Figure 12. Read-to-Write-to-Read (OE Controlled)
Figure 13. Read with Address Counter Advance
t
SA
t
HA
t
CH2
t
CL2
t
CYC2
CLK
ADDRESS
A
n
COUNTER HOLD
READ WITH COUNTER
t
SAD
t
HAD
t
SCN
t
HCN
t
SAD
t
HAD
t
SCN
t
HCN
Q
x–1
Q
x
Q
n
Q
n+1
Q
n+2
Q
n+3
t
DC
t
CD2
READ WITH COUNTER
READ
EXTERNAL
ADDRESS
ADS
CNTEN
DATA
OUT
Notes
37. Addresses do not have to be accessed sequentially since ADS
= CNTEN = V
IL
with CNT/MSK = V
IH
constantly loads the address on the rising edge of the CLK.
Numbers are for reference only
38. Output state (HIGH, LOW, or high-impedance) is determined by the previous cycle control signals.
39. CE
0
= OE = B0 – B3 = LOW; CE
1
= R/W = CNTRST = MRST = HIGH.
40. CE
0
= B0 – B3 = R/W = LOW; CE
1
= CNTRST = MRST = CNT/MSK = HIGH. When R/W first switches low, since OE = LOW, the Write operation cannot be completed
(labelled as no operation). One clock cycle is required to three-state the I/O for the Write operation on the next rising edge of CLK.
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