I have several ov7670 camera modules, some with Fifo. I have not started to get it working with my Arduino Due, but know the 790(!) posting thread on that subject:
http://forum.arduino.cc/index.php?topic=159557.0Since I want to use camera for high speed autonomous robot control (
Arduebot) I need high fps pictures sent to Due (the other Arduinos are no options because of lack of horse power). Pictures will be simple b&w, no high resolution is needed (80x60 or even 40x30 might be OK). Camera will be mounted sloped and take pictures from front of Arduebot (the "present") until a little ahead (in order to capture the "near future"):

I recently found this easier instruction on how to connect ov7670 with Arduino Due, and was able to understand what was stated there in Russian with the help of Google Translate:
http://privateblog.info/arduino-due-i-kamera-ov7670-primer-ispolzovaniya/So I think that Due+ov7670 will do the job needed.
Recently I bought Raspberry Pi Zero for 5$(+5$ shipping). It has a camera connector, but only for >35$ cameras. Yesterday I googled and found this really simple instruction on how to use a simple USB webcam with Raspberry Pi:
https://www.youtube.com/watch?v=JnQh-o9aSD0So I bought a
2$ USB webcam and a
0.31$ micro USB to USB connector yesterday, both with free shipping. This will give me a 1GHz 512MB memory camera "coprocessor" for less than 12.50$.
Pi Zero will only transmit the needed data to Arduino Due and that will use the data to decide on motor speed corrections.
I can think of other uses of Pi Zero as high performance coprocessor, and not only for Arduino Due. Transmitting the data should not be difficult given the 40 GPIO pins of Pi Zero.
Am I right with this "Pi Zero as coprocessor" approach, or do I miss some important fact?
Hermann.