HD6417706 RENESAS [Renesas Technology Corp], HD6417706 Datasheet - Page 307

• Manufacturer Part Number: HD6417706
• Description: Renesas 32-Bit RISC Microcomputer Super RISC engine Family/SH7700 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

Figure 9.4 shows how the priority order changes when channel 0 and channel 3 transfers are
requested simultaneously and a channel 1 transfer is requested during the channel 0 transfer. The
DMAC operates as follows:
1. Transfer requests are generated simultaneously to channels 0 and 3.
2. Channel 0 has a higher priority, so the channel 0 transfer begins first (channel 3 waits for
3. A channel 1 transfer request occurs during the channel 0 transfer (channels 1 and 3 are both
4. When the channel 0 transfer ends, channel 0 becomes lowest priority.
5. At this point, channel 1 has a higher priority than channel 3, so the channel 1 transfer begins
6. When the channel 1 transfer ends, channel 1 becomes lowest priority.
7. The channel 3 transfer begins.
8. When the channel 3 transfer ends, channels 3 and 2 shift downward in priority so that channel 3
transfer).
waiting)
(channel 3 waits for transfer).
becomes the lowest priority.
Transfer request
(1) Channels 0 and 3
(3) Channel 1
Figure 9.4 Changes in Channel Priority in Round-Robin Mode
Waiting channel(s)
1,3
3
3
None
(2) Channel 0 transfer
(4) Channel 0 transfer
(5) Channel 1 transfer
(6) Channel 1 transfer
(7) Channel 3 transfer
(8) Channel 3 transfer
start
ends
starts
ends
starts
ends
DMAC operation
Priority order
changes
Priority order
changes
Priority order
changes
Rev. 4.00, 03/04, page 261 of 660
Channel priority
0 > 1 > 2 > 3
1 > 2 > 3 > 0
2 > 3 > 0 > 1
0 > 1 > 2 > 3