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Read and Write Strobe Mode #4
Read and Write Strobe Mode #4 uses the I/O direction line as a Strobe
pulse to indicate writing operations. The PCTL line is used to indicate
Read operations. It is thus similar to the R/W and Strobe Mode #3 except
separate control lines are used for the Strobe pulses and there is no I/O
direction line.
DATA LINES
W rite O peration
IO DIRECTION (WR)
The IO Direction line is used to indicate that the data is valid on the data bus lines.
IO Direction is used to trigger the receiving device.
DATA LINES
R ea d O p era tion
PCTL (RD) LINE
As in Mode #3, the PCTL (RD) line is used to indicate to the sending
device that the 3499A/B/C has latched (read) the data.
Chapter 4 Features and Functions
DATA VALID
t1
t2
40 s
20 s
DATA VALID
t2
t1
100 s
20 s
Digital I/O Operation
4
t 1 = T im e fr om d a t a
v a lid to w r ite
S tr ob e
(4 0 s m in im u m )
t 2 = S tro b e p u lse w id th
(2 0 s m in im u m )
t1 = T im e from o u tp u t
d isa b le to rea d
S tr ob e (1 0 0
s
m in im u m )
t 2 = S tr ob e p u lse w id th
(2 0 s m in im u m )
89
4
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