R01UH0823EJ0100 Rev.1.00
Page 361 of 1823
Jul 31, 2019
RX23W Group
18. DMA Controller (DMACA)
18.3.2
Extended Repeat Area Function
The DMAC supports a function to specify the extended repeat areas on the transfer source and destination addresses.
With the extended repeat areas set, the address registers repeatedly indicate the addresses of the specified extended repeat
areas.
The extended repeat areas can be specified separately to the transfer source address register (DMSAR) and transfer
destination address register (DMDAR) of DMACm.
The extended repeat area on the source address is specified by the SARA[4:0] bits in DMAMD of DMACm. The
extended repeat area on the destination address is specified by the DARA[4:0] bits in DMAMD of DMACm. The size
can be specified separately for the source and destination sides.
However, the area (of transfer source or transfer destination) which is specified as the repeat area or block area should
not be specified as the extended repeat area.
When the address register value reaches the end address of the extended repeat area and the extended repeat area
overflows, DMA transfer is stopped and an interrupt by an extended repeat area overflow can be requested. When an
overflow occurs in the extended repeat area on the transfer source while the SARIE bit in DMINT of DMACm is set to 1,
the ESIF flag in DMSTS of DMACm is set to 1 and the DTE bit in DMCNT of DMACm is cleared to 0 to stop DMA
transfer. At this time, if the ESIE bit in DMINT of DMACm is set to 1, an interrupt by an extended repeat area overflow
is requested. When the DARIE bit in DMINT of DMACm is set to 1, the destination address register becomes a target to
apply the function. DMA transfer can be resumed by writing 1 to the DTE bit in DMCNT of DMACm in the interrupt
handling.
shows an example of the extended repeat area operation.
Figure 18.5
Example of Extended Repeat Area Operation
Example:
Eight bytes are specified as an extended repeat area by the lower three bits of DMACm.DMSAR (SARA[4:0]
bits in DMACm.DMAMD = 00011b).
The data size is eight bits (SZ[1:0] bits in DMACm.DMTMD = 00b).
Memory area
Repeat
00013FFEh
00013FFFh
00014000h
00014001h
00014002h
00014003h
00014004h
00014005h
00014006h
00014007h
00014008h
00014009h
00014000h
00014001h
00014002h
00014003h
00014004h
00014005h
00014006h
00014007h
An extended repeat area overflow interrupt
request can be generated.
DMSAR value
range