Tutorial: Understanding and Using FreeRTOS Software Timers

Hardware Timers are essential to most embedded applications: I use them mostly for triggering actions at a given frequency, such as acquiring data from a  sensor. With using an RTOS I can do a similar thing using a task: the task will run with a given frequency and I can periodic work in it. However, using a task might be too much overhead doing this. The good news is that there is a much more efficient way to do this in FreeRTOS with Software Timers. And this is what this tutorial is about: how to use Software Timers with FreeRTOS.

FreeRTOS Software Timers

FreeRTOS Software Timers

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Understanding FreeRTOS Task Stack Usage and Kernel Awareness Information

When using the FreeRTOS Task List in the Eclipse based MCUXpresso IDE, it shows the list of tasks with their stack size used. But with the default FreeRTOS settings it is not able to determine the correct stack size and shows a warning icon:

Warning for Stack Usage

Warning for Stack Usage

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Sneak Preview: DIY SMT Pick & Place Machine with OpenPnP

I apologize: I have not been blogging much in the past weeks :-(. One reason is that I’m working on a DIY SMT/SMD Pick&Place machine which keeps me busy most of my spare time :-). I admit that this project is not finished yet, but now is the time I can give a sneak preview: a SMD/SMT pick and place machine:

Pick&Place Machine

Pick&Place Machine

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McuOnEclipse Components: 1-Apr-2018 Release

It’s April Fool’s Day, but be assured this is not a joke ;-): I’m pleased to announce that a new release of the McuOnEclipse components is available in SourceForge. This release includes several smaller bug fixes and components have been upgraded for FreeRTOS V10.0.1.

SourceForge

SourceForge

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Performance and Runtime Analysis with FreeRTOS

One of the great things with the FreeRTOS operating system is that it comes with free performance analysis: It shows me how much time is spent in each task. Best of all: it shows it in a graphical way inside Eclipse too:

FreeRTOS Runtime Information in Eclipse

FreeRTOS Runtime Information in Eclipse

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Faster FreeRTOS Percepio Tracealyzer Streaming with Segger RTT

To solve the real hard problem of Embedded Systems development, I usually need all the data I can get from the target. The Percepio Tracealizer is such a tool which can stream application and FreeRTOS trace from the target over a Segger J-Link connection using the Segger RTT protocol. I’m using that combination a lot.

Streaming trace data that way does not need a dedicated hardware like ETM Trace. Using RTT is usually not much intrusive and affects the performance of the target in the 1-2% range (of course depending on the amount of data).

But what worried me for several weeks is that after moving to FreeRTOS V10.0.0 and the same time updating the Segger libraries, the target performance was heavily affected:

RTT Streamnig affects target performance

RTT streaming affects target performance?

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McuOnEclipse Components: 26-Dec-2017 Release

I’m pleased to announce that a new release of the McuOnEclipse components is available in SourceForge., which is supposed to be the last release for 2017 :-). This release features several smaller bug fixes, the new FreeRTOS V10.0.0 and extended device support.

SourceForge

SourceForge

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New Concept for 2018 Mini Sumo Roboter

Doing Mini Sumo robot competition is really fun, and there is yet another one coming to end the current university semester. For several years we have used our own sumo robot, and this is the one used in the course this year too. But for future and extended events we are exploring a new robot. I proudly present the concept of the next generation sumo robot for the year 2018:

Sumo Robot with Bluetooth module

Sumo Robot with Bluetooth module

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New FreeRTOS V10.0.0: Amazon, Segger SystemView and Percepio Tracealyzer

“Amazon FreeRTOS – IoT operating system for microcontrollers”: The announcement of FreeRTOS V10.0.0 was one of the biggest news last week for me. Not only is there now a Version 10, the bigger news is that FreeRTOS is now part of Amazon. Wow! Now this explains why Richard Barry (the founder behind FreeRTOS) was kind of hiding away for about a year: he joined Amazon as a principal engineer about a year ago. I think we all have to wait and see what it means for FreeRTOS.

Amazon FreeRTOS

Amazon FreeRTOS (Source: Amazon Web Site)

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McuOnEclipse Components: 25-Sept-2017 Release

I’m pleased to announce that a new release of the McuOnEclipse components is available in SourceForge. In this release more ARM Cortex devices/vendors are supported with different SDKs, plus it comes with several FreeRTOS enhancements for debugging highly optimized code.

SourceForge

SourceForge

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Using Multiple Memory Regions with the FreeRTOS Heap

ARM Cortex-M microcontrollers can have multiple memory controllers. This is a good thing as it allows the hardware to do multiple parallel memory read/writes. However this makes the memory map more complicated for the software: it divides the memory into different regions and memory segments.  This article is about how to enable FreeRTOS to use multiple memory blocks for a virtual combined memory heap:

FreeRTOS with Segmented Heap Memory

FreeRTOS with Segmented Heap Memory

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Troubleshooting Tips for FreeRTOS Thread Aware Debugging in Eclipse

FreeRTOS seems to get more and more popular, and I think as well because more and more debugger and Eclipse IDE vendors add dedicated debugging support for it.

FreeRTOS Threads in Eclipse

FreeRTOS Threads in Eclipse

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McuOnEclipse Components: 09-July-2017 Release

I’m pleased to announce that a new release of the McuOnEclipse components is available in SourceForge, with the following major changes and updates:

  • Complete refactoring for 1-Wire stack and DS18B20 temperature sensor components
  • Added HID Joystick device class to the FSL_USB_Stack
  • New SDK_Timer component to work with Kinetis SDK
  • New ST756P LCD driver component
  • New TSL2561 digitial temperature sensor driver
  • Added ReadByte() and WriteByte() GenericI2C functions
  • Added 64bit mapping functions to Utility
  • added configUSE_NEWLIB_REENTRANT and newlib reentrancy support to FreeRTOS
  • Pull resistor support for SDK_BitIO
  • Many smaller bug fixes and enhancements
SourceForge

SourceForge

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Using FreeRTOS with newlib and newlib-nano

For reliable applications, I avoid using functions of the standard libraries. They are banned for most safety related applications anyway. I do not use or avoid malloc(), printf() and all the other variants, for many reasons including the ones listed in “Why I don’t like printf()“. Instead, I’m using smaller variants (see “XFormat“). Or I’m using only the thread-safe FreeRTOS heap memory allocation which exist for many good reasons.

Things get problematic if malloc() still is pulled in, either because it is used by a middleware (e.g. TCP/IP stack) or if using C++. Dave Nadler posted a detailed article (http://www.nadler.com/embedded/newlibAndFreeRTOS.html) about how to use newlib and newlib-nano with FreeRTOS.

FreeRTOS Newlib Memory Allocation Scheme

FreeRTOS Newlib Memory Allocation Scheme

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McuOnEclipse Components: 06-May-2017 Release

I’m pleased to announce that a new release of the McuOnEclipse components is available in SourceForge, with the following changes and updates:

  • SEGGER SystemView updated to V2.42
  • More components to work with MCUXpresso SDK: GenericSWSPI, FXO8500 and SimpleEvents
  • SSD1351 display driver supports 128×128 pixel resolution and Adafruit 1.5″ breakout module
  • Extended FreeRTOS debug helper settings
  • GenericI2C: added ReadWordAddress8() and ReadWordAddress8() functions
  • RingBuffer with new Getn() and Update() functions
  • Utility with map(), constrain(), random() and randomSetSeed()
  • XFormat: new xsnprintf(), contributed by Engin Lee
  • OneWire protocol component with Maxim DS18B20 temperature sensor
  • Many smaller bug fixes and enhancements
SourceForge

SourceForge

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MCUXpresso IDE: Unified Eclipse IDE for NXPs ARM Cortex-M Microcontrollers

There are many mergers going on in the industry, and one of the largest one was in 2016 the integration of Freescale Semiconductor with NXP Semiconductors, with both providing Eclipse based IDE’s to their customer base. Consequently, the company merger triggered a merger of the IDE’s, and last week NXP has released the result: the MCUXpresso IDE.

MCUXpresso IDE

MCUXpresso IDE

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Tutorial: Using Eclipse with NXP MCUXpresso SDK v2 and Processor Expert

To me, software and tools are by far more important than the microcontroller. Because the silicon is a ‘one time kind of thing’, where the software has to be maintained and working over a longer time. And at least my software usually needs to be ported to a new device, so portability and available software and tools are critical to me.

The combination of MCUXpresso SDK (formerly Kinetis SDK) and Processor Expert is unfortunately not supported by NXP. But I have found a way to get them work together in a nice way, and this article is about making that combination possible :-).

SDKv2 Project with Processor Expert

SDKv2 Project with Processor Expert which is supposed not to work together

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Better FreeRTOS Debugging in Eclipse

With debugging FreeRTOS applications in Eclipse, it is a big to have views available showing all the threads, queues, timers and heap memory allocation. One of the best Eclipse plugins are the one NXP provides for FreeRTOS: they are free of charge and give me pretty much everything I need. However, if you are not that familiar with FreeRTOS itself, here are a few tips to get more out of the plugins.

Better FreeRTOS Debugging in Eclipse

Better FreeRTOS Debugging in Eclipse

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McuOnEclipse Components: 12-Mar-2017 Release

I’m pleased to announce that a new release of the McuOnEclipse components is available in SourceForge, with the following main features and changes:

  • Wait: Busy-Waiting using ARM DWT cycle counter
  • Percepio FreeRTOS+Trace: Updated to version 3.1.1, simplified usage of streaming and snapshot mode
  • GenericSWI2C: MCUXpresso SDK can be used with the bit-banging I2C driver support
  • FreeRTOS: includes updates of the 9.0.1 release, ‘optimized task selection, enabled MPU support (experimental)
  • Graphical GUI drivers for screens, windows, icons, headers, text widgets and more
  • SSD1351: display driver for Solomon Systech SSD1351 display
  • More components are now supported by the McuLibConfig settings
  • Many other smaller bug fixes and enhancements

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Percepio FreeRTOS Tracealyzer Plugin for Eclipse

Good news for everyone using Eclipse, FreeRTOS and Percepio Tracealyzer: Percepio has released an Eclipse plugin which makes snapshot tracing very easy and convenient using the a GNU gdb debugger in Eclipse like Kinetis Design Studio:

Eclipse with Percepio Tracealizer

Eclipse with Percepio Tracealyzer

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