p2125vps20 Renesas Electronics Corporation., p2125vps20 Datasheet - Page 156

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

Section 6 Bus Controller (BSC)
6.5.4
When accessing the external address space, this LSI can extend the bus cycle by inserting one or
more wait states (T
wait insertion using the WAIT pin, and the combination of program wait and the WAIT pin.
(1)
A specified number of wait states T
state when accessing the external address space always according to the settings of the WC1 and
WC0 bits in WSCR.
(2)
A specified number of wait states T
state when accessing the external address space always according to the settings of the WC1 and
WC0 bits. If the WAIT pin is low at the falling edge of φ in the last T
is inserted. If the WAIT pin is held low, T
This is useful when inserting four or more T
be inserted for each external device.
(3)
A specified number of wait states T
state when accessing the external address space according to the settings of the WC1 and WC0
bits if the WAIT pin is low at the falling edge of φ in the last T
held low, T
This function enables the low-speed memory interface only by inputting the chip select signal to
the WAIT pin.
Figure 6.7 shows an example of wait state insertion timing in pin wait mode.
The settings after a reset are: 3-state access, 3 program wait insertion, and WAIT pin input
disabled.
Rev. 1.00 Sep. 21, 2006 Page 118 of 658
REJ09B0310-0100
Program Wait Mode
Pin Wait Mode
Pin Auto-Wait Mode
Wait Control
W
states can be inserted only up to the specified number of states.
W
). There are three ways of inserting wait states: Program wait insertion, pin
W
W
W
can be inserted automatically between the T
can be inserted automatically between the T
can be inserted automatically between the T
W
states are inserted until it goes high.
W
states, or when changing the number of T
2
state. Even if the WAIT pin is
2
or T
W
state, another T
2
2
2
state and T
state and T
state and T
W
states to
W
3
3
3
state