Section 11 Local Bus State Controller (LBSC)
Rev.1.00 Dec. 13, 2005 Page 389 of 1286
REJ09B0158-0100
11.5.7 Byte
Control SRAM Interface
The byte control SRAM interface is a memory interface that outputs a byte-select strobe (
WE
) in
both read and write bus cycles. This interface has 16-bit data pins and can be connected to SRAM
having an upper byte select strobe and lower select strobe functions, such as UB and LB.
Areas 1 and 4 can be specified as a byte control SRAM interface. However, when these areas are
set to the MPX interface, the MPX interface has priority.
The write timing for the byte control SRAM interface is identical to that of a normal SRAM
interface.
In read operations, on the other hand, the
WE
pin timing is different. In a read access, only the
WE
signal for the byte being read is asserted. Assertion is synchronized with the falling edge of the
CLKOUT clock in the same way as for the
WE
signal, while negation is synchronized with the
rising edge of the CLKOUT clock in the same way as for the
RD
signal.
In 32-byte transfer, a total of 32 bytes are transferred continuously according to the set bus width.
The first access is performed on the data for which there was an access request, and the remaining
accesses are performed in wraparound method according to the set bus width. The bus is not
released during this transfer.
Figure 11.30 shows an example of a byte control SRAM connection, and figures 11.31 to 11.33
show examples of byte-control SRAM read cycles.
A17 to A2
CSn
RD
R/
W
SH7780
64 K × 16-bit
SRAM
D15 to D0
WE1
WE0
A15 to A0
CS
OE
WE
I/O15 to I/O0
UB
LB
A15 to A0
CS
OE
WE
I/O15 to I/O0
UB
LB
D31 to D16
WE3
WE2
Figure 11.30 Example of 32-Bit Data-Width Byte-Control SRAM
Summary of Contents for SH7780 Series
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Page 122: ...Section 3 Instruction Set Rev 1 00 Dec 13 2005 Page 72 of 1286 REJ09B0158 0100 ...
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Page 196: ...Section 6 Floating Point Unit FPU Rev 1 00 Dec 13 2005 Page 146 of 1286 REJ09B0158 0100 ...
Page 292: ...Section 9 L Memory Rev 1 00 Dec 13 2005 Page 242 of 1286 REJ09B0158 0100 ...
Page 492: ...Section 12 DDR SDRAM Interface DDRIF Rev 1 00 Dec 13 2005 Page 442 of 1286 REJ09B0158 0100 ...
Page 674: ...Section 15 Clock Pulse Generator CPG Rev 1 00 Dec 13 2005 Page 624 of 1286 REJ09B0158 0100 ...
Page 692: ...Section 16 Watchdog Timer and Reset Rev 1 00 Dec 13 2005 Page 642 of 1286 REJ09B0158 0100 ...
Page 726: ...Section 18 Timer Unit TMU Rev 1 00 Dec 13 2005 Page 676 of 1286 REJ09B0158 0100 ...
Page 1032: ...Section 25 Audio Codec Interface HAC Rev 1 00 Dec 13 2005 Page 982 of 1286 REJ09B0158 0100 ...
Page 1150: ...Section 28 General Purpose I O GPIO Rev 1 00 Dec 13 2005 Page 1100 of 1286 REJ09B0158 0100 ...
Page 1184: ...Section 29 User Break Controller UBC Rev 1 00 Dec 13 2005 Page 1134 of 1286 REJ09B0158 0100 ...
Page 1266: ...Section 31 Electrical Characteristics Rev 1 00 Dec 13 2005 Page 1216 of 1286 REJ09B0158 0100 ...
Page 1328: ...Appendix Rev 1 00 Dec 13 2005 Page 1278 of 1286 REJ09B0158 0100 ...
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