p2125vps20 Renesas Electronics Corporation., p2125vps20 Datasheet - Page 150

• Manufacturer Part Number: p2125vps20
• Description: 16-bit Single-chip Microcomputer H8s Family / H8s/2100 Series
• Manufacturer: Renesas Electronics Corporation.

Section 6 Bus Controller (BSC)
6.4.4
The LSI can output I/O select signals (IOS); the signal is driven low when the corresponding
external address space is accessed. Figure 6.2 shows an example of IOS signal output timing.
Enabling or disabling IOS signal output is performed by the IOSE bit in SYSCR. In extended
mode, the IOS pin functions as an AS pin by a reset. To use this pin as an IOS pin, set the IOSE
bit to 1. For details, refer to section 8, I/O Ports.
The address ranges of the IOS signal output can be specified by the IOS1 and IOS0 bits in BCR,
as shown in table 6.3.
Table 6.3
Rev. 1.00 Sep. 21, 2006 Page 112 of 658
REJ09B0310-0100
IOS1
0
1
I/O Select Signals
Address Range for IOS Signal Output
IOS0
0
1
0
1
Address bus
φ
IOS
Figure 6.2 IOS Signal Output Timing
IOS Signal Output Range
H'(FF)F000 to H'(FF)F03F
H'(FF)F000 to H'(FF)F0FF
H'(FF)F000 to H'(FF)F3FF
H'(FF)F000 to H'(FF)F7FF
T
1
External addresses selected by IOS
Bus cycle
T
2
T
3
(Initial value)