I have a project where the operation f on
is to be controlled from a remote (20m plus) location.
I’ve got 4x4 and 3x4 keypads, and can interface them with my controller, which will likely be a Nano.
I’m concerned that the distance could make this an unreliable connection.
Suggestions please ….
TIA
Set up the receiver and try it! Be aware of obstacles like walls etc. They are the real enemies.
It will be hard-wired….
I could go wireless, using pair of Wemos D1 minis, but this has to be 100% bombproof, I can’t guarantee the keypad station will have power !!
Using 4 - 20 mA current loop is one possibility.
Please make a drawing what You aim for and be precise about the demands. This way no solution will be created.
give details of the keypads? e.g. links
A bit of lateral thinking leads me to believe I only need at most 3 buttons, possibly less, so could be as simple as hard-wiring direct to inputs… The keypad idea just came about because I have them,
I would, of course, use screened cable to minimise any pickup, and stronger pull-up resistors on the inputs ..
Actually going positive-logic inputs might be better, buttons pressed giving a “high” input.
please give more information on such a keypad! Sounds like switches on the end of wires.
Yes, 4x4 matrix keypads, but I’ve decided against using them now…
No. Use negative going-logic and strong pull up near the input reading the signal.
Well that would be simpler, as I don’t need to supply power to the remote buttons.
What would you suggest as a “strong pullup” resistance on each input ? I’m thinking about 10K ?
For a long run like that, the strong pull-up should let the switch draw about 2 mA.
You can try. It depends on the cables You use and the electrical noise around. 470 or 1K are thinkable.
