Texas Instruments TMS320 Series, User Manual

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Instrumentation APIs
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3.5 Instrumentation APIs
Effective instrumentation requires both operations that gather data and
operations that control the gathering of data in response to program events.
DSP/BIOS provides the following three API modules for data gathering:
❏
LOG (Event Log Manager). Log objects capture information about
events in real time. System events are captured in the system log. You
can configure additional logs. Your program can add messages to any
log.
❏
STS (Statistics Object Manager). Statistics objects capture count,
maximum, and total values for any variables in real time. Statistics about
SWI (software interrupt), PRD (period), HWI (hardware interrupt), PIP
(pipe), and TSK (task) objects can be captured automatically. In addition,
your program can create statistics objects to capture other statistics.
❏
HST (Host Channel Manager). The host channel objects described in
Chapter 7, Input/Output Overview and Pipes , allow a program to send
raw data streams to the host for analysis.
LOG and STS provide an efficient way to capture subsets of a real-time
sequence of events that occur at high frequencies or a statistical summary of
data values that vary rapidly. The rate at which these events occur or values
change may be so high that it is either not possible to transfer the entire
sequence to the host (due to bandwidth limitations) or the overhead of
transferring this sequence to the host would interfere with program operation.
DSP/BIOS provides the TRC (Trace Manager) module for controlling the data
gathering mechanisms provided by the other modules. The TRC module
controls which events and statistics are captured either in real time by the
target program or interactively through the DSP/BIOS Analysis Tools.
Controlling data gathering is important because it allows you to limit the
effects of instrumentation on program behavior, ensure that LOG and STS
objects contain the necessary information, and start or stop recording of
events and data values at run time.
3.5.1 Explicit versus Implicit Instrumentation
The instrumentation API operations are designed to be called explicitly by the
application. The LOG module operations allow you to explicitly write
messages to any log. The STS module operations allow you to store statistics
about data variables or system performance. The TRC module allows you to
enable or disable log and statistics tracing in response to a program event.