SGDMA descriptor questions

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You will need to use two descriptors to move 65kB of memory, descriptors only have a 16-bit length field so that means you can only write up to 65535 bytes total. So it's not that the memory is write protected, the SGDMA just can't write that much data using a single descriptor.

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I was using a chains of descriptors, not just 1. I know 1 DMA transaction can move 65KB of data, so i used a chains of 4 DMA transaction to move 16384 bytes each time, so i can move 4*16384=65536 Bytes, but still some ranges of memory address in the destination RAM is not writable, as shown in the picture

Michael