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Section 12 Bus State Controller (BSC)
Rev. 4.00 Sep. 14, 2005 Page 377 of 982
REJ09B0023-0400
CKIO
A25 to A0
RD
D15 to D0
DACKn
*
Note:
*
The waveform for
DACKn
when active low is specified.
WAIT
CSn
T1
Tw
Tw
TB2
Twb
TB2
Twb
TB2
Twb T2
RD/
WR
BS
Figure 12.36 Burst ROM Access Timing (Clock Asynchronous)
(Bus Width = 32 Bits, 16-Byte Transfer (Number of Burst 4), Wait Cycles Inserted in First
Access = 2, Wait Cycles Inserted in Second and Subsequent Accesses = 1)
12.5.8
Byte-Selection SRAM Interface
The byte-selection SRAM interface is for access to an SRAM which has a byte-selection pin
(
WEn
). This interface has 16-bit data pins and accesses SRAMs having upper and lower byte
selection pins, such as UB and LB.
When the BAS bit in the CSnWCR register is cleared to 0 (initial value), the write access timing
of the byte-selection SRAM interface is the same as that for the normal space interface. While in
read access of a byte-selection SRAM interface, the byte-selection signal is output from the
WEn
pin, which is different from that for the normal space interface. The basic access timing is shown
in figure 12.37. In write access, data is written to the memory according to the timing of the byte-
selection pin (
WEn
). For details, please refer to the Data Sheet for the corresponding memory.
If the BAS bit in the CSnWCR register is set to 1, the
WEn
pin and RD/
WR
pin timings change.
Figure 12.38 shows the basic access timing. In write access, data is written to the memory
according to the timing of the write enable pin (RD/
WR
). The data hold timing from RD/
WR
negation to data write must be acquired by setting the HW1 and HW0 bits in the CSnWCR
register. Figure 12.39 shows the access timing when a software wait is specified.
Содержание HD6417641
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Страница 11: ...Rev 4 00 Sep 14 2005 Page xi of l USB Universal serial bus WDT Watch dog timer...
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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...
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Страница 1036: ...SH7641 Hardware Manual...