136
6.7
Register and Pin Input Timing
6.7.1
Register Write Timing
ABWCR, ASTCR, WCRH, and WCRL Write Timing: Data written to ABWCR, ASTCR,
WCRH, and WCRL takes effect starting from the next bus cycle. Figure 6.22 shows the timing
when an instruction fetched from area 0 changes area 0 from three-state access to two-state access.
φ
T
1
T
2
T
3
T
1
T
2
T
3
T
1
T
2
Address bus
3-state access to area 0
2-state access to area 0
ASTCR address
Figure 6.22 ASTCR Write Timing
DDR and CSCR Write Timing: Data written to DDR or CSCR for the port corresponding to the
CS
n pin to switch between
CS
n output and generic input takes effect starting from the T
3
state of
the DDR write cycle. Figure 6.23 shows the timing when the
CS
1
pin is changed from generic
input to
CS
1
output.
φ
T
1
T
2
T
3
CS
1
Address bus
High-impedance
P8DDR address
Figure 6.23 DDR Write Timing
BRCR Write Timing: Data written to BRCR to switch between A
23
, A
22
, A
21
, or A
20
output and
generic input or output takes effect starting from the T
3
state of the BRCR write cycle. Figure
6.24 shows the timing when a pin is changed from generic input to A
23
, A
22
, A
21
, or A
20
output.
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