Egret's Navigation Light Controller

Gary built a Navigation Light Controller that has the following functions:

1. Provide an interface to the user for control, display, and alarms.
2. Provide an automatic mode that chooses masthead tricolor if the engine is off, or deck level navigation lights and steaming light when the engine is running.
3. Provide manual selection of anchor light, deck level navigation lights and steaming light, deck level navigation lights only, or masthead tricolor.
4. Turn on instrument lights whenever any navigation lights are on.
   
5. Provide manual control of the masthead emergency strobe and the foredeck worklight.
6. Continuously monitor the current being drawn by those lights that are on.  Sound an alarm if that current falls below a minimum value. i.e. indicate burnt-out bulbs or failed connections.
7. Pass a small current through the circuits of those lights that are off.  Sound an alarm if that current does not flow, indicating a fault in the circuit.
8. Display the status of the exterior lights on an interior mimic panel.
9. In automatic or anchor mode, turn off navigation or anchor lights when dawn arrives.
10. Provide engine and daylight status to an attached computer.
11. Accept commands from an attached computer.
    

These functions are accomplished by the use of a small microprocessor (a PIC 12C509, labeled 9/19 in the picture below). Input and output to the processor is via a set of shift register chips.

There is a set of  manual switches inside the DC panel that parallel the controller and can be connected in place of the controller as a backup.  There is also a substitute controller board that excludes the microprocessor and implements only basic control of the navigation lights.