Tektronix DPO4032, Руководство пользователя

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Trigger Setup
I
2
C, SPI, CAN, LIN, and FlexRay Bus Trigger Data Matching
Rolling window byte matching for I
2
C, SPI, and FlexRay.
To use a rolling window to trigger on data, you de fi ne the
number of bytes to match. Then the oscilloscope uses a rolling window to fi nd any match within a packet, with the window rolling
one byte at a time.
For example, if the number of bytes is one, the oscilloscope will attempt to match the fi rst byte, second byte, third, and so
on within the packet.
If the number of bytes is two, the oscilloscope will try to match any two consecutive bytes, such as one and two, two and three,
three and four, and so on. If the oscilloscope
fi nds a match, it will trigger.
With FlexRay, obtain a rolling window match by setting the Byte Offset to Don’t care . Do this by pressing the front-panel Trigger
button, followed by setting the lower-bezel Type to Bus , Trigger On to Data , pressing Data , and entering the byte offset with the
side menu and multipurpose knob a ..
Speci fi c byte matching (non-rolling window matching for a speci fi c position in the packet) for I
2
C, SPI, CAN, and
FlexRay.
You can trigger on a speci fi c byte for I
2
C, SPI, CAN, and FlexRay in several ways:
For I
2
C and SPI, enter the number of bytes to match the number of bytes in the signal. Then use don’t cares (X) to mask the
bytes that you are not interested in.
For I
2
C, push the lower-bezel Trigger On to trigger on Address/Data . Push Address . On the side-bezel menu, push Address ,
and rotate multipurpose knobs a and b as needed. Set the address to don’t cares (X) if you want to mask the address. The
data will be matched starting at the fi rst byte without using a rolling window.
For CAN, triggering occurs when the user-selected data input matches the data and quali fi er in the signal starting at the fi rst
byte. Set the number of bytes to match the number of bytes of interest. Use the data quali fi er to perform: =, !=, <, >, >=,
and <= operations. Triggering on identi fi er and data always matches the identi fi er and data selected by the user, with the
data starting at the fi rst byte. No rolling window is used.
154 MSO4000 and DPO4000 Series Oscilloscopes User Manual