My experiments with various AVR chips I have with writing fairly bare bones blink programs.
Article on my website with some pictures
Inspiraion for the millis code is taken from MighyCore
This code should work on nearly any AVR, but I've only setup the code to work with (so far):-
ATtiny13
ATtiny84 - intresting pin layout compared to the rest!
ATtiny85
ATmega32a
ATmega328p
ATmega4809 - only fancy blink for now with separate source file. It's quite different to the rest.
The makefiles are setup for using a Raspberry PI which happens to permanently have a breadboard attached. I use GPIO 21 to control the reset pin, and the standard SCLK, MISO and MOSI pins.
Soon will come ATmega1284 (I doubt that will need much work)