Datasheet

Section 6 Bus Controller
Rev. 4.00 Jun 06, 2006 page 142 of 1004
REJ09B0301-0400
Bit 7—RAM Select (RAMS)/Bit 6—RAM Area Setting (RAM0): These are reserved bits.
Always write 0 when writing to these bits in the A-mask version.
Bit 5—Bus Width Control (ABW): Specifies whether the external memory space is 8-bit access
space or 16-bit access space.
However, a 16-bit access space cannot be specified for these group, and therefore 0 should not be
written to this bit.
Bit 5
ABW Description
0 External memory space is designated as 16-bit access space (A 16-bit access space
cannot be specified for these group)
1 External memory space is designated as 8-bit access space (Initial value)
Bit 4—Access State Control (AST): Specifies whether the external memory space is 2-state
access space or 3-state access space, and simultaneously enables or disables wait state insertion.
Bit 4
AST Description
0 External memory space is designated as 2-state access space
Wait state insertion in external memory space accesses is disabled
1 External memory space is designated as 3-state access space (Initial value)
Wait state insertion in external memory space accesses is enabled
Bits 3 and 2—Wait Mode Select 1 and 0 (WMS1, WMS0): These bits select the wait mode
when external memory space is accessed while the AST bit is set to 1.
Bit 3 Bit 2
WMS1 WMS0 Description
0 0 Program wait mode (Initial value)
1 Wait-disabled mode
1 0 Pin wait mode
1 Pin auto-wait mode