I want to build a controller from scratch (not just painting an existing one) and was wondering if it's possible to brick my console of I messed something up. Does anyone know specifically what I should be careful of?
Side note can I use any 4021 shift register, there seems to be a lot of different codes , as far as I know they're all the same in function but any knowledge on this would also help. The one I'm looking at is CD4021BCN. Thanks.
Yes, if you shorted some wires or otherwise sent too much current through the controller port you could damage it. (Example: I've heard pressing start on a Genesis controller plugged into a C64 does horrible things to it.)
I don't think every possible version of 4021 ICs are valid, but if it's made for 5V operation then it should be fine.
There's only one "generation" of 4000 series ICs, unlike 7400 series ICs. 4000 series ICs are always CMOS, are always comparatively slow, are always capable of operating on 3 to 15V.
The NES controller port is not the best engineered for safety.
1- As always, be careful about not shorting +5V to ground. Inside the NES (right? not famicom?) mainboard, there's no overcurrent protection at all. This is actually less dangerous than:
2- Several of the pins connect straight to the NES's CPU, without any more protection beyond over- and under- voltage protection diodes. Shorting "OUT" or "CLK" to any other pin could kill your NES.