RX610 Group
12. DMA Controller (DMAC)
R01UH0032EJ0120 Rev.1.20
Page 301 of 1006
Feb 20, 2013
12.
DMA Controller (DMAC)
The RX610 Group incorporates a 4-channel direct memory access controller (DMAC).
The DMAC is a module to transfer data without the CPU.
When a DMA transfer request is generated, the DMAC transfers data stored at the transfer source address to the transfer
destination address.
12.1
Overview
Table 12.1 lists the specifications of the DMAC, and figure 12.1 shows a block diagram of the DMAC.
Table 12.1 Specifications of DMAC
Item
Description
Number of channels
4 (DMACm (m = 0 to 3))
Transfer space
4 Gbytes (00000000h to FFFFFFFFh excluding reserved areas)
Maximum transfer volume
64 Mbytes
DMA activation source
Software trigger
Trigger input to external pin interrupts
Interrupt requests from peripheral functions
Channel priority
Channel 0
>
Channel 1
>
Channel 2
>
Channel 3 (Channel 0: Highest)
Transfer
data
Single data
Bit length: 8, 16, 32 bits
Single operand
Data count: 1, 2, 4, 8, 16, 32, 64, 128
Transfer
system
Operand transfer
system
Single
Data of a single operand is transferred per DMA transfer
request.
Channel arbitration is made after a single-operand transfer.
A DMA transfer request is necessary at each end of
single-operand transfer until the DMA transfer end.
Consecutive
Data is transferred continuously in operand units until the DMA
transfer end per DMA transfer request.
Channel arbitration is made after a single-operand transfer.
A DMA transfer request is made first only once.
Nonstop transfer
system
Data is transferred continuously until the DMA transfer ends per DMA transfer
request.
Channel arbitration is made when DMA transfer is completed.
A DMA transfer request is made first only once.
DMA transfer start condition
DMA transfer starts when all the following conditions are met.
The DEN bit in DMCRE of DMACm is 1 (DMA transfer enabled).
The DMST bit in DMSCNT is 1 (DMAC start).
When a DMA transfer request of channel m (DMACm) is generated and the
execution authority is obtained by the channel arbitration.
DMA transfer end condition
When the DMCBC register of DMACm is decremented to 0000000h
Interrupt request generation timing
When the DMCBC register of DMACm is decremented to 0000000h
Single-data transfer time
Three bus clock cycles or more