Cute little discovery along the way...

So I started work on the startup diagnostic script for MARCO, but when I went to turn the lights on, nothing happened.  Not to be deterred, I ripped out my relay board and tested the simple lighting circuit on a breadboard.
What I found is that when the mosfet is placed between the light assembly and the 11V source, nothing happens, but when it is placed between the light and ground, the circuit works as intended.

This happens because the load voltage increases when voltage on the gate increases, raising voltage on the source and consequently lowering Vgs which keeps the transistor conducting. This of course doesn't happen when the source is grounded.

Hopefully by the end of the week I'll have a rebuilt relay board and gpio-operated peripherals so I can begin LIDAR and camera software integration.

5-hour-later edit:  The LED circuits are all wired up and functional, however I am having difficulty with the filter actuator.  Since the actuator is just a big hunky electromagnet, it really needs all the current it can suck out of the battery, and it just isn't getting that from the mosfets with 3.3V on the gates.  

If you care about numbers: the actuator punches along happily at ~1.2 A, and the lowest I've gotten it to click is at about 800 mA.  The mosfets were allowing less than 200 mA through.

For now, I ordered a handful of Darlington Pairs which I'm going to drive to saturation to see if I can blast more current through those actuator solenoids, but in the meantime I will continue developing the start-up diagnostics and then move on to camera & LIDAR integration.

MARCO can work without the actuator, but that would mean I wasted a colossal amount of time building the thing basically from garbage I found in the street and under my bed, so I'm not ready to give up on it quite yet.

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