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STM32F439XX with video and external framebuffer

Question asked by pollack.brandon on Jan 13, 2015
Latest reply on Jan 15, 2015 by pollack.brandon
I can't seem to find more information on this, even looking through the EVAL code...

here it goes:  

I am designing a simple system to learn how to use the STM32F439XX and perhaps use it in future projects, but I am not sure if it is fast enough since the AHB can only support concurrent accesses to 1 external memory.

I am hoping to attach 128k of memory as a frame buffer at the beginning of this section of memory.  I already know there isn't enough time to render and fill (think a simple game like super mario world or something along those lines) the frame.

That said, I can attach 256k and double buffer by swapping the location of the buffer between frames, that gives me more than enough time to render each frame.

The problem occurs when I realized that I can't concurrently read from external memory for the frame buffer on FMC mapped SRAM/DRAM at the same time as writing to it.  Does anyone know if the contention will be a big problem?  I have never done something quite like this before, so I'm not sure on the details of sharing a bus (I know it's a round robin algorithm).

The pixel clock is 9 Mhz and system clock is whatever the minimum it needs to be to achieve ~60 fps (for debugging puruposes at the moment let's just say the maximum 180 Mhz).  I think the external memory will run at ~50 Mhz depending on which I buy.

Any suggestions are greatly appreciated.

Brandon

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