SH7261 Datasheet, PDF (390/1348 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7260 Series

Section 11 Direct Memory Access Controller (DMAC)
11.6 Suspending, Restarting, and Stopping of DMA Transfer
11.6.1 Suspending and Restarting DMA Transfer
Transfer on all channels of the DMAC can be suspended by clearing the DMST bit in the DMA
activation control register (DMSCNT) to "0". Transfer on a specific channel can also be
suspended by clearing the DMA transfer enable bit (DEN) in DMA control register B
(DMCNTBn) for that channel.
If the DMST bit or the corresponding DEN bit is cleared to "0" while single operand transfer or
sequential operand transfer is in progress, transfer is suspended on completion of the current single
operand transfer regardless of the transfer mode (whether transfer is in cycle-stealing or pipelined
mode).
When transfer in the non-stop transfer condition is in progress, DMA transfer is not suspended and
continues to completion (until the byte counter reaches "0") even if the DMST bit or
corresponding DEN bit is cleared to "0".
To restart DMA transfer on a channel for which transfer has been suspended, set (to "1")
whichever of DMST and the corresponding DEN bit has been cleared.
11.6.2 Stopping DMA Transfer on Any Channel
To stop transfer on any channel, suspend transfer on that channel and then initialize the interior
state of the DMAC for that channel by setting the DMAC internal state clear bit (DSCLR) in the
corresponding DMA control register B (DMCNTBn). In this case, only the transfer state of the
DMAC internal circuits is initialized; the registers retain their values.
Rev. 2.00 Sep. 07, 2007 Page 358 of 1312
REJ09B0320-0200