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Section 6 Bus Controller
6.7.4
Wait Control
With memory card interface, there are two ways of inserting wait states: Program wait insertion
and pin wait insertion using the CPWAIT pin.
Program Wait Mode: A specified number of wait states T
and T
state when accessing the CF expansion area according to the settings in the WC22, WC21,
3
and WC20 bits in WSCR2.
Pin Wait Mode: A specified number of wait states T
state when accessing the CF expansion area according to the settings in the WC22, WC21, and
WC20 bits. If the CPWAIT pin is low at the falling edge of φ in the last T
state is inserted. If the CPWAIT pin is held low, T
state insertion by the CPWAIT pin is not performed unless program wait mode
however, that T
W
is specified.
Figure 6.19 shows an example of wait state insertion timing.
φ
CPWAIT
Address bus
CPCS1, CPCS2
CPOE
Read
D15 to D0
CPWE
Write
D15 to D0
Figure 6.19 Access Timing Example in Memory Card Mode (Wait State Insertion by
Rev. 3.00 Jan 25, 2006 page 140 of 872
REJ09B0286-0300
By program wait
T
T
1
W
Program Wait and CPWAIT
can be inserted between the T
W
can be inserted between the T
W
states are inserted until it goes high. Note,
W
By CPWAIT pin
T
T
W
W
Valid
CPWAIT Pin)
CPWAIT
CPWAIT
2
state and T
2
or T
state, another T
2
W
T
T
2
3
Valid
state
3
W
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