Hello,
I'm wiring up a Nes-on-a-chip system to be eventually worked into a portable console. I extracted the guts of the controller and wired tact switches to the traces where the buttons go. They all work except Up, Left, and Right. There doesn't seem to be an internal pullup on these buttons - their signal pins read only ~0.3 volts when the system is on, while the functional buttons all read closer to 4. I tried an external pullup to get the signal high and that didn't work. The only times these buttons have worked (since I ripped the controller IC out) have been when I accidentally soldered directly to the trace while the system was on. Very weird. I think something's wrong inside the IC. Has anyone else run into a problem like this?
My other option is to get some 4021s shift registers and build my own controller board. Anyone done this?
Graham
I'm wiring up a Nes-on-a-chip system to be eventually worked into a portable console. I extracted the guts of the controller and wired tact switches to the traces where the buttons go. They all work except Up, Left, and Right. There doesn't seem to be an internal pullup on these buttons - their signal pins read only ~0.3 volts when the system is on, while the functional buttons all read closer to 4. I tried an external pullup to get the signal high and that didn't work. The only times these buttons have worked (since I ripped the controller IC out) have been when I accidentally soldered directly to the trace while the system was on. Very weird. I think something's wrong inside the IC. Has anyone else run into a problem like this?
My other option is to get some 4021s shift registers and build my own controller board. Anyone done this?
Graham