HD6417320 RENESAS [Renesas Technology Corp], HD6417320 Datasheet - Page 493

• Manufacturer Part Number: HD6417320
• Description: Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7700 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

10.4.3
When the DMAC receives simultaneous transfer requests on two or more channels, it transfers
data according to a predetermined priority. Two modes (fixed mode and round-robin mode) are
selected by the PR1 and PR0 bits in DMAOR.
(1)
In this mode, the priority levels among the channels remain fixed. There are two kinds of fixed
modes as follows:
• CH0 > CH1 > CH2 > CH3 > CH4 > CH5
• CH0 > CH2 > CH3 > CH1 > CH4 > CH5
These are selected by the PR1 and the PR0 bits in DMAOR.
(2)
In round-robin mode each time data of one transfer unit (word, byte, longword, or 16-byte unit) is
transferred on one channel, the priority is rotated. The channel on which the transfer was just
finished rotates to the bottom of the priority. The round-robin mode operation is shown in figure
10.3. The priority of round-robin mode is CH0 > CH1 > CH2 > CH3 > CH4 > CH5 immediately
after a reset. When round-robin mode is specified, the same bus mode, either cycle steal mode or
burst mode, must be specified for all of the channels.
Fixed Mode
Round-Robin Mode
Channel Priority
Section 10
Rev. 3.00 Jan. 18, 2008 Page 431 of 1458
Direct Memory Access Controller (DMAC)
REJ09B0033-0300