I have a fully functioning software suite now for my garage door opener. I have been using a small simulator program on the Raspberry Pi to pull the pins up and down (using the pullup and pulldown resistors). Tonight I plugged in one of the actual rotary encoders, and it works fine. And now that I think about it, I don’t really need the optocouplers on the inputs, since I’m using encoders with NPN open collector outputs. All I need to do is enable the pull-up resistors. This is also true for the garage door closed switches. Hence I am going to draw up a second board with a lot fewer components. The component cost wasn’t significant for the board I have now, but it’ll save on my effort to populate the board. By dropping the optocouplers, I will eliminate 15 components. And technically I could probably eliminate the filtering capacitors too since the encoder cable is shielded. That would eliminate 4 more components.
I hate the amount of board space required for the relays, but I need them. I considered using MOSFETs or Darlingtons, but I decided it was just a bad idea to tie the Raspberry Pi ground to my garage door opener’s ground pin. It’d be a recipe for ground loop disasters. The relays keep the Raspberry Pi isolated. I am using relay drivers to drive the relays, which just saves on component count and board space.
I have a decent web interface now, which runs on my web server and communicates with the Raspberry Pi (encrypted). I have yet to implement the separate up/down logic, but since the web interface shows the movement of the door, it’s not strictly necessary. Door activation works, and I can see whether the door is opening or closing.
My code on the Raspberry Pi will learn the door travel from a full open/close cycle, so the graphic in the web interface is very representative of the amount the door is open.