National Instruments 653 Series User Manual page 84

ACK
REQ
Input Data Valid
(REQ-edge
Latching)
Input Data Valid
(REQ-edge
Latching Disabled)
Parameter
Input Parameters
t
REQ pulse width
rr*
t
REQ inactive duration
r*r
t
ACK to next REQ
ar
t
Input data setup to REQ active
dir(1)
(with REQ-edge latching)
t
Input data hold from REQ active
rdi
(with REQ-edge latching)
t
Input data setup to REQ
dir(2)
(with REQ-edge latching disabled)
t
Input data hold from ACK
adi
(with REQ-edge latching disabled)
Output Parameters
t
ACK pulse width
aa*
t
REQ inactive to ACK inactive
r*a*
All timing values are in nanoseconds.
With REQ-edge latching enabled (default), the REQ edge determines when data is
Note
latched. Input data valid must be held before an active-going REQ edge for a minimum of
t ns. With REQ edge disabled, it must be held t
rdi
edge occurs.
© National Instruments Corporation
t
aa*
t
r*a*
t
ar
t
r*r
t t
dir(1) rdi
t
dir(2)
Description
Figure 3-28. Leading-Edge Input Timing Diagram
3-29
Chapter 3
t
rr*
ACK and REQ are shown as active high.
Minimum
75
75
0
0
10
0
0
125
150
after the next active-going ACK signal
adi
Timing Diagrams
t
adi
Maximum
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NI 653X User Manual