My guru told me long ago that I’d find myself cutting traces on printed circuit boards to problem solve. I thought I must have been lucky to go two-for-two without any hardware problems, but I found that the FTDI problem with my valve board was electronic, not software. I neglected to include a 100 nF capacitor between the FTDI DTR header and the ATMega328p reset line. I probably should have checked my FTDI header on the breadboard, but I must have instead assumed it behaved similar to the ICSP header reset connection, which connects directly to the reset pin. Anyway, I’ve finally cut my first trace to solder in the capacitor. Here it is successfully running the blink sketch, this time loaded via USB rather than AVR programmer.
Considering that I’m redesigning the valve with a geared-up DC motor, the ICSP header wasn’t appropriately sized to allow a proper header, and I’d like to reorient the radio breakout board to not hang off the edge, I’ll probably have a new set of boards fabricated.
Another day. I’m again on call tomorrow.