Synchronous Handshake Mode - Agilent Technologies 34950A User Manual

Handshaking

Synchronous Handshake Mode

In the synchronous handshake mode, a strobe or clock signal is used to
transfer data to or from an external device. The strobe line (H1) is an
output and is pulsed once for each transfer.
Synchronous Unbuffered Inputs
For synchronous handshake unbuffered inputs the H0 line indicates the
direction of the transfer. This line is set high to indicate an input
operation. The H0 line will remain in the high state until the 34950A
direction is changed. The H1 line is the strobe output line. The H2 line is
not used and is set to high impedance.
The timing of the input operation is controlled by the T parameter
CYCLE
set using the command. This setting
CONFigure:DIGital:HANDshake:RATE
affects strobe width, memory clock rate, as well as the setup and hold
times. Alternatively, the reciprocal form of the command
can be used to specify the speed in
CONFigure:DIGital:HANDshake:CTIMe
terms of time instead of a rate. T begins when the 34950A executes
CYCLE
one of the input commands.
The timing should be set such that the device sending the data ensures
the data lines are valid prior to T time. The trailing edge of the
SETUP
strobe line indicates the 34950A will latch the data within the T time.
HOLD
µ
T is 90 ns and T is 0 ns. Since T = 0 s, the sending device
SETUP HOLD HOLD
can use the trailing edge of the strobe to initiate a change in the data
lines.
A synchronous unbuffered input is shown in the diagram below
(default handshake line polarity).
H0 (Direction)
T
CYC LE
T / 2 T / 2
CYC LE CYC LE
H1 (Strobe)
T T
SETUP HOLD
Data In
Don't-Care Valid Don't-Care
For example, the following SCPI commands set a 34950A in slot 5 to have
a 16- bit input using synchronous handshake. Two data inputs are then
performed and the strobe line is pulsed for each query. The I/O direction
line is set high following the first query and
SENSe:DIGital:DATA:WORD?
remains high until the digital channel is reset or reconfigured.
CONF:DIG:WIDT WORD, (@5101)
CONF:DIG:DIR INP, (@5101)
CONF:DIG:HAND SYNC, (@5101)
SENS:DIG:DATA:WORD? (@5101)
SENS:DIG:DATA:WORD? (@5101)
Agilent 34950A 64-Bit Digital I/O and Counter Module User's Guide 9