
EM358x
Rev. 0.4
245
13 Instrumentation Trace Macrocell (ITM)
The EM358x integrates the standard ARM
®
Instrumentation Trace Macrocell (ITM). The ITM is an application-
driven trace source that supports printf style debugging to trace software events and emits diagnostic system
information from the ARM
®
Data Watchpoint and Trace (DWT). Software using the ITM generates Software
Instrumentation Trace (SWIT). In addition, the ITM provides coarse-grained timestamp functionality. The ITM
emits trace information as packets, and these packets are sent to the Trace Port Interface Unit (TPIU). Three
sources can generate packets. If multiple sources generate packets at the same time, the ITM arbitrates the order
in which the packets are output. The three sources, in decreasing order of priority, are:
Software trace. Software can write directly to ITM stimulus registers, emitting packets.
Hardware trace. The DWT generates packets that the ITM emits.
Time stamping. Timestamps are emitted relative to packets and the ITM contains a 21-bit counter to generate
the timestamps.
The Ember software utilizes the ITM for efficiently generating debug data. Altering the ITM configuration may
conflict with Ember debug output.
For further information on the ITM, contact customer support for the ARM
®
Cortex
TM
-M3 Technical Reference
Manual, the ARM
®
CoreSight
TM
Components Technical Reference Manual, the ARM
®
v7-M Architecture
Reference Manual, and the ARM
®
v7-M Architecture Application Level Reference Manual.
Содержание EMBER EM358 series
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