LeCroy DDA 7 Zi series, Руководство оператора

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Operator's Manual
WP700Zi-OM-E-RevA
228
SPI Ack Setup
Use this setup to choose whether you want to add an Acknowledge bit condition to your ADDR,
ADDR+DATA, FRAME LENGTH, or EEPROM trigger condition. DON’T CARE would be the
most common setup, although ACK or NO ACK might be a useful condition to add for an unusual
or hard to find I
2
C problem. An example of this would be triggering on an EEPROM write
(selected by an ADDR trigger) where the EEPROM failed to acknowledge a byte written.
Overview of Serial Bus Activity
The combination of Serial Data Triggering, Decoding, and normal oscilloscope features is a powerful combination
of tools that can make it very easy to find latent Serial Data hardware or software problems in your circuit. No
longer is the oscilloscope a tool just for the hardware engineer. Now the software engineer can also easily
visualize the Serial Data signals and relate it to programming code and operation. The TD options can enable the
hardware engineer and software engineer to “speak the same language” when it comes to system debugging and
performance checking.
Some common Serial Data analysis needs and methods are discussed next.
Capturing Long Pre-Trigger Time
LeCroy oscilloscopes are available with optional very long acquisition memory. For instance, the WaveRunner Xi
Series oscilloscopes can capture up to 12.5 Mpts on 4 channels, or 25 Mpts on 2 channels. If your Serial Data
signals are 1 Mb/s, and you sample at the minimum required and available sample rate (5 MS/s, you would be
able to capture 5 seconds of Serial Data traffic. If you wish, this can be 100% pre-trigger, 100% post-trigger, or
something in between.
1. Adjust Pre-Trigger and Post-Trigger time by adjusting the
D
ELAY
knob on the oscilloscope’s front panel.
2. Optimize your Sample Rate or Memory Length by accessing
the Horizontal Dialog in your oscilloscope and selecting either
Set Max Memory mode or Fixed Sample Rate mode.
3. If you choose to Set Max Memory, you can decrease the
memory usage so that you will not sample at too high a
sampling rate (too high a sampling rate will slow down the
decoding algorithm). Then adjust your timebase setting to as
long as necessary to capture the event. Note that you must
make sure that your timebase setting and memory length
combined do not result in too low a sampling rate or adequate
capture and decode will not be performed.
4. More commonly, you will probably choose to fix the sampling
rate to a specific value that provides you with the