HD6412320 RENESAS [Renesas Technology Corp], HD6412320 Datasheet - Page 218

• Manufacturer Part Number: HD6412320
• Description: Renesas 16-Bit Single-Chip Microcomputer H8S Family H8S-2300 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

Section 6 Bus Controller
6.5.8
Wait Control
There are two ways of inserting wait states in a DRAM access cycle: program wait insertion and
pin wait insertion using the WAIT pin.
Program Wait Insertion: When the bit in ASTCR corresponding to an area designated as DRAM
space is set to 1, from 0 to 3 wait states can be inserted automatically between the T
state and T
c1
c2
state, according to the settings of WCRH and WCRL.
Pin Wait Insertion: When the WAITE bit in BCRH is set to 1, wait input by means of the WAIT
pin is enabled regardless of the setting of the AST bit in ASTCR. When DRAM space is accessed
in this state, a program wait is first inserted. If the WAIT pin is low at the falling edge of φ in the
state is inserted. If the WAIT pin is held low, T
last T
or T
state, another T
states are inserted
c1
w
w
w
until it goes high.
Figure 6.17 shows an example of wait state insertion timing.
Rev.6.00 Sep. 27, 2007 Page 188 of 1268
REJ09B0220-0600