Digi NS7520B-1-C36 Hardware Reference Manual page 139

DMA Module
C H A P T E R
T
he NS7520 supports 13 DMA channels. Each channel moves blocks of data between
memory and a memory peripheral. Each block transfer is defined by a descriptor of
two words (memory-to-peripheral) or three words (memory-to-memory) in circular
buffers maintained by the CPU. As each block transfer completes, the CPU need
update only the descriptor for the completed block transfer, minimizing CPU
intervention.
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