h8s-2158 Renesas Electronics Corporation., h8s-2158 Datasheet - Page 185

• Manufacturer Part Number: h8s-2158
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2100 Series
• Manufacturer: Renesas Electronics Corporation.

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/CPWAIT pin, and the combination of program wait and the
WAIT/CPWAIT pin.
Program Wait Mode: A specified number of wait states T
between the T
the settings of the WC1 and WC0 bits in WSCR (the WC11 and WC10 bits in WSCR2 for the
256-kbyte expansion area, and the WC21 and WC20 bits in WSCR2 for the CP expansion area).
Pin Wait Mode: A specified number of wait states T
T
the WC1 and WC0 bits (the WC21 and WC20 bits for the CP expansion area). If the
WAIT/CPWAIT pin is low at the falling edge of in the last T
inserted. If the WAIT/CPWAIT pin is held low, T
This is useful when inserting four or more T
be inserted for each external device.
Pin Auto-Wait Mode: A specified number of wait states T
between the T
settings of the WC1 and WC0 bits (the WC21 and WC20 bits for the CP expansion area) if the
WAIT/CPWAIT pin is low at the falling edge of in the last T
pin is held low, T
This function enables the low-speed memory interface only by inputting the chip select signal to
the WAIT/CPWAIT pin.
Figure 6.13 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/CPWAIT pin
input disabled.
2
state and T
Wait Control
3
2
2
state when accessing the external address space always according to the settings of
state and T
state and T
W
W
states can be inserted only up to the specified number of states.
). There are three ways of inserting wait states: Program wait insertion, pin
3
3
state when accessing the external address space always according to
state when accessing the external address space according to the
W
states, or when changing the number of T
W
states are inserted until it goes high.
W
can be inserted automatically between the
Rev. 3.00 Jan 25, 2006 page 133 of 872
W
W
can be inserted automatically
can be inserted automatically
2
2
or T
state. Even if the WAIT/CPWAIT
W
state, another T
Section 6 Bus Controller
REJ09B0286-0300
W
W
state is
states to