National Instruments 653X User Manual page 68

ACK
REQ
Data In Valid
Data Out Valid
Parameter
Input Parameters
t
REQ low duration
r*r
t
REQ high duration
rr*
t
ACK falling edge to REQ rising edge
a*r
t
Input data valid to REQ rising edge
dir
t
REQ rising edge to input data invalid
rdi
Output Parameters
t
ACK high duration
aa*
t
REQ falling edge to ACK rising edge
r*a
t
Output data valid to ACK falling edge
doa*
t
REQ rising edge to output data invalid
rdo
All timing values are in nanoseconds.
© National Instruments Corporation
t
a*r
t
r*a
t
r*r
t
doa*
Description
Figure 3-13. 8255 Emulation Output Timing Diagram
3-17
Chapter 3
t
aa*
t
rr*
t
t
rdi
dir
t
rdo
ACK and REQ are shown as active low
Minimum
75
75
0
0
10
100
—
25
100
Timing Diagrams
Maximum
—
—
—
—
—
—
150
—
—
653X User Manual