Control circuit design review
I'm starting work on my Car PC in a 2012 Honda CR-Z, and I've run into an issue that I thought would be common, but lots of searching hasn't found anything useful. The background here is that I want to have my reverse camera work even if the computer is off. So if I pull the PC out to work on it, or it breaks down, I'll still have rear visible. However, if the computer is up and running, I want the camera to be displaying through the PC so I can put an overlay on it and I want to have the camera powered at all times when the PC is running so I can record the video in case I am in an accident or something.
Here is the logic:
LCD Power is ON when the M4-ATX has power OR if I am in reverse
LCD is showing Reverse camera (directly) if the PC is not yet ready AND I am in reverse
Reverse camera has power if the PC is ready OR I am in reverse
The blocks with 'NO' are Normally-Open relays, 'NC' is a Normally-Closed relay, and 'NO-10S' is a 10-second Delay-On, Normally-Open relay. I've omitted diodes, LEDs, and ground connections in the diagram. Input is on the left, Output on the right, and Control is either top or bottom.
My crappy way of sensing the PC being ready is to use a time-delayed relay - eventually that will be replaced with a USB controlled NO-relay that is set/released on Windows startup/shutdown.
Anyone have criticisms or recommendations? I'm not an electrical engineer, I'm a software engineer, so if it sucks don't be shy. :)