R01UH0823EJ0100 Rev.1.00
Page 372 of 1823
Jul 31, 2019
RX23W Group
18. DMA Controller (DMACA)
(6) DMA Active Flag (DMACm.DMSTS.ACT)
The ACT bit in DMSTS of DMACm indicates whether the DMACm is in the idle or active state.
This flag is set to 1 when the DMAC starts data transfer, and is cleared to 0 when data transfer in response to one transfer
request is completed.
Even when DMA transfer is stopped by writing 0 to the DTE bit in DMCNT of DMACm during DMA transfer, this flag
remains 1 until DMA transfer is completed.
(7) Transfer End Interrupt Flag (DMACm.DMSTS.DTIF)
The DTIF flag in DMSTS of DMACm is set to 1 after DMA transfer of the total transfer size of data is completed.
When both this flag and the DTIE bit in DMINT of DMACm are set to 1, a transfer end interrupt is requested.
This flag is set to 1 when the DMA transfer bus cycle is completed and the ACT flag in DMSTS of DMACm is cleared
to 0 indicating the DMA transfer end.
This flag is automatically cleared to 0 when the DTE bit in DMCNT of DMACm is set to 1 during the interrupt handling.
(8) Transfer Escape End Interrupt Flag (DMACm.DMSTS.ESIF)
The ESIF flag in DMSTS of DMACm is set to 1 when a repeat size end interrupt or extended repeat area overflow
interrupt is requested. When this bit and the ESIE bit in DMINT of DMACm are set to 1, a transfer escape end interrupt
is requested.
This flag is set to 1 when the bus cycle of the DMA transfer having caused the interrupt request is completed and the
ACT flag in DMSTS of DMACm is cleared to 0 indicating the DMA transfer end.
This flag is automatically cleared to 0 when the DTE bit in DMCNT of DMACm is set to 1 during an interrupt handling.
Before sending an interrupt request from the DMAC to the CPU or the DTC, the interrupt control register must be set.
For details, see
section 15, Interrupt Controller (ICUb)
18.3.10
Channel Priority
When multiple DMA transfer requests are present, the DMAC determines the priority of channels that have DMA
transfer requests.
The channel priority is fixed as channel 0 > channel 1 > channel 2 > channel 3 (channel 0: highest).
When a DMA transfer request is generated during data transfer, channel arbitration is started after the final data has been
transferred, and DMA transfer of the higher-priority channel starts.