Technical data

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 seen in Figure 92. 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.