Since minigris did not perform as hoped, I’ve had to go back to basics and rebuild the circuit, testing at each stage. Hence a test matrix, where I build the circuit with a component added, write a test program, test on the Arduino (if necessary), then test the ATMega chip on battery power.
The rows are: LED blink, photocell confirm, dual photo cell, servo, 2 servo, and 2 photo cell plus 2 servo. As you can see from the check offs, I’m about halfway through. So far, everything has worked first time through. I expect that will change.
(At the time of the photo, the ATMega was on the Arduino waiting to be reprogrammed with the servo test program.)