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BF548 EPPI DMA congestion

Question asked by gideon on Apr 17, 2012

I'm using a BF548EZkit to read a 16bit sensor on EPPI1 at 4MHz in continuous descriptor ring DMA mode, processing the data and feeding the results to the LCD on EPPI0 by DMA in autobuffer mode with 18 bits (at 133MHz/7 = 19MHz). I get FIFO overrun/underrun on both EPPIs, made worse if I write more stuff to the LCD framebuffer. I have tried everything in EE324 with no success, the only thing that works is to reduce the DMA bandwidth by feeding the LCD with just 6 bits, which allows packing four pixels into 32bit word, but then everything appears red on the LCD as I am then only driving the R of RGB. Any suggestions?