Serial Bus Decoding & Triggering, Search & Navigation, and Segmented Acquisition Labs
4
4000 X-Series Oscilloscopes Advanced Training Guide
135
20
On the top right of the waveform display, tap the
double down arrows
to expand
the lister to half screen mode. The lister will display a time organized list of all
decoded traffic.
21
Zoom out the scope's timebase to
100 µs/div
. As the lister scrolls data, notice
the NAK packet that is appearing. Let's trigger on that.
22
In the
Trigger Menu
, select
Handshake Packet
from the
Trigger: Data Packet
menu.
Change the
PID
to
NAK
.
The trigger is now stable, and displaying the entire training signal. Tap the double
down arrows at the top right of the display to expand the lister to full screen, as
. The eleven decoded messages represent four transactions (you
may see more than eleven rows, as the training signal has repeated over the
course of 1 ms). The first is a successful IN packet, then DATA0, with an ACK. The
second transaction has a packet with a corrupt PID (MDATA is only used in
full-speed applications), but follows with packets of DATA1 and an ACK, so an
engineer debugging the circuit might assume it was originally an IN packet with a
bit flip in the PID check. Next is an IN with a NAK, and finally a last successful IN,
DATA1, and ACK.
Figure 91
Triggering on IN Token packets.
Содержание 4000 X-Series
Страница 12: ...12 4000 X Series Oscilloscopes Advanced Training Guide 1 Getting Started...
Страница 156: ...156 4000 X Series Oscilloscopes Advanced Training Guide A Oscilloscope Block Diagram and Theory of Operation...
Страница 166: ...166 4000 X Series Oscilloscopes Advanced Training Guide B Oscilloscope Bandwidth Tutorial...
Страница 168: ...168 4000 X Series Oscilloscopes Advanced Training Guide C Related Keysight Literature...