It's taken me long enough to get to this point, but I think I'm going to finish project #1. This drawing is incomplete, as I wanted to focus on just those things for which I need to write code. So I didn't draw in external power, pullups, de-coupling, power and ground wires, the LED array (7 segment, 4 digit, driven by the MX7221), the diode patch and AC running through the SSR. The Uno is representational; I'm planning on building this on the Adafruit proto board.
The project switches AC power to an A/C unit, based on the temperature in my aquarium, measured using a DS18B20. The rest of it is mostly just fluff -- stuff to play around with and learn something. The SPCO sets operational mode for the A/C unit: manual / off / auto -- in manual mode, power is on, otherwise, it's off, or controlled by the Uno. The clock is there because auto mode will function only during certain daylight hours. The RBG LEDs will provide a gross visual reference of the temperatures returned by 2 of the DS18B20s; there will be others temp measurements for fun -- not sure yet how many. The pushbuttons will switch the display from clock (default) to temperature, and there might be more of them. SW1 and the pushbuttons will use the Analog Buttons method. The LEDs on pins A3 and A4 will light for manual / auto mode.
Anything really obvious / stupid I'm missing?
Oh, I'm going to drive both the RGB LEDs using SoftPWM, even though I do have some PWM pins, because I think it'll be easier in the code to just do all the pins the same way. (That piece will be all wrapped up in a class.)
And yes, it's kinda dumb to be finishing this up at the start of Autumn.
ETA: Yes, I'll recheck the draw on the SSR, and switch it with a transistor if necessary.