I haven't tested all of the electronics, but I have been thinking about some of the things that I want to have this do. It's got to be complicated enough to keep up my own selfish interest, but it's got to be straightforward enough that someone else in my household does not poison me because of it.

• At full power, these things are pretty bright. I want to have a dimmer control (PWMs).
• The dimmer will be combined with an ON/OFF switch so that the previously-set dimmer level is remembered. I'm not completely sure about this, and I might change it to having a comfortable default dimmer level when the lights are turned on.
• Because of multiple garage entrances, I want to have switches in multiple locations (at least 2, maybe 3) that can do the same things that the main switchbox can do.
• Each switch should have an LED or something so it's easy to find in the dark. This is called a pilot light, I think. (I probably won't use natural gas :-). )
• The place where people work on things is not necessarily close to the switches, so I want to be able to place the motion sensors (PIRs) in other places. I'm thinking of ceiling mount, but I'm not sure if I will need 1 or 2 sensors.
• The lights coming on or going off should be fades of some short duration.
• When the lights are going to turn off (because of the timer and no motion detected), it should give some kind of warning. For example, maybe 30 seconds before turning off, the lights gently blink. This is so someone quietly doing something is not suddenly plunged into darkness.
• I haven't figured out yet if I want the timer to be some fixed duration or if I want to be able to adjust that with some kind of control. Based on how I observe others using adjustable timers, they just pick the max time anyhow. So maybe I'll skip the complexity.
• There will be a 12V DC power supply for the LED strips. With a simple power supply module, I can step that down to drive my microprocessor at 5V. Because I am not sure what the future might bring, I may provide a jumper option to have the voltage out to the load be either the same as the input voltage or be the same as the stepped down voltage. I'm really not sure if it's worth it or if I just want a reason to have a jumper.
• I plan to use rotary encoders for the dimmer control. There is probably some cut-off for the PWM where the LEDs don't work stably or have too much flicker or whatever. And, obviously, there is a max PWM duty cycle of 100%. I want some kind of feedback to the human that they have reached one of those points. Maybe I'll blink the pilot light for feedback.

That's all for now. I'll revise this list later as my thinking evolves.