Honored Contributor
Honored ContributorNot really much help, but simply confirming your suspicions:
Yes, you will end up having to re-implement basically all of the functionality embedded within the Frame Buffer. Stream-in, Stream-out, and Avalon-MM Master bursting read/write. Because your external memory is only efficient when bursting, you will need to manage an onchip cache such that you can burst many pixels at a time, and store them onchip until they are needed. 180 degrees is relatively easy in that you simply burst read from the memory and then output the pixels in reverse order from within that burst. +/- 90 is more complicated in that you need to read a burst from each row and cache the contents of each burst until all of the pixels have been output (i.e. you need 480x the amount of onchip RAM dedicated to caching than you do in the 180 degree case). Assuming you're in a device with adequate memory capacity, it is overall not a particularly hard function to implement, but some care is needed at the higher pixel rates and/or higher utilization of the external memory, none of which sounds problematic for you.
