Once in a while I check the optiboot project and I’m glad to see it’s active. Today I saw version 5.0a had been released some weeks ago and so I thought it was due time to recompile and replace it on my toy board.

Let’s review the official instructions:

• I don’t have a single Windows system, so I cannot say anything about that world;
• for Mac, if you use MacPorts you don’t need CrossPack: just install the avr-libc port (if you use Homebrew, you’ll have to search for a good formula);
• for Linux (let’s say a Xubuntu 13.04 for argument’s sake), you need to install the avr-libc package (which depends on the gcc-avr package; if you installed only the latter, you wouldn’t be able to build the bootloader).

Official instructions hint to use Arduino IDE’s AVR GCC: I’ve never been able to make it works and it’s older than what can be installed on Mac and Linux, so let’s forget it (and after all, setting up a minimalistic local development environment is not so hard, isn’t it?).

Anyway, after you have a working compiler, it’s just a matter of running make with the right target; and given that these days UARTs are configurable, building a bootloader which uses another UART is a breeze:

Awesome!