I'd like to build my own Arduino clone board using the Atmega16u2 with a Atmega1284p but I'm having a hard time finding any firmware that supports both. This article makes it sound simple using Atmel Flip, but the filenames of the firmware indicate you have to choose one for a 328/16u2 or 2560/16u2 combo.
The 328 doesn't have enough GPIO for my project, but the 2560 is overkill. In doing research about flashing a 16u2, it seems as if the firmware is designed to work with only a few chips, and the 1284p is not one of them.
Considering the complexity involved with flashing brand new chips ordered online, I'm also leaning towards using a 1284p with an FTDI FT232, essentially building my own FTDI Basic into my board. Its design requires a continuous USB\Serial connection so I can send commands from a PC running nanpy (I'm coding everything in Python). I've successfully used an MCP2221A with an Atmega328 to control a board with nanpy, but now I want to be able to use SMD components and therefor I can't swap chips liked I use to do with my custom board and a official Uno to download sketches.
So my questions are: - Is it possible to use the 16u2 with the 1284p? - is there any advantage to using either the 16u2 over the FT232? Or vice versa? - Can I use Atmel Flip to flash everything? Or do I need AvrDude?
BTW, I'm new to flashing and bootloading fresh chips. I've only ever bought pre-flashed 328s to build the one Arduino board I've made. But I'm at the point where I need to make changes to the design and upgrade to the 1284. But I'm unsure if it's possible.
Worse case scenario is I just use the 2560. But that takes up more board space and cost more than a 1284p.
Any advice would be appreciated.