SH7751 Datasheet, PDF (498/1224 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer

13. Bus State Controller (BSC)
13.3.2 Areas
Area 0: For area 0, external address bits 28 to 26 are 000.
SRAM, MPX, and burst ROM can be set for this area.
A bus width of 8, 16, or 32 bits can be selected in a power-on reset by means of external pins
MD4 and MD3. For details, see Memory Bus Width in section 13.1.5, Overview of Areas.
When area 0 is accessed, the CS0 signal is asserted. In addition, the RD signal, which can be used
as OE, and write control signals WE0 to WE3, are asserted.
As regards the number of bus cycles, from 0 to 15 waits can be selected with bits A0W2 to A0W0
in the WCR2 register. In addition, any number of waits can be inserted in each bus cycle by means
of the external wait pin (RDY).
When the burst ROM interface is used, the number of burst cycle transfer states is selected in the
range 2 to 9 according to the number of waits.
The read/write strobe signal address and the CS setup/hold time can be set, respectively, to 0 or 1
and to 0 to 3 cycles using the A0S0, A0H1, and A0H0 bits in the WCR3 register.
Area 1: For area 1, external address bits 28 to 26 are 001.
SRAM, MPX, and byte control SRAM can be set for this area.
A bus width of 8, 16, or 32 bits can be selected with bits A1SZ1 and A1SZ0 in the BCR2 register.
When MPX interface is set, a bus width of 32 bit should be selected with bits A1SZ1 and A1SZ0
in the BCR2 register. When byte control SRAM interface is set, select a bus width of 16 or 32 bits.
When area 1 is accessed, the CS1 signal is asserted. In addition, the RD signal, which can be used
as OE, and write control signals WE0 to WE3, are asserted.
As regards the number of bus cycles, from 0 to 15 waits can be selected with bits A1W2 to A1W0
in the WCR2 register. In addition, any number of waits can be inserted in each bus cycle by means
of the external wait pin (RDY).
The read/write strobe signal address and CS setup and hold times can be set within a range of 0–1
and 0–3 cycles, respectively, by means of bit A1S0 and bits A1H1 and A1H0 in the WCR3
register.
Rev.4.00 Oct. 10, 2008 Page 400 of 1122
REJ09B0370-0400