R-IN32M3_15 Datasheet, PDF (45/105 Pages) Renesas Technology Corp – LSI for Industrial Ethernet

R-IN32M3 Series Data Sheet
3. Specifications
3.5 General DMA Controller
3.5.1
Features
- Instances : 4 channels (each channel is independent)
- Transfer data size
 Independently selectable source and destination size
 Size range: 8- bit to 512-bit
- Maximum number of transfer bytes : 2³²-1
- Channel priority control
 Fixed priority mode
 Round robin mode
- DMA Transfer methods
 Register mode :
DMA transfer is performed using the values set in the control registers of the DMA controller written by
the CPU. This mode supports conventional general DMA transfer.
 Link mode :
DMA transfer is performed according to a descriptor located in Data RAM and external memory. The
responsiveness of this mode is inferior to register mode because access of the descriptor occurs at every
DMA transfer.
- Skip function
Continuous access size and discrete access size can each be set for the areas that are accessed with DMA transfer.
Following access of the set size, it is possible to skip to the next address to be accessed.
- Intra-buffer data sweep function
The data in the buffer can be output when the DMAC is forcibly stopped. After sweeping, DMA transfers
continue sequentially.
- Suspend function
Execution of a DMA transaction can be paused (suspended).
- DMA transfers interval setting function
The interval between DMA transfers can be set in order to adjust the bus usage rate.
- Transfer mode
 Single transfer mode
When a DMA transfer request is acknowledged, the DMAC controls and then releases the bus once for
each transfer. Additional DMA requests are required for each subsequent transfer.
 Block transfer mode
When DMA transfer request is acknowledged, the DMAC takes control of the bus and repeats data
transmission until completion of the number of transfers indicated bhy the control register.. But this mode
does not occupy the bus.
Caution Please align data at 512-bit boundaries for 512-bit transfers.
R18DS0008EJ0204
Dec 25, 2014
Page 45 of 100