SH7760 Datasheet, PDF (302/1345 Pages) Renesas Technology Corp – SuperHTM RISC engine

10.5.4 Bus Control Register 4 (BCR4)
BCR4 is a 32-bit readable/writable register that enables asynchronous input for pins corresponding
to individual bits. When asynchronous input is set (ASYNCn = 1), the sampling timing is one
cycle earlier than when synchronous input is set (ASYNCn = 0). With the synchronous input
setting, ensure that setup and hold times are observed.
The timings shown in this section and section 33, Electrical Characteristics, are all for the case
where synchronous input is set (ASYNCn = 0).
Bit: 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Initial value: 0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
R/W: R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
Bit: 15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
-
-
-
-
-
-
-
-
-
ASYN ASYN ASYN ASYN ASYN ASYN ASYN
C6 C5 C4 C3 C2 C1 C0
Initial value: 0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
R/W: R
R
R
R
R
R
R
R
R R/W R/W R/W R/W R/W R/W R/W
Bit
Initial
Bit
Name Value R/W
31 to 7 
All 0
R
6
ASYNC6 0
R/W
5
ASYNC5 0
R/W
4
ASYNC4 0
R/W
Description
Reserved
These bits are always read as 0. The write value should
always be 0.
Asynchronous Input 6
0: The DREQ3 pin can be used for synchronous input
with the CKIO signal.
1: The DREQ3 pin can be used for asynchronous input
with the CKIO signal.
Asynchronous Input 5
0: The DREQ2 pin can be used for synchronous input
with the CKIO signal.
1: The DREQ2 pin can be used for asynchronous input
with the CKIO signal.
Asynchronous Input 4
0: The IOIS16 pin can be used for synchronous input
with the CKIO signal.
1: The IOIS16 pin can be used for asynchronous input
with the CKIO signal.
Rev. 1.0, 02/03, page 252 of 1294