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DMA controller structure
The DMA controller usually has 5 registers:
- block length register
- source address register
- destination address register.
- byte counter
- a temporary data register
The user initializes the first three registers, then starts the DMA process.
DMA usually has five registers: a block length register, a source address register, a destination address register, a byte counter, and a temporary data register.
The block length register indicates the transfer block size. The source address register holds the source address for the next byte/word transfer. The destination address register holds the destination address for the next byte/word transfer. The byte counter keeps track of how many bytes have been transferred. The temporary data register holds the data after reading it from the source and before sending the data to the destination. The user can initialize the block length register, source address register, and destination address register and start the DMA process.
Some DMA controllers support several DMA processes. These DMA controllers have additional control registers to handle scheduling and priority of multiple DMA operations.