Display contrast, as most of the tutorials explain. Very important.
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And do not connect the contrast potentiometer to 5 V. That is a very old mistake parroted by sloppy constructors. 
If using a 10k potentiometer (actually the wrong value but) connect both ends to ground and the wiper to pin 3.
I need to sit down and think about this one. Thank you!
What O/S version is on the Mac? I read here that there are problems with Big Sur. There are workarounds I believe.
Yes, remove the red wire to the potentiometer. Connect that potentiometer pin to black as well as the other!
This makes it into a 5 k variable resistor which is closer to the 1k variable resistor that should connect between pin 3 and ground with no connection to 5 V.
This will make the contrast setting easier - and FWIW, also saves half a milliamp.
So, looks like I am getting correct wiring diagram after all!!! Thank you for your help!!!
Maybe someone did this before. I am getting little bit confused here. I understand that Uno will get its own power as 5V USB or 9 V adapter. Which way is preferable?
My actuator is 12 V. So actuator control board will get 12 V from external adapter. Communication to Uno will be done only on one wire and second wire is ground. Red wire will be cut and ignored? I will post some pictures for clarification.
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