any way to use IRRemote and FastLed libraries together other than using two arduino NANO (use one to read IR and other to control LEDs)?
The WS2812B chips are highly timing-dependent. You have to clock out bits within a range of ±150 ns. This isn't likely to work well with clocking in bits from an IR remote. You are finding errors on the IR codes - that doesn't surprise me.

I suggest you use your idea of two Nanos. One can be reading IR codes. The other can display a stream of pixels and then "ask" the other one (eg. via serial or I2C) if a different command has arrived. That way the timing can be shifted in such a way that both processors are not interrupted when they are busy.