Section 11 Direct Memory Access Controller (DMAC)
Rev. 2.00 Mar 09, 2006 page 484 of 906
REJ09B0292-0200
CPU
Bus
cycle
DREQ1
DREQ0
CPU
CPU
CPU
CPU
Channel 0
source
Channel 1
source
Channel 0
source
Channel 0
destination
Channel 1
destination
Figure 11.4 Fixed Mode DMA Transfer in Cycle-Steal Mode
(Dual Address, DREQn Low-Level Detection)
Round-Robin Mode:
Switches the priority of channel 0 and channel 1, shifting their ability to
receive transfer requests. Each time one transfer ends on one channel, the priority shifts to the
other channel. The channel on which the transfer just finished is assigned low priority. After reset,
channel 1 has higher priority than channel 0.
Figure 11.5 shows how the priority changes when channel 0 and channel 1 transfers are requested
simultaneously and another channel 0 transfer is requested after the first two transfers end. The
DMAC operates as follows:
1. Transfer requests are generated simultaneously to channels 1 and 0.
2. Channel 1 has the higher priority, so the channel 1 transfer begins first (channel 0 waits for
transfer).
3. When the channel 1 transfer ends, channel 1 becomes the lower-priority channel.
4. The channel 0 transfer begins.
5. When the channel 0 transfer ends, channel 0 becomes the lower-priority channel.
6. A channel 0 transfer is requested.
7. The channel 0 transfer begins.
8. When the channel 0 transfer ends, channel 0 is already the lower-priority channel, so the order
remains the same.
Содержание SH7616
Страница 10: ...Rev 2 00 Mar 09 2006 page x of xxvi ...
Страница 132: ...Section 2 CPU Rev 2 00 Mar 09 2006 page 106 of 906 REJ09B0292 0200 ...
Страница 568: ...Section 12 16 Bit Free Running Timer FRT Rev 2 00 Mar 09 2006 page 542 of 906 REJ09B0292 0200 ...
Страница 582: ...Section 13 Watchdog Timer WDT Rev 2 00 Mar 09 2006 page 556 of 906 REJ09B0292 0200 ...
Страница 662: ...Section 14 Serial Communication Interface with FIFO SCIF Rev 2 00 Mar 09 2006 page 636 of 906 REJ09B0292 0200 ...
Страница 706: ...Section 16 Serial I O SIO Rev 2 00 Mar 09 2006 page 680 of 906 REJ09B0292 0200 ...
Страница 820: ...Section 19 Pin Function Controller PFC Rev 2 00 Mar 09 2006 page 794 of 906 REJ09B0292 0200 ...
Страница 932: ...Appendix D Package Dimensions Rev 2 00 Mar 09 2006 page 906 of 906 REJ09B0292 0200 ...
Страница 935: ...SH7616 Hardware Manual ...