Quick question here:
Input button is located a few hundred feet from microcontroller.
5V will most likely not work.
If I would let's say send 24vDC through the line and have a voltage divider at the return Arduino input (ex R1=2.4mOhm, R2=610kOhm), would this help with signal integrity/reduce voltage drop?
Sure it will. But unless the connections are shielded, electrical noise picked up from the environment may be a serious problem. Long leads are antennas.
Would a cat5 cable with all leads except connected to ground except for one (input) work? Can't get better than that, correct?
Twisted pairs, shielding
That should work. The grounds should all be connected but only at the Arduino end. For additional noise resistance, use a low value pullup resistor (e.g. 4.7K).
Cat5 DC loop resistance is supposed to be < 0.19 Ohms/m.
Why not on both ends? Issue with the switch pcb having a ground plane?
Also will connecting arduino ground to earth ground make things better or worse? Are we looking to ground to system ground or everything to earth ground?
That is a general rule, to avoid potentially even more destructive ground loops.
https://www.mouser.com/pdfdocs/alphawire-Understanding-Shielded-Cable.pdf
See Practical Guideline #5.
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Wow. Never knew that. So why are things like XLR cables (audio), Cat5 ethernet, etc, grounded end to end?
Those are intended to be used only in environments where ground loop problems are not anticipated. In industrial environments ground loops can be a very serious problem.
Note that Ethernet connections are magnetically isolated.
But there is usually no reason to ground both ends. The outer shield should protect the inner conductors quite well when grounded at only one end.
Thanks!
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