12
Agilent 34950A 64-Bit Digital I/O and Counter Module User’s Guide
Handshaking
Synchronous Buffered Outputs
You can use synchronous mode handshake with buffered (memory) output
operations. (Buffered operations are described in more detail beginning on
page 14
.) For buffered output operations, the H0 line acts as a start/stop
line. This line will be set high when the memory output command is
executed by the 34950A and will return low when the memory output
operation has completed.
Synchronous memory output operations can be paced using either the
internal
strobe or an
external
strobe.
When using the
internal
strobe, the H1 line is the strobe output line.
The timing of the output operation when using the default
INTernal
clock
is controlled by the
CONFigure:DIGital:HANDshake:RATE
command.
This setting affects strobe width, memory clock rate, as well as the setup
and hold times. Alternatively, the reciprocal form of the command
CONFigure:DIGital:HANDshake:CTIMe
can be used to specify the speed in
terms of time instead of a rate. The timing should be set such that the
device receiving the data can latch the data lines during the T
CYCLE
time.
The receiving device should detect the leading edge of the strobe line, wait
for the 34950A to set the data (T
PD
) and then latch the data. Latching the
data on the trailing edge of the strobe is recommended, however, you can
the data following T
PD
. T
PD
ranges from - 23 to 23 ns.
A synchronous buffered output using the internal clock is shown in the
diagram below (default handshake line polarity).
H0 (Start
/
Sto
p
)
H1 (Strobe
Ou
t)
Data
Ou
t
Valid
T
CYC LE
(
La
s
t C
yc
le
)
I
n
v
alid
T
PD
T
PD
T
PD
T
CYC LE
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