Section 8 Bus State Controller (BSC)
Rev. 5.00 May 29, 2006 page 234 of 698
REJ09B0146-0500
8.5.5
Burst ROM Interface
Setting bits A0BST (1 to 0), A5BST (1 to 0), and A6BST (1 to 0) in BCR1 to a non-zero value
allows burst ROM to be connected to areas 0, 5, and 6. The burst ROM interface provides high-
speed access to ROM that has a nibble access function. The timing for nibble access to burst ROM
is shown in figure 8.28. Two wait cycles are set. Basically, access is performed in the same way as
for normal space, but when the first cycle ends the
CS0
signal is not negated, and only the address
is changed before the next access is executed. When 8-bit ROM is connected, the number of
consecutive accesses can be set as 4, 8, or 16 by bits A0BST (1 to 0), A5BST (1 to 0), or A6BST
(1 to 0). When 16-bit ROM is connected, 4 or 8 can be set in the same way. When 32-bit ROM is
connected, only 4 can be set.
WAIT
pin sampling is performed in the first access if one or more wait states are set, and is
always performed in the second and subsequent accesses.
The second and subsequent access cycles also comprise two cycles when a burst ROM setting is
made and the wait specification is 0. The timing in this case is shown in figure 8.29.
However, the
WAIT
signal is ignored in the following cases:
•
In 16-byte DMA transfer or dual addressing mode, or when writing data to the external address
area
•
In 16-byte DMA transfer or single addressing mode, or when transferring data from an
external device with DACK to the external bus area
•
When accessing cache for write back
Содержание SH7706 Series
Страница 8: ...Rev 5 00 May 29 2006 page viii of xlviii ...
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 ...