I'm trying to program an Adafruit Trinket using avr-gcc et. al. with the Makefile from the Bare-Arduino-Project on macOS Catalina.
I can build projects for standard boards like the Uno, but not for the Trinket. Everything works as expected using the "official" Arduino IDE (1.18.10). In the Bare-Arduino-Project Makefile I'm specifying the Trinket as:
BOARD_TAG = trinket5 BOARD_SUB = attiny85
I get an error from avr-gcc that mmcu is not defined. I assume this is because the command line tools aren't finding the Adafruit equivalent of boards.txt. When I look in the Arduino IDE package I don't find the Adafruit boards in boards.txt or anything that looks like the definitions for the Adafruit boards (despite having added them in the IDE).
Any ideas about how to set up support for the Trinket (or other third party boards) when using command line tools?