Handshaking
Agilent 34950A 64-Bit Digital I/O and Counter Module User’s Guide
11
Synchronous Buffered Inputs
You can use synchronous mode handshake with buffered (memory) input
operations. (Buffered operations are described in more detail beginning on
page 14
.) For buffered input operations, the H0 line acts as a start/stop
line. This line will be set high when the memory input command is
executed and will return low when the memory input operation has
completed. The H1 line is not used and is set to high impedance.
An external strobe input on the H2 line controls the pace of memory
transfers. The sending device must ensure the data is valid before the
T
SETUP
and stays valid until after T
HOLD
. T
SETUP
is 46 ns and T
HOLD
is
10 ns.
A synchronous buffered input using an external clock is shown in the
diagram below (default handshake line polarity).
For example, the following SCPI commands set a 34950A in slot 5 to have
an 8- bit input using synchronous handshake with an external strobe input.
The number of bytes to read into memory is set to infinite (continuous
reading into memory until the memory is stopped). The memory is
enabled and then triggered. The start/stop line is set high following the
first byte handshake and remains high until the last byte is captured.
CONF:DIG:WIDT BYTE, (@5101)
CONF:DIG:DIR INP, (@5101)
CONF:DIG:HAND SYNC, (@5101)
SENS:DIG:MEM:SAMP:COUN 0, (@5101)
SENS:DIG:MEM:ENAB ON, (@5101)
SENS:DIG:MEM:STAR (@5101)
H0 (Start
/
Sto
p
)
H
2
(Strobe In)
Data In
Valid
Don't-Care
T
SETUP
T
HOLD
T
CYCLE
> 100
n
s
T
SETUP
T
HOLD
Valid
(
La
s
t C
yc
le
)
Don't-Care
Don't-Care
Don't-Care
Valid
> 50
n
s
