Application source code and header files for on-core time-tracing of the Aurix TriCore.

This library can be used, if compiled with an Aurix Tricore application, to trace the application's execution time at specified points in the program. Timestamps are saved with an ID inside a buffer in the scratchpad memory of the core running the application.

The Aurix TC26x, TC27x and TC29x processors are equipped with both a system timer (STM) and a cycle counter (CCNT) for each core. CCNT and STM work at different (configurable) frequencies. Each time source has its own PROs:

• Same time source for all cores, timestamps can be compared

• Finer granularity

• Faster access

• No contention on the peripheral bus

STM is not only slower (as it is connected to the SPB peripheral bus) but may also be cause of interference in case multiple cores access the STM at the same time.

Separate trace buffers are provided for each core, stored in the core's data scratchpad (DSPM). This draws several benefits when compared to off-core storage:

• Faster write accesses: DSPM is local so no bus arbitration

• No race conditions: each core has its own data structure

• No need for storing the core ID

Both CCNT and STM are memory mapped. CCNT is accessible at the same address on every core while STM provides different addresses for different cores in order to reduce interference. Three source files (coreX_tracing.c) are provided that have to be compiled with the application depending on which core it is going to run on.

Traces are stored in a buffer (Trace_Buffer) as pairs (ipoint_id, timestamp). By default, Trace_Buffer holds 1024 of such pairs. The size of the trace buffer can be configured by defining the macro IPOINT_TRACE_ BUFFER_SIZE. IPOINT_TRACE_ BUFFER_SIZE is required to be a power of 2.

Trace_Buffer is put into the .TRACE_BUFFER section that has to be defined in the linker script. If the HighTech toolchain is being used the following section definition has to be included at the very beginning of the SECTIONS part of the linker script.

.TRACE_BUFFER : { 
 *(.TRACE_BUFFER .TRACE_BUFFER.*) 
} > DMI_DSPR

By default timestamps are captured from the STM clock. To use CCNT, instead, the macro TRACE_CYCLE_COUNTER can be defined before including tracing.h. In order to use the core cycle counter, before accessing the tracing capabilites CCNT has to be enabled on each core. To that extent tracing.h provides the macro ENABLE_CYCLE_COUNTER.

A macro IPOINT is available that stores in the trace buffer the specified ipoint id and the current timestamp.

To extract traces from the running target the host deamon available here can be used. It supports trace extraction via the DAP miniWiggler v3. Otherwise, a debugger as Lauterbach's can be used.