
9
9-17
Rev.1.0
The DMA Channel Control Register consists of a bit to select DMA transfer mode for each channel,
set DMA transfer request flag, and the bits to select the cause of DMA request, enable a DMA
transfer, set the transfer size, and source/destination address directions.
(1) MDSELn (DMAn transfer mode select) bit (D0)
This bit when in single transfer mode selects normal or ring buffer mode. Setting this bit to 0
selects normal mode, and setting this bit to 1 selects ring buffer mode.
In ring buffer mode, operation starts from the transfer start address and when transferred 32
times, returns to the transfer start address again, from which transfer operation restarts. In this
case, the transfer count register operates in free-running mode, so that transfer operation is
continued until the transfer enable bit is set to 0 (to disable transfer). No DMA transfer-finished
interrupts are generated.
(2) TREQFn (DMAn transfer request flag) bit (D1)
This flag is set to 1 when a DAM transfer request occurs. Reading this flag helps to know whether
there is a DMA transfer request on any channel.
The DMA transfer request is cleared by writing 0 to this bit. Writing 1 has no effect, the bit retains
the value it had before writing.
Even when a new DMA transfer request occurs for a channel whose DMA transfer request flag is
already set to 1, the next DMA transfer request is not accepted until after a transfer on the
channel is completed.
(3) REQSLn (cause of DMAn request select) bits (D2, D3)
These bits select the cause of DMA request on each DMA channel.
Note: If "Extended request cause" is selected for the cause of DMA request, always be sure to
set the DMA Request Extended Cause Register to select a DMA request extended
cause.
(4) TENLn (DMAn transfer enable) bit (D4)
Setting this bit to 1 enables transfer, making a DMA transfer ready to run. Setting this bit to 0
disables transfer. However, if a transfer request has already been accepted, transfer is not
disabled until after the requested transfer is completed.
(5) TSZSLn (DMAn transfer size select) bit (D5)
This bit selects the number of data bits to be transferred in one DMA transfer operation (unit of
one transfer). The unit of one transfer is 16 bits when this bit = 0, or 8 bits when this bit = 1.
(6) SADSLn (DMAn source address direction select) bit (D6)
This bit selects the direction in which the source address changes from two modes available:
address fixed or address increment.
(7) DADSLn (DMAn destination address direction select) bit (D7)
This bit selects the direction in which the destination address changes from two modes available:
address fixed or address increment.
DMAC
9.2 DMAC Related Registers