@stan2004 posted:'interchangeable use of terms signal ground, track ground, earth ground, outer-rail ground, trigger ground, chassis ground, logic ground, local ground, ground coffee'
LOL ... you forgot 'hallowed ground and ground down to a bloody pulp.
'Especially in this case where you're driving an unknown environment.' 'OK, I think I made my point. LOL.'
Succinctly, with great clarity and relevance!
'I was assuming a generic DC opto-coupler which has an "open-collector" transistor as its output pins and thereby would only turn on when the Arduino outputs the short reset pulse.'
I'm assuming that's why I didn't see any triode tubes
. My experience to date with the 'pre-fab' optocouplers is the output duplicates the input. If it receives a high (1) it outputs a high (1), if it receives a low (0) it outputs a low (0). But I can easily test that. Tri-State in Arduino speak would be : pinMode((pin x), INPUT_PULLUP). I will say previously I've only set the pin's pinMode during setup, but I see no reason (yet) that it couldn't be toggled (from Input to Output do a digitalWrite and back to Input) during a subroutine. Again, an easy test (easy to say as I sit here not having tried that yet).
Just did a little research and according to :
https://www.baldengineer.com/w...pinmode-and-why.html 'Starting with IDE 1.0.1, if pinMode() is called with INPUT, the internal pull-up resistor is explicitly disabled. However, when pinMode() is called with INPUT_PULLUP, the pull-up will be enabled. You can still override the state of the pin after pinMode() has been called by using digitalWrite.'That sounds like I may not have to change the pinMode, simply do a digitalWrite. But, I'm never that lucky.
'frying the DCS-RC custom-programmed microcontroller chip which is surely irreplaceable.' ' in my opinion of course!
'
Which is spot on and always valued! Thanks, Barry
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