Electronics > Beginners
PIC I/O port affecting adjacent I/O port - why?
rstofer:
And the OP probably thought that hooking up a PIC on a breadboard would be easy!
It turns out, nothing is easy!
dom0:
--- Quote from: rstofer on November 09, 2019, 08:55:35 pm ---And the OP probably thought that hooking up a PIC on a breadboard would be easy!
It turns out, nothing is easy!
--- End quote ---
Standard logic is considered easy to handle, but pretty much all logic you can buy makes for relatively high speed circuits. Even if you are using a 74HC flip flop toggling once per second, the flip flop itself is still rather fast. On the other hand, 3.3 / 5 V CMOS is pretty tolerant to noise as well. So people can get away with a lot of funny things and things still (usually) work, considering that your average micro runs at 8-40 MHz. Actual analogue circuits with similar bandwidths are far less forgiving.
bpb:
Thanks to all who replied here. I suspect it will be easier when I've got some fundamentals down, but I did not suspect R, C, L to be so sensitive! This is nowhere near the digital realm where things are clocked and binary.
IDEngineer:
--- Quote from: bpb on November 26, 2019, 04:24:24 pm ---I did not suspect R, C, L to be so sensitive! This is nowhere near the digital realm where things are clocked and binary.
--- End quote ---
The faster the digital signal, the more it must be treated like analog. Fast rise/fall edges have amazing harmonic content, and we ignore it at our peril.
T3sl4co1l:
Worth noting, digital is a subset of analog. Analog is continuous voltages and currents, impedances and waves. Digital is a special case, where we make certain assumptions about levels and timing, and we can use simpler rules (combinatorial and sequential logic, with propagation delays).
When those assumptions get broken, we have to take a step back and look at the analog levels again. :)
Tim
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