Section 8 Bus State Controller (BSC)
Rev. 5.00 May 29, 2006 page 248 of 698
REJ09B0146-0500
T1
CKIO
CSm
CSn
A25 to A0
BS
RD/
WR
RD
D31 to D0
T2
Twait
T1
T2
Twait
T1
T2
Area m read
Area m inter-access wait specification
Area n inter-access wait specification
Area n space read
Area n space write
Figure 8.39 Waits between Access Cycles
8.5.8
Bus Arbitration
When a bus release request (
BREQ
) is received from an external device, buses are released after
the bus cycle being executed is completed and a bus grant signal (
BACK
) is output
.
The bus is not
released during burst transfers for cache fills or a write back and TAS instruction execution
between the read cycle and write cycle. Bus arbitration is not executed in multiple bus cycles that
are generated when the data bus width is shorter than the access size; i.e. in the bus cycles when
longword access is executed for the 8-bit memory. At the negation of
BREQ
,
BACK
is negated
and bus use is restarted
.
See Appendix B, Pin Functions, for the pin state when the bus is released.
This LSI sometimes needs to retrieve a bus it has released. For example, when memory generates
a refresh request or an interrupt request internally, this LSI must perform the appropriate
processing. This LSI has a bus request signal (
IRQOUT
) for this purpose. When it must retrieve
the bus, it asserts the
IRQOUT
signal. Devices asserting an external bus release request receive the
assertion of the
IRQOUT
signal and negate the
BREQ
signal to release the bus. This LSI retrieves
the bus and carries out the processing.
Содержание SH7706 Series
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Страница 160: ...Section 5 Cache Rev 5 00 May 29 2006 page 112 of 698 REJ09B0146 0500 ...
Страница 370: ...Section 11 Watchdog Timer WDT Rev 5 00 May 29 2006 page 322 of 698 REJ09B0146 0500 ...
Страница 532: ...Section 16 Serial Communication Interface with FIFO SCIF Rev 5 00 May 29 2006 page 484 of 698 REJ09B0146 0500 ...
Страница 554: ...Section 17 Pin Function Controller PFC Rev 5 00 May 29 2006 page 506 of 698 REJ09B0146 0500 ...
Страница 576: ...Section 18 I O Ports Rev 5 00 May 29 2006 page 528 of 698 REJ09B0146 0500 ...
Страница 614: ...Section 21 User Debugging Interface H UDI Rev 5 00 May 29 2006 page 566 of 698 REJ09B0146 0500 ...
Страница 746: ...Index Rev 5 00 May 29 2006 page 698 of 698 REJ09B0146 0500 ...
Страница 749: ...SH7706 Group Hardware Manual ...