IR remote control using the ATMega 328P/644P

[Cosec02]

I am currently trying to replicate the signals from a heat pump remote control and have been able to successfully do so using an Arduino(both sending and receiving). However, I am trying to transfer this functionality directly to an ATMega 328P but have a couple of queries,

1. If the goal is to generate a PWM signal, why is the external clock pin(XTAL) being used as the sending pin in the code for the Atmel microcontrollers. Should it not be one of the output capture pins?

2)This might be a stupid question, but would this code still function without the "Arduino.h" header file if the target device is an Atmel microcontroller? Since this is for a academic project, I am limited to using the MPLAB IDE and am not allowed to use anything Arduino related.

[ArminJo]

Ägypten?

[Cosec02]

I'm sorry?

[ArminJo]

Do you need help or do you want to present a riddle?

[Cosec02]

I love riddles as much as the next person but I'm on a bit of time crunch so help would be appreciated haha