Being a proprietary interface means that even entry-level programmers ... if UDPI AVR support with the Snap is really an afterthought for Microchip. Meanwhile there are also more DIY solutions ...

Enter TPI (tiny programming interface), and exit all of your previously useful DIY AVR programmers. [Kimio Kosaka] wrote a dual-purpose TPI and ISP firmware for the ATmegaxxUn chips that are used ...