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Section 12 Bus State Controller (BSC)
Rev. 4.00 Sep. 14, 2005 Page 376 of 982
REJ09B0023-0400
12.5.7
Burst ROM (Clock Asynchronous) Interface
The burst ROM (clock asynchronous) interface is used to access a memory with a high-speed read
function using a method of address switching called the burst mode or page mode. In a burst ROM
(clock asynchronous) interface, basically the same access as the normal space is performed, but
the 2nd and subsequent accesses are performed only by changing the address, without negating the
RD
signal at the end of the 1st cycle. In the 2nd and subsequent accesses, addresses are changed at
the falling edge of the CKIO.
For the 1st access cycle, the number of wait cycles specified by the W3 to W0 bits in the
CSnWCR register is inserted. For the 2nd and subsequent access cycles, the number of wait cycles
specified by the W1 to W0 bits in the CSnWCR register is inserted.
In the access to the burst ROM (clock asynchronous), the
BS
signal is asserted only to the first
access cycle. An external wait input is valid only to the first access cycle. In the single access or
write access that do not perform the burst operation in the page flash ROM interface, access
timing is same as a normal space. Table 12.17 lists a relationship between bus width, access size,
and the number of bursts. Figure 12.36 shows a timing chart.
Table 12.17 Relationship between Bus Width, Access Size, and Number of Bursts
Bus Width
CSnWCR. BEN Bit
Access Size
Number of Bursts Number of Accesses
8 bits
Not affected
8 bits
1
1
Not affected
16 bits
2
1
Not affected
32 bits
4
1
0
16
bytes
16
1
1
4
4
16 bits
Not affected
8 bits
1
1
Not affected
16 bits
1
1
Not affected
32 bits
2
1
0
16
bytes
8
1
1
2
4
32 bits
Not affected
8 bits
1
1
Not affected
16 bits
1
1
Not affected
32 bits
1
1
Not affected
16 bytes
4
1
Summary of Contents for HD6417641
Page 2: ...Rev 4 00 Sep 14 2005 Page ii of l...
Page 7: ...Rev 4 00 Sep 14 2005 Page vii of l...
Page 11: ...Rev 4 00 Sep 14 2005 Page xi of l USB Universal serial bus WDT Watch dog timer...
Page 12: ...Rev 4 00 Sep 14 2005 Page xii of l...
Page 28: ...Rev 4 00 Sep 14 2005 Page xxviii of l...
Page 204: ...Section 4 Clock Pulse Generator CPG Rev 4 00 Sep 14 2005 Page 154 of 982 REJ09B0023 0400...
Page 212: ...Section 5 Watchdog Timer WDT Rev 4 00 Sep 14 2005 Page 162 of 982 REJ09B0023 0400...
Page 228: ...Section 6 Power Down Modes Rev 4 00 Sep 14 2005 Page 178 of 982 REJ09B0023 0400...
Page 246: ...Section 8 X Y Memory Rev 4 00 Sep 14 2005 Page 196 of 982 REJ09B0023 0400...
Page 318: ...Section 11 User Break Controller UBC Rev 4 00 Sep 14 2005 Page 268 of 982 REJ09B0023 0400...
Page 454: ...Section 12 Bus State Controller BSC Rev 4 00 Sep 14 2005 Page 404 of 982 REJ09B0023 0400...
Page 504: ...Section 14 U Memory Rev 4 00 Sep 14 2005 Page 454 of 982 REJ09B0023 0400...
Page 566: ...Section 17 Compare Match Timer CMT Rev 4 00 Sep 14 2005 Page 516 of 982 REJ09B0023 0400...
Page 868: ...Section 21 A D Converter Rev 4 00 Sep 14 2005 Page 818 of 982 REJ09B0023 0400...
Page 914: ...Section 23 I O Ports Rev 4 00 Sep 14 2005 Page 864 of 982 REJ09B0023 0400...
Page 956: ...Section 24 List of Registers Rev 4 00 Sep 14 2005 Page 906 of 982 REJ09B0023 0400...
Page 1016: ...Section 25 Electrical Characteristics Rev 4 00 Sep 14 2005 Page 966 of 982 REJ09B0023 0400...
Page 1024: ...Appendix Rev 4 00 Sep 14 2005 Page 974 of 982 REJ09B0023 0400...
Page 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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