R01UH0823EJ0100 Rev.1.00
Page 352 of 1823
Jul 31, 2019
RX23W Group
18. DMA Controller (DMACA)
18.2.10
DMA Software Start Register (DMREQ)
SWREQ Bit (DMA Software Start)
When 1 is written to this bit, a DMA transfer request is generated. After DMA transfer is started in response to the
request, this bit is cleared to 0 if the CLRS bit is set to 0. This bit is not cleared to 0 while the CLRS bit is set to 1. In this
case, a DMA transfer request can be issued again after completion of a transfer.
Note that, however, setting this bit is valid and DMA transfer by software is enabled only when the DCTG[1:0] bits in
DMTMD are set to 00b (DMA activation source is software).
Setting this bit is invalid when the DCTG[1:0] bits in DMTMD are set to a value other than 00b.
To start DMA transfer by software with the CLRS bit being 0, ensure that the SWREQ bit is 0, and then write 1 to the
SWREQ bit.
[Setting condition]
When 1 is written to this bit.
[Clearing conditions]
When a DMA transfer request by software is accepted and DMA transfer is started while the CLRS bit is set to 0
(the SWREQ bit is cleared after DMA transfer is started by software).
When 0 is written to this bit.
CLRS Bit (DMA Software Start Bit Auto Clear Select)
This bit specifies whether to clear the SWREQ bit to 0 after DMA transfer is started in response to the DMA transfer
request generated by setting the SWREQ bit to 1. With this bit set to 0, the SWREQ bit is cleared to 0 after DMA transfer
is started. With this bit set to 1, the SWREQ bit is not cleared to 0. In this case, a DMA transfer request can be issued
again after completion of a transfer.
Address(es): DMAC0.DMREQ 0008 201Dh, DMAC1.DMREQ 0008 205Dh, DMAC2.DMREQ 0008 209Dh, DMAC3.DMREQ 0008 20DDh
b7
b6
b5
b4
b3
b2
b1
b0
—
—
—
CLRS
—
—
—
SWRE
Q
Value after reset:
0
0
0
0
0
0
0
0
Bit
Symbol
Bit Name
Description
R/W
b0
DMA Software Start
0: DMA transfer is not requested.
1: DMA transfer is requested.
R/W
b3 to b1
—
Reserved
These bits are read as 0. The write value should be 0.
R/W
b4
DMA Software Start Bit Auto
Clear Select
0: SWREQ bit is cleared after DMA transfer is started by software.
1: SWREQ bit is not cleared after DMA transfer is started by software.
R/W
b7 to b5
—
Reserved
These bits are read as 0. The write value should be 0.
R/W