1
How it works
The conditions, their logic and the actions are evaluated by the trace hardware.
The failure shows up on the thousandth call or after a mode change: a condition, not a time window. ChipTrace programs the condition once, at boot; the hardware then evaluates it at every instruction, with no code added and no core stalled.
2
Seven building blocks
Each one programmed by the ChipTrace library.
ETM logic
Event packets
A marker in the trace at a chosen address, task or input.
Every run of the brake handler, without a printf.
ETM logic
Counters
Count any event; at zero, open the trace or write a marker.
Trace call 1000, not the 999 that worked.
ETM logic
Sequencer
Four states: trace only after A, then B.
The fault handler, but only after the switch to run mode.
What is recorded
Data trace
The address and value of loads and stores, on the ranges you choose (Cortex-M7).
Who overwrites the calibration table, and with which value.
What is recorded
DWT
Cortex-M7 watchpoints, PC sampling and interrupt trace.
Every write to a flag, with its value and the code behind it.
Beyond the ETM
Performance Monitor
Cortex-A53 counters: cycles, cache refills, exceptions, also as markers in the trace.
Count the task switches in one function, and see where each one happened.
Beyond the ETM
CTI
An event on one core starts the trace of another.
The Cortex-M7 writes a mailbox: the Cortex-A53 trace starts there.
Validated
74 board tests
On S32G3: Cortex-A53 42, Cortex-M7 32. Run and checked by T32Pilot.
How T32Pilot tests →3
Example: a frame sent the wrong way
The trace hardware starts the capture itself, with no code added to the application.
1
The bug
In a gateway, one core receives the frames (Cortex-M7), another one routes them (Cortex-A53). Once in thousands of frames, one is sent the wrong way.
2
What you ask
Record the routing core only after the receiving core has handed it a frame.
3
What you get
The trace of that routing, and nothing else, kept to be read after the fault.
MOVE.B training
Learn the logic behind the triggers
ETM resources, CTI, DWT and the Performance Monitor are covered in depth in MOVE.B's CoreSight and core courses.