I did some search online. Everything I saw was using existing FTDI232 breakout board to build stuff. This gives me the impression that the chip, when properly connected to USB and arduino, will need no programming and just works on a board.
I found this in its spec sheet:
Entire USB protocol handled on the chip. No USB specific firmware programming required.
I’m designing a project and decided to go from ATMEGA32U4 (after learning building bootloader) to ATMEGA328P-AU. I just need the FTDI chip like an old arduino would need it. I suppose a couple of decoupling caps and a cap between its DTR and ATMEGA328P-AU RESET will do. Am I too naive?
Sparkfun’s PCB tutorial has it: