Section 11 Local Bus State Controller (LBSC)
Rev. 1.00 Oct. 01, 2007 Page 403 of 1956
REJ09B0256-0100
11.5.8
Wait Cycles between Accesses
A problem associated with higher operating frequencies for external memory buses is that the data
buffer turn-off after completion of a read from a low-speed device may be too slow, causing a
collision with the data in the next access, and resulting in lower reliability or malfunctions. To
prevent this problem, this module provides a data collision prevention function. It stores the
preceding access area and the type of read/write and inserts a wait cycle before the access cycle if
there is a possibility of a bus collision when the next access is started. The process for wait cycle
insertion consists of inserting idle cycles between the access cycles as shown in section 11.4.3,
CSn Bus Control Register (CSnBCR). If bits IWW, IWRWD, IWRWS, IWRRD and IWRRS in
CSnBCR (n
=
0 to 2 and 4 to 6) are used to set the number of idle cycles between accesses, the
number of inserted idle cycles is only the specified number of idle cycles minus the number of idle
cycles specified by the bits.
When bus arbitration is performed, the bus is released after wait cycles are inserted between the
cycles.
When a DMA transfer (dual address mode) is performed, wait cycles are inserted as set in
CSnBCR idle cycle bits.
When access the MPX interface area continuously after read access, 1 wait cycle is inserted even
if set the wait cycle to 0.
When the access size is 8-byte or 16-byte, wait cycles are inserted every 4-byte access.
Содержание SH7763
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Страница 122: ...Section 2 Programming Model Rev 1 00 Oct 01 2007 Page 56 of 1956 REJ09B0256 0100 ...
Страница 144: ...Section 3 Instruction Set Rev 1 00 Oct 01 2007 Page 78 of 1956 REJ09B0256 0100 ...
Страница 170: ...Section 4 Pipelining Rev 1 00 Oct 01 2007 Page 104 of 1956 REJ09B0256 0100 ...
Страница 282: ...Section 7 Caches Rev 1 00 Oct 01 2007 Page 216 of 1956 REJ09B0256 0100 ...
Страница 378: ...Section 9 Interrupt Controller INTC Rev 1 00 Oct 01 2007 Page 312 of 1956 REJ09B0256 0100 ...
Страница 514: ...Section 12 DDR SDRAM Interface DDRIF Rev 1 00 Oct 01 2007 Page 448 of 1956 REJ09B0256 0100 ...
Страница 630: ...Section 13 PCI Controller PCIC Rev 1 00 Oct 01 2007 Page 564 of 1956 REJ09B0256 0100 ...
Страница 686: ...Section 14 Direct Memory Access Controller DMAC Rev 1 00 Oct 01 2007 Page 620 of 1956 REJ09B0256 0100 ...
Страница 710: ...Section 16 Clock Pulse Generator CPG Rev 1 00 Oct 01 2007 Page 644 of 1956 REJ09B0256 0100 ...
Страница 732: ...Section 17 Watchdog Timer and Reset WDT Rev 1 00 Oct 01 2007 Page 666 of 1956 REJ09B0256 0100 ...
Страница 752: ...Section 18 Power Down Mode Rev 1 00 Oct 01 2007 Page 686 of 1956 REJ09B0256 0100 ...
Страница 772: ...Section 19 Timer Unit TMU Rev 1 00 Oct 01 2007 Page 706 of 1956 REJ09B0256 0100 ...
Страница 824: ...Section 21 Compare Match Timer CMT Rev 1 00 Oct 01 2007 Page 758 of 1956 REJ09B0256 0100 ...
Страница 1060: ...Section 23 Gigabit Ethernet Controller GETHER Rev 1 00 Oct 01 2007 Page 994 of 1956 REJ09B0256 0100 ...
Страница 1062: ...Section 24 IP Security Accelerator SECURITY Rev 1 00 Oct 01 2007 Page 996 of 1956 REJ09B0256 0100 ...
Страница 1124: ...Section 26 I 2 C Bus Interface IIC Rev 1 00 Oct 01 2007 Page 1058 of 1956 REJ09B0256 0100 ...
Страница 1184: ...Section 27 Serial Communication Interface with FIFO SCIF Rev 1 00 Oct 01 2007 Page 1118 of 1956 REJ09B0256 0100 ...
Страница 1350: ...Section 30 SIM Card Module SIM Rev 1 00 Oct 01 2007 Page 1284 of 1956 REJ09B0256 0100 ...
Страница 1484: ...Section 33 Audio Codec Interface HAC Rev 1 00 Oct 01 2007 Page 1418 of 1956 REJ09B0256 0100 ...
Страница 1560: ...Section 35 USB Host Controller USBH Rev 1 00 Oct 01 2007 Page 1494 of 1956 REJ09B0256 0100 ...
Страница 1720: ...Section 37 LCD Controller LCDC Rev 1 00 Oct 01 2007 Page 1654 of 1956 REJ09B0256 0100 ...
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