R01UH0823EJ0100 Rev.1.00
Page 367 of 1823
Jul 31, 2019
RX23W Group
18. DMA Controller (DMACA)
18.3.4
Activation Sources
Software, the interrupt requests from the peripheral modules, and the external interrupt requests can be specified as the
DMAC activation sources. Setting the DCTG[1:0] bits in DMTMD of DMACm selects the activation source.
(1) DMAC Activation by Software
Setting the DCTG[1:0] bits in DMTMD of DMACm to 00b enables the DMAC activation by software.
To start DMA transfer by software, set the DCTG[1:0] bits in DMTMD of DMACm to 00b, and then set the DTE bit in
DMCNT of DMACm to 1 (DMA transfer is enabled) and the SWREQ bit in DMREQ of DMACm to 1 (DMA transfer is
requested) with the DMST bit in DMAST set to 1 (DMAC activation enabled).
When the DMAC is activated by software while the CLRS bit in DMREQ of DMACm is 0, the SWREQ bit in DMREQ
of DMACm is cleared to 0 after data transfer is started in response to a DMA transfer request.
When the DMAC is activated by software while the CLRS bit is 1, the SWREQ bit is not cleared to 0 after data transfer
is started. In this case, a DMA transfer request is issued again after completion of a transfer.
(2) DMAC Activation by Interrupt Requests from On-Chip Peripheral Modules or External Interrupt
Requests
Interrupt requests from the on-chip peripheral modules and external interrupt requests can be specified as the DMAC
activation sources. The activation source can be selected separately for each channel using the DMRSRm registers (m =
0 to 3) of the ICU.
The DMAC is activated when an interrupt request from the on-chip peripheral module or an external interrupt request is
generated while the DCTG[1:0] bits in DMTMD of DMACm is set to 01b (interrupts from the peripheral modules and
the external interrupt pins are selected), the DTE bit in DMCNT of DMACm is set to 1 (DMA transfer is enabled), and
the DMST bit in DMAST is set to 1 (DMAC activation is enabled).
For interrupt requests specified as DMAC activation sources, see
Table 15.3, Interrupt Vector Table
, in