
Section 13 Direct Memory Access Controller (DMAC)
Rev. 4.00 Sep. 14, 2005 Page 437 of 982
REJ09B0023-0400
Figure 13.9 shows an example of DMA transfer timing in the cycle steal mode. Transfer
conditions shown in the figure are:
1. Dual address mode
2.
DREQ
low level detection
CPU
CPU
CPU
DMAC DMAC
CPU
DMAC DMAC
CPU
DREQ
Bus cycle
Bus mastership returned to CPU once
Read/Write
Read/Write
Figure 13.9 DMA Transfer Example in the Cycle-Steal Normal Mode
(Dual Address,
DREQ
Low Level Detection)
•
Intermittent Mode 16 and Intermittent Mode 64
In the intermittent mode of cycle steal, DMAC returns the bus mastership to other bus master
whenever a unit of transfer (byte, word, longword, or 16 bytes) is complete. If the next transfer
request occurs after that, DMAC gets the bus mastership from other bus master after waiting
for 16 or 64 clocks in B
φ
count. DMAC then transfers data of one unit and returns the bus
mastership to other bus master. These operations are repeated until the transfer end condition is
satisfied. It is thus possible to make lower the ratio of bus occupation by DMA transfer than
the normal mode of cycle steal.
When DMAC gets again the bus mastership, DMA transfer can be postponed in case of entry
updating due to cache miss.
This intermittent mode can be used for all transfer section; transfer requester, source, and
destination. The bus modes, however, must be cycle steal mode in all channels.
Figure 13.10 shows an example of DMA transfer timing in cycle steal intermittent mode. Transfer
conditions shown in the figure are:
1. Dual address mode
2.
DREQ
low level detection
Содержание HD6417641
Страница 2: ...Rev 4 00 Sep 14 2005 Page ii of l...
Страница 7: ...Rev 4 00 Sep 14 2005 Page vii of l...
Страница 11: ...Rev 4 00 Sep 14 2005 Page xi of l USB Universal serial bus WDT Watch dog timer...
Страница 12: ...Rev 4 00 Sep 14 2005 Page xii of l...
Страница 28: ...Rev 4 00 Sep 14 2005 Page xxviii of l...
Страница 204: ...Section 4 Clock Pulse Generator CPG Rev 4 00 Sep 14 2005 Page 154 of 982 REJ09B0023 0400...
Страница 212: ...Section 5 Watchdog Timer WDT Rev 4 00 Sep 14 2005 Page 162 of 982 REJ09B0023 0400...
Страница 228: ...Section 6 Power Down Modes Rev 4 00 Sep 14 2005 Page 178 of 982 REJ09B0023 0400...
Страница 246: ...Section 8 X Y Memory Rev 4 00 Sep 14 2005 Page 196 of 982 REJ09B0023 0400...
Страница 318: ...Section 11 User Break Controller UBC Rev 4 00 Sep 14 2005 Page 268 of 982 REJ09B0023 0400...
Страница 454: ...Section 12 Bus State Controller BSC Rev 4 00 Sep 14 2005 Page 404 of 982 REJ09B0023 0400...
Страница 500: ...Section 13 Direct Memory Access Controller DMAC Rev 4 00 Sep 14 2005 Page 450 of 982 REJ09B0023 0400...
Страница 504: ...Section 14 U Memory Rev 4 00 Sep 14 2005 Page 454 of 982 REJ09B0023 0400...
Страница 566: ...Section 17 Compare Match Timer CMT Rev 4 00 Sep 14 2005 Page 516 of 982 REJ09B0023 0400...
Страница 734: ...Section 18 Multi Function Timer Pulse Unit MTU Rev 4 00 Sep 14 2005 Page 684 of 982 REJ09B0023 0400...
Страница 868: ...Section 21 A D Converter Rev 4 00 Sep 14 2005 Page 818 of 982 REJ09B0023 0400...
Страница 914: ...Section 23 I O Ports Rev 4 00 Sep 14 2005 Page 864 of 982 REJ09B0023 0400...
Страница 956: ...Section 24 List of Registers Rev 4 00 Sep 14 2005 Page 906 of 982 REJ09B0023 0400...
Страница 1016: ...Section 25 Electrical Characteristics Rev 4 00 Sep 14 2005 Page 966 of 982 REJ09B0023 0400...
Страница 1024: ...Appendix Rev 4 00 Sep 14 2005 Page 974 of 982 REJ09B0023 0400...
Страница 1032: ...Rev 4 00 Sep 14 2005 Page 982 of 982 REJ09B0023 0400 X X Y data addressing 52 X Y memory 193...
Страница 1035: ......
Страница 1036: ...SH7641 Hardware Manual...