Last time, I presented a working proof-of-concept of a digital compass based on a three-axis magnetometer. That version was running in userland on a Raspberry Pi running Raspbian, which is a whole lot more computer than the Atmel ATtiny85 I eventually want to target. It was also coded for clarity rather than for speed or size.
In this post, I'll look at some quick-and-dirty ways to estimate program size for an AVR version (as well as some simple things we can do to save space). Read on for more.