I got an EyeFi card for Christmas. It's a wonderful little device. But, sadly, it doesn't come with any software for Linux. I intend to see what I can do to change that. I'd at least like to be able to scan for and add new access points without rebooting into Windows. I'd also like to be able to have it dump its pictures on my Linux PCs instead of uploading to other servers, but that's a way down the line.
The card itself has a number of files on it:
$ find /media/EYE-FI/EyeFi/
These are how the EyeFi Manager communicates with the card. I think the filenames stand for REQuest or ReSPonse (for the first part of the filename) and Message or Code (for the last character). They are each apparently 16k in size.
From what I can glean so far, the manager starts by making sure the files are there, then zeroing them out. It then writes a command to reqm. I think those commands are single characters because the log has things like this in them:
[00:19] Host control channel received command 'o' (0x6f).
It also writes a character after those command characters, and that's where it starts to get murky. I'll post some more about that tomorrow. In the mean time, if anyone knows anything more about this card, please contact me.