Section 11 Direct Memory Access Controller (DMAC)
Rev. 2.00 Mar 09, 2006 page 492 of 906
REJ09B0292-0200
•
Burst Mode
In burst mode, once the DMAC gets the bus, the transfer continues until the transfer end
condition is satisfied. When external request mode is used with level detection of the DREQ
pin, however, negating DREQ will pass the bus to the other bus master after completion of the
bus cycle of the DMAC that currently has an acknowledged request, even if the transfer end
conditions have not been satisfied. When the transfer request source is an on-chip peripheral
module, however, cycle-steal mode is always used.
Figure 11.11 shows an example of DMA transfer timing in burst mode. The transfer conditions
for the example in the figure are as shown below.
CPU
CPU
CPU
DMAC DMAC DMAC DMAC
CPU
DREQn
• Single address mode
• DREQn level detection
Bus
cycle
CPU
CPU
Figure 11.11 DMA Transfer Timing in Burst Mode (Single Address, DREQn Falling-Edge
Detection)
Refreshes cannot be performed during a burst transfer, so ensure that the number of transfers
satisfies the refresh request period when a memory requiring refreshing is used. When the transfer
request source is an external request (DREQn) in burst mode, set the DS bit of CHCR0 and
CHCR1 to 1 (edge detection). If the DS bits of CHCR0 and CHCR1 are set to 0 (level detection),
operation is not guaranteed.
Содержание SH7616
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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 ...