306
Keysight InfiniiVision 1200 X-Series and EDUX1052A/G Oscilloscopes User's Guide
28
SPI Triggering and Serial Decode
In the SPI Chip Select menu:
a
Press the
Frame by
softkey to select a framing signal that the oscilloscope will
use for determining which clock edge is the first clock edge in the serial
stream.
You can set the oscilloscope to trigger during a high chip select (
CS
), a low
chip select (
~CS
), or after a
Timeout
period during which the clock signal has
been idle.
•
If the framing signal is set to
CS
(or
~CS
), the first clock edge as defined,
rising or falling, seen after the
CS
(or
~CS
) signal transitions from low to
high (or high to low) is the first clock in the serial stream.
Chip Select
— Press the
CS
or
~CS
softkey; then, turn the Entry knob to
select the channel that is connected to the SPI frame line. The label (~CS
or CS) for the source channel is automatically set. The data pattern and
the clock transition must occur during the time when the framing signal is
valid. The framing signal must be valid for the entire data pattern.
•
If the framing signal is set to
Timeout
, the oscilloscope generates it's own
internal framing signal after it sees inactivity on the serial clock line.
Clock Timeout
— Select
Clock Timeout
in the
Frame by
softkey, then select
the
Timeout
softkey and turn the Entry knob to set the minimum time that
the Clock signal must be idle (not transitioning) before the oscilloscope
will search for the Data pattern on which to trigger.
The Timeout value can be set anywhere from 100 ns to 10 s.
When you press the
Frame by
softkey, the
Display Info
graphic changes to
show timeout selection or the current state of the chip select signal.
b
Press the
Threshold
softkey; then, turn the Entry knob to select the chip select
signal threshold voltage level.
The threshold voltage level is used in decoding, and it will become the
trigger level when the trigger type is set to the selected serial decode slot.
When
Display Info
is enabled, information about the selected signal sources and
their threshold voltage levels, as well as a waveform diagram, appears on the
screen.
