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In Block Transfer Mode, the DMAC transfers an entire block of data from the source to the destination area. At each request, the DMAC transfers a block of data. The data within the block can be 8-, 16-, or 32-bit values. As with the other modes, the source & destination address registers keep track of where to move the data from and to. The updates to the source & destination addresses happen as each data item is moved during the block transfer, so if the source or destination address was set to increment, then at the end of the block transfer it will point to the first data item after the block. The source or the destination can be specified as the block area, and the size of the block area can be up to 1K. In this example, the destination is the block area and the block size is 3. A transfer counter is used internally by the DMAC as it transfers each block; it must be initialized to the block size. A separate block count is decremented each time the DMAC is triggered and a block is transferred. The address register of the block area resets to the start of the block area after each transfer. When the block counter reaches zero, the transfer ends and an interrupt can be generated to the CPU. An interrupt may also be generated at each block transfer.
