If the camera is still working and connected to the rest of the phone, I'd start by probing the pins with a scope to identify which pin is what, and then hooking up a logic analyzer to try and make sense of the data. It's not going to be easy.
Can you find a schematic of the phone that yours is a clone of, or a similar one? That can help with the pinout. You will likely find that the camera doesn't interface directly with the memory card, and that any ATMega part is way too slow for the job, especially at 3.3v or less.
If you are trying to interface a camera, I'd start by getting one that comes with a proper datasheet and uses a slower standard interface (serial, USB) to transfer the data.
Also, please review
this document
/mike