This article was previously published on lhexapod.com as part of my journey of discovery into robotics and embedded assembly programming. A full index of these articles can be found here.
This is the source code for the latest version of the 64 channel servo controller as detailed here.
The schematic required is similar to the one for the ATtiny2313, I’ll produce a new one for the ATMega168 when I get some time. Note that we now use pins 0-3 of port B and port C rather than just 0-7 on port B, so the connections for mux chips 5 through 8 will come off of port C.
Source code is available here.