LeCroy Advisor, Руководство пользователя

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USB Advisor User Manual Chapter 1: Overview
LeCroy Corporation
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1.3 Accurate Time Management
The Advisor USB2.0 Analyzer uses internal counter/timer circuitry to enable a reliable,
accurate (16.67 ns resolution) time stamping of recorded bus traffic. This timing
information is available both as a component of the graphical data display and as a
contribution to a variety of measurement and analysis functions. Any number of markers
can be added by the user to denote specific packets, and further timing measurements
can be made from one marker to another or from marker to trigger. All time fields are
presented as a time stamp, idle time, bit time or in a new time delta in either decimal or
hexadecimal format.
An essential feature of time management is that idle traffic does not consume the
Analyzer memory. Because of this unique technology, accurate timing calculations can
be made while still preserving valuable recording memory for important bus traffic.
1.4 Comprehensive Error Detection and Analysis
The Advisor USB2.0 Analyzer detects and alerts the user to every potential bus error,
protocol violation and/or combination thereof. The Analyzer contains circuitry in the
BusEngine™ to perform real-time triggering on multiple error conditions, such as PID
bad, bit stuffing bad, header or data CRC bad, end-of-packet bad, babble, loss of activity,
frame length violation, time-out or turn-around violation and data toggle violation. The
Analyzer program highlights all the hardware detected errors and further examines the
trace file for additional protocol errors, including wrong packet length, data payload
violation, and packet termination not on a byte boundary.
1.5 Real-Time Event Triggering and Capture Filtering
No attribute of a bus and protocol Analyzer is more important than its capacity for
extracting useful information from a crowded stream of bus traffic. The ability to
accurately identify, and selectively record, transactions of interest is the trait most
valuable to the user. The Advisor USB 2.0 Analyzer offers a unique approach to this
challenge. By using a set of recording resources, more than a dozen configurable
hardware building blocks can be optimized to perform a particular activity appropriate to
the task. A recording resource can independently await an initialization signal, monitor its
external environment (external signals, other resources) in search of a particular event
and take a subsequent action (triggering, inclusive or exclusive filtering, counting, etc.).
Under control of the user interface, these resources can be selected, configured and
combined to both search for complex trigger conditions and selectively capture the
associated transactions.
Thus, as well as triggering on basic events, such as specific bus conditions and packet
identifiers (PID) (see the Specifications section for a complete list), the Advisor USB2.0
Analyzer can easily manage the most challenging requirements. For example: "trigger on
the fifth occurrence of a SETUP Token device number nine", or "trigger on a SET
INTERFACE request, following a specified eight-byte bulk data pattern match from this
scanner, and do not capture any start-of-frame (SOF) packets."
The user can also configure the size of the recording memory, specify the pre/post-trigger
capture ratio, and truncate the capture of large data packets up to the first 256 bytes.