After my previous post which detailed the process for getting a bootloader and firmware installed on an ATmega 1284P in a set of Sanguinololu electronics we have been printing solidly for the last week using this setup, with great success or rather, no difference at all from the 644P.
This was what we hoped and expected; we are using the stock settings in Sprinter for a Sanguinololu which work fine for a 644P and demonstratively for the 1284P as well.
So why bother?
The answer lies in our desire to expand the capabilities of the Sanguinololu by allowing it to interface with an LCD screen. This is currently not a default feature in Sprinter but it is included in Marlin so we are going to switch to using Marlin for a bit and get to grips with how that works and is configured.
An example of a LCD screen and input option that is available right now and working for RAMPS is the "PanelMax", a neat solution that uses RP parts as well as a 20x4 LCD screen, and a rotary encoder for input. The ATmega2560 has more I/O pins than the Sanguinololu so it may be a challenge to use the same method. I am going to throw together a bread board circuit in the next couple of days when my LCD and click encoder arrive and will post with an update.