Electronics > Beginners
Debugging a breadboard computer: spurious signals, noise, and voltage weirdness?
PfhorSlayer:
Thank you everyone for the great advice and tips! There's a lot to take in here, so I'm going to spend some time going over everything and doing my best to ensure that what I've got available to me right now (breadboards, and lots of wire!) are as solid as possible. After everything works, I'm planning on expanding it and moving it to proper PCBs (as they're SO DAMN CHEAP now!). Despite the fact that solder-less breadboards have a number of inherent issues, I think by debugging the problems with things laid out like this, where the kinds of issues I'll run into tend to be more pronounced and obvious, will help me learn how to design my PCBs to avoid many such issues, even if they would be far less significant there.
Ben Eater's videos and kits are fantastic, but it does seem a little too convenient that he was able to make the entire computer work the way he laid it out, with unused gate inputs left floating, absolutely zero decoupling caps across ICs, and everything else hooked up more in line with theory, and less with reality. In fact, I'd wager that every single person who's put together his kits has happened across very similar issues to what I'm facing! It's a great way to be forced to learn about how things work, but it would have been nice to be aware of the potential issues up front, rather than having to dig around asking for help later on.
Either way, I'm still learning, and I'm closer to completing the first revision of the board now! Thank you all again for the incredibly helpful information you've all provided!
PfhorSlayer:
As a small update, with the power issues resolved (proper decoupling caps, more lines coming in from the wall-supply to the board, etc.), the computer successfully ran a program to compute the Fibonacci sequence up to 233 (the largest value in the sequence that fits in 8 bits)! Everything works!
bd139:
Nice work!
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