Keysight 4000 X-Series, Руководство по продвинутой подготовке

Страница: 134 / 170

134 4000 X-Series Oscilloscopes Advanced Training Guide
4
Serial Bus Decoding & Triggering, Search & Navigation, and Segmented Acquisition Labs
Note that your scope should still be triggering on random edge crossings of
channel-1. Let's now set up the scope to a specific trigger point - when it detects
an IN token packet.
17
Press the
[Trigger]
front panel key; then select Serial 1 (USB) .
18
Tap the Trigger on: softkey; then select Token Packet .
19
Tap the PID softkey, and select IN as the token we want to trigger on.
You should now see stable waveform traces on your scope's display similar to
Figure 91 . Of course, there is still a bit of confusion as it is triggering on multiple IN
packets, which are rapidly flashing on the bottom of the screen in the blue decode
area. Let's zoom out and see the scope's ability to list all decoded traffic, to
discover a unique and stable trigger point.
Figure 90 Fast, hardware decoding of USB traffic.