Gina

Mine have a common -ve rail - a solid strip of copper from input to output. I only connect one end to avoid any earth loops.

Been searching out the input impedance of the Arduino Analog inputs and it seems to be 100MΩ in parallel with 14pF so that's fine. For extra protection I could include Schottky barrier diodes to prevent current being fed into the RPi as I have proposed for the RPi inputs. I have several BAT43 diodes - 30v 200mA. Though with the logic 1 level being 3v, any ordinary signal diode would do.

New diagram.

Forgot the rain detector too!! Hope I'm not losing it - I seem to be getting very forgetful! With the Arduino Nano being powered through the Vcc terminal rather than Vin there is slightly less danger of a fault causing destruction of the RPi and I'm wondering if I need all those optocouplers. If I were to feed the RPi output lines into the Arduino Analog inputs there is little chance of +5v being fed back to the RPi to kill it. Inputs to RPi could be fed through a resistive divider or maybe a Schottky diode pulling the input to Gnd and blocking any positive input current. This would simplify the RPi to Arduino interconnections considerably. Another point I've thought of is the remote Abort signal. There could be a conflict between the Rain Detected signal and the remote Abort. I was thinking an Abort is necessary for safety but an Abort signal could be caused by a fault and prevent roof closure when rain is detected - we don't want that. I think rain detection should take priority and Abort only recognised following a manual opening or closing.

I'm wondering though if I need to know the motor current remotely. As long as it's roughly normal, I don't think I do. The only dodgy condition is if the roof is jammed and the motor is taking excess current. The Arduino sketch can take care of this but a fault condition would need reporting remotely. At least this would mean only one information line about the motor current - Normal or Fault.

Just realised that I've forgotten a couple of inputs I need on the RPi to feed back to the indoor control system - limit switch states. Need to know for sure that the roof is closed properly or fully open. Doesn't need extra Arduino lines though - it can be commoned up with the limit switch inputs to the Arduino. Does need 2 more optocouplers and two more GPIO lines on the RPi.

Oh no it isn't!! The optocoupler LEDs are upside down, a couple of wire junctions are wrongly placed and ...

I think this is just about the finished block diagram.

Gradually improving the diagram.

Roof control block diagram.

I've got dia working better now.

If you show your true colours, so will I 😁

And the frustrations just seem to go on and on...

Yes indeed, but I've actually had white hair for some time now.

Probably time to change my Avatar to show the white hair I have now...

Gonna watch Countdown...

dia does not seem to be suitable for what I want. Maybe I'd be better drawing the diagram on paper and photographing it (or scanning it). I really don't want to spend several days finding a suitable diagram drawing app!

Seem to have a problem. Just adding 3 boxes for RPi, Arduino Nano and Motor Driver. Found all sorts of symbols I can add so that's good but trying to add text labels I can't seem to enlarge the text. "Properties" doesn't work.

Installed dia with Symaptic - looks interesting and useful. More suitable than LO Draw.

Back to the rain detector. Rain started with fine drizzle and nothing detected in 10 minutes, got heavier and was then detected.

It was LibreOffice Draw I used. Here's an example.

Ditto...

Don't think I know that one.

Trying to recall which software I used for drawing circuit and block diagrams. Thought it was LibreOffice Draw but can't seem to get it to do what I want.