80
3000 X-Series Oscilloscopes Advanced Training Guide
4
Serial Bus Decoding & Triggering, Search & Navigation, and Segmented Acquisition Labs
You should now see four digital waveforms captured by the scope’s digital
channels of acquisition similar to
. These SPI training signals are
being generated by the scope’s built- in pattern generator and routed
directly to the scope’s digital acquisition system; bypassing the logic probe.
Note that in a real measurement application such as this, you would use
the scope’s analog input channels and/or logic probe to capture these
signals from your system.
D9 is the MOSI data signal (Master- out, Slave- in), and D8 is the MISO
data signal (Master- in, Slave- out). You can also think of these signals as
serial data- out and serial data- in relative to the Master. D7 is the SPI
clock signal (CLK), and D6 is the chip select low- enable signal (~CS). This
signal is sometimes referred to as Slave- select (SS). Note that the “~”
symbol simply means “not” or “low- enable”. Let’s now set up the scope to
decode these SPI signals.
12
Press the
[Serial]
front panel key.
13
Press the
Mode I
2
C
softkey; then select
SPI
using the Entry knob.
14
Press the
Signals
softkey.
15
Press the
Clock
softkey; then select
D7
as the clock source using the
Entry knob.
16
Press the
(Back) front panel button to return to the previous menu.
17
Press the
MOSI
softkey; then select
D9
using the Entry knob.
18
Press the
(Back) front panel button to return to the previous menu.
Figure 55 Capturing 4-wire SPI signals using the scope’s digital channels of acquisition
(MSO).
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