Feature request: DB9 joystick input via GPIOs

[sajattack]

There are so many GPIOs on DE10 Nano, surely we can spare 9 (or less) for low-latency retro joystick input?

[sorgelig]

There are no confirmed input lags. USB input lag for joysticks is usually 2-5ms while retro consoles query the joysticks once per frame, i.e. once per 16-20ms.
Input lag is commercial myth.

P.S.: DB9 Atari style joystick have 2 buttons max which is not enough for MiSTer.

[sajattack]

Ok, maybe lag was the wrong way to frame the problem, wouldn't it still be good to support classic joysticks?

[hmusta]

Some retro consoles (such as the NES) may poll joysticks more than once per frame:
https://wiki.nesdev.com/w/index.php/Controller_reading_code#DPCM_Safety_using_Repeated_Reads

[sorgelig]

There are many USB converters for classic joysticks. So they are basically supported already.

[sorgelig]

Some retro consoles (such as the NES) may poll joysticks more than once per frame:
https://wiki.nesdev.com/w/index.php/Controller_reading_code#DPCM_Safety_using_Repeated_Reads

MiSTer has no such glitch as original joystick. And this trick is basically just to get the same - get the joystick data once per frame. Core can query the joystick data as fast as it wants - it won't make it slower or other issues.