Jiggy-Ninja:
#if defined(ARDUINO_AVR_UNO)
// Uno pin assignments
#elif defined(ARDUINO_AVR_PRO)
// Pro Mini assignments
#else
#error Unsupported board selection.
#endif
BINGO!!
I was looking at many threads related to this, but all predate my venture into Arduino-land. I don't know how bad things were 6+ years ago with the Arduinos. I wasn't here. I have been in and out of microcontroller programming for 20+ years so I have a running shot at learning and using the Arduinos. Most of my time is not learning but learning how to adapt what I did then to how it is done now. This is one of those cases.