HD6412240 RENESAS [Renesas Technology Corp], HD6412240 Datasheet - Page 178

• Manufacturer Part Number: HD6412240
• Description: Renesas 16-Bit Single-Chip Microcomputer H8S Family / H8S/2200 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

Section 6 Bus Controller
6.2.2
ASTCR is an 8-bit readable/writable register that designates each area as either a 2-state access
space or a 3-state access space.
ASTCR sets the number of access states for the external memory space. The number of access
states for on-chip memory and internal I/O registers is fixed regardless of the settings in ASTCR.
In normal mode, the settings of bits AST7 to AST1 have no effect on operation.
ASTCR is initialized to H'FF by a power-on reset and in hardware standby mode. It is not
initialized by a manual reset or in software standby mode.
Bits 7 to 0—Area 7 to 0 Access State Control (AST7 to AST0): These bits select whether the
corresponding area is to be designated as a 2-state access space or a 3-state access space. In
normal mode, only part of area 0 is enabled, and the AST0 bit selects whether external space is to
be designated for 2-state access or 3-state access.
Wait state insertion is enabled or disabled at the same time.
Bit n
ASTn
0
1
Note: n = 7 to 0
Rev.3.00 Mar. 26, 2007 Page 136 of 772
REJ09B0355-0300
Bit
Initial value
R/W
Access State Control Register (ASTCR)
Description
Area n is designated for 2-state access
Wait state insertion in area n external space is disabled
Area n is designated for 3-state access
Wait state insertion in area n external space is enabled
:
:
:
AST7
R/W
7
1
AST6
R/W
6
1
AST5
R/W
5
1
AST4
R/W
4
1
AST3
R/W
3
1
AST2
R/W
2
1
AST1
R/W
1
1
(Initial value)
AST0
R/W
0
1