Hi,
I'm working in a project that should realize a usb mass storage device usingOMAPL138 usb2.0 module. I've designed two kind of board with the same schematic but different PCB. One of them provides 20MHz clock to OMAPL138, and the other one provides 40MHz. The former works well whether writing or reading a file from the mass storage, but the latter can only read files.
I used CPU for transforming but CPPI DMA, and found that every time the PC send a packet of data larger than 512 bytes( the FIFO size), the CPU can only get 512 bytes from the FIFO, then no interrupt occurred. Dose it mean i have to use CPPI DMA when the packet size may be larger than the FIFO size? And what confused is why one of my board with the same schematic and programming(of course the usb2.0 controller was configured for different clock frequency) can works well.
Thanks,
Huang.
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