H8S2158 Datasheet, PDF (192/927 Pages) Renesas Technology Corp – Renesas 16-Bit Single-Chip Microcomputer H8S Family/H8S/2100 Series

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_W can be inserted between the T₂ state
and T₃ state when accessing the CF expansion area according to the settings in the WC22, WC21,
and WC20 bits in WSCR2.
Pin Wait Mode: A specified number of wait states T_W can be inserted between the T₂ state and T₃
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 T₂ or T_W state, another T_W
state is inserted. If the CPWAIT pin is held low, T_W states are inserted until it goes high. Note,
however, that T_W state insertion by the CPWAIT pin is not performed unless program wait mode
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
By program wait
By CPWAIT pin
T₁
T_W
T_W
T_W
Valid
T₂
T₃
Valid
Figure 6.19 Access Timing Example in Memory Card Mode (Wait State Insertion by
Program Wait and CPWAIT Pin)
Rev. 3.00 Jan 25, 2006 page 140 of 872
REJ09B0286-0300