SH7751 Datasheet, PDF (459/1224 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer

13. Bus State Controller (BSC)
13.2.4 Bus Control Register 4 (BCR4) (SH7751R Only)
Bus control register 4 (BCR4) is a register that enables asynchronous input for pins corresponding
to individual bits.
The BCR4 register is a 32-bit readable/writable register. It is initialized to H'00000000 by a
power-on reset, but is not initialized by a manual reset or in standby mode.
When asynchronous input is set (ASYNCn = 1), the sampling timing is one cycle earlier than
when synchronous input is set (ASYNCn = 0)* (see figure 13.4)
The timings shown in this section and section 23, Electrical Characteristics, are all for the case
where synchronous input is set (ASYNCn = 0).
Note: * With the synchronous input setting, ensure that setup and hold times are observed.
Bit: 31
30
29
28
27
26
25
24
—
—
—
—
—
—
—
—
Initial value:
0
0
0
0
0
0
0
0
R/W: R
R
R
R
R
R
R
R
Bit: 23
22
21
20
19
18
17
16
—
—
—
—
—
—
—
—
Initial value:
0
0
0
0
0
0
0
0
R/W: R
R
R
R
R
R
R
R
Bit: 15
14
13
12
11
10
9
8
—
—
—
—
—
—
—
—
Initial value:
0
0
0
0
0
0
0
0
R/W: R
R
R
R
R
R
R
R
Bit:
7
6
5
4
3
2
1
0
—
—
— ASYNC4 ASYNC3 ASYNC2 ASYNC1 ASYNC0
Initial value:
0
0
0
0
0
0
0
0
R/W: R
R
R
R/W
R/W
R/W
R/W
R/W
Bits 31 to 5—Reserved: These bits are always read as 0, and the write value should always be 0.
Rev.4.00 Oct. 10, 2008 Page 361 of 1122
REJ09B0370-0400