faster firmware development with freertos and tracealyzer

Faster Firmware Development with Tracealyzer


Dr. Johan Kraft, CEO/CTO/Founder, Percepio [email protected]


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Source code - not the full picture!

Software behavior depends on timing

Interrupts? Critical Sections? Execution times? Dynamic memory allocation?RTOS Scheduling? Timeouts? Priorities? Blocking? Triggering?

CPU usage? Response times? Periodicities?

What is actually going on in the runtime system?


Software Tracing

Software-defined TracingRecorder module + instrumentationrecords RTOS and application logging.


Trace Visualization – See the Runtime World


Improves Development Efficiency and Quality

ValidationCode running as intended?

DebuggingRTOS and timing issues

ProfilingRAM and CPU usage per

task?

DocumentationVisualize designs or issues

TrainingRTOS and other APIs

“Tracealyzer has doubled our development speed. Problems that otherwise would take days to solve are obvious with this tool and just a quick fix.”Alex Pabouctisids, Lead Firmware Engineer, Flyability.

“In less than 5 days from running the tool, we improved the performance of our graphic rendering engine by 3x!”Terry West, CEO, Serious Integrated Inc.


Main Trace ViewVertical time-line- Task scheduling- Preemptions- Interrupts- RTOS API calls- Blocking- Resumes- Timeouts- RTOS Tick- User Events


Kernel Object HistoryDouble-click on a queue, semaphore or mutex label to see all operations and states of the selected kernel object.

Track queue messages between send and receive or vice versa. Double-click showsthe event in main trace view.

Faster Firmware Development with TracealyzerSummary of task and ISR communications via kernel objects (queues, …)

Communication Flow

Faster Firmware Development with TracealyzerCPU Load Graph: Use of processor cycles, per task and ISR.Kernel Object Utilization: Size of queues over time.

Faster Firmware Development with TracealyzerUser Event Signal Plot: Any data logged as ”User Events”


Customer Case 1


Case 1 – Timing variations

Task should execute every 5 ms, but random variations of 1-2 ms!


Compare with the Task Trace...

Something delays the activation of SamplerTask, probably ControlTask!


Why delayed preemption? Looking closer...

ControlTask seems to disable interrupts!

No OS Ticks for 2.5 ms


Showing all logged events...

ServerTask also logged ”Updating file”, but uses a Mutex instead!


When using a Mutex instead of disabling interrupts...

Now perfect 5 ms periodicity!


Customer Case 2


Watchdog reset? User events added…


Why doesn’t SamplerTask reset the Watchdog?


Why is ControlQueue blocking?


So the queue gets full... Why is ControlTask is not reading the queue fast enough?

ServerTask has higher priority than ControlTask, does not leave enough cycles when high load!


With swapped task priorities – problem solved!


Integrating the Recorder Library

• RTOS events is traced automatically via Percepio’s ”instrumentation layer” for the supported RTOS– For FreeRTOS:

• Enable ”useTRACE_FACILITY” in FreeRTOSConfig.h• Include ”trcKernelPort.h” in FreeRTOSConfig.h.• Call the recorder’s init function early in main().• Start and stop the recorder when desired.

– Similar for Micrium, SafeRTOS and embOS.• Accurate hardware timestamping ”out-of-the-box” for

most MCUs (see trcHardwarePort.h)– ARM Cortex-M, Renesas RX, Microchip PIC32, …– Easy to implement new ports via macros.

• See http://percepio.com/gettingstarted


[email protected]

Evaluate Tracealyzer!http://percepio.com/download

mailto:[email protected]

http://percepio.com/download



faster firmware development with freertos and tracealyzer

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