here is the code for initializing ov7670camera+fifo with mega2560
the only problem is deffrence in pinouts (version1 and version2)
the code is written for version1,but my camera has version2 pinouts
in this page
https://wiki.beyondlogic.org/index.php/OV7670_Camera_Module_with_AL422_FIFO_Theory_of_Operation
i could find guidance for edit in version2,but still not sure what should i change