Steps to use FreeRTOS with newlib reentrant Memory Allocation

Reentrancy is an attribute of a piece of code and basically means it can re-entered by another execution flow, for example by an interrupt or by another task or thread. This is an important concept and still a lot of code ‘in the wild’ does violate reentrancy. As a result the application crashes immediately in the best case. Worse it crashes randomly or even worse it behaves incorrectly 😦 .

Reentrancy is always a concern if using standard library functions, including printf() or malloc(). FreeRTOS offers a reentrant wrapper to the standard malloc() and free() (Memory Scheme 3)

Running FreeRTOS with reentrant newlib

Running FreeRTOS with reentrant newlib

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FreeRTOS and Eclipse Indexer for >5K Lines Source Files

Eclipse has a great built-in source code parser and browser (aka ‘Indexer’). It is basically a built-in compiler which parses the source files and assists the user with code completion and navigation help, making Eclipse this awesome productivity tool. On the downside this background parsing could potentially slow down things, and therefore Eclipse has some default settings to prevent this. Unfortunately, the FreeRTOS Kernel ‘tasks.c’ file is above-and-beyond of a ‘sane’ source file and will hit the default limits: as a result the ‘tasks.c’ file is not indexed and things like ‘Open Declaration‘ might not work for the file ‘tasks.c’.

Open Declaration

Open Declaration

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Tweaking MCUXpresso IDE Black Theme

‘Dark’ or ‘Black’ themes are on vogue: some love it, some do not care. The good thing is that we all have a choice. Things are getting improved on the host OS (Windows/Linux) side, but the challenge is still on the application side, but things are getting better. This is true for the Eclipse based IDEs too, with the NXP MCUXpresso IDE V11.2.1 just recently released: it comes with improved Dark Theme support:

Tweaked MCUXpresso IDE Dark Theme

Tweaked MCUXpresso IDE Dark Theme

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Mobile Teacher Tool, Rev 2 by Gerhard

It is always great to see if someone is picking up my work and produces something even better :-). In this case, Gerhard Székely took my DIY Portable Video Conference, Sharing and Teaching Device and created an awesome version of it:

Camera to the front

Camera to the front

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Import Projects from git into Eclipse

As a VCS (Version Control System) I’m using git in all my projects. And not only for software or firmware projects: I’m using it for hardware design (KiCAD, FreeCAD, …) or for documentation (LaTeX, …) too.

The nice thing with the Eclipse IDE is that it supports nice git integration, making importing projects from git repositories easy.

Import Projects from git

Import Projects from git

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DIY Portable Video Conference, Sharing and Teaching Device

COVID-19 is by far not over, and in Switzerland the infection rate is going up again (2nd wave?). During the spring 2020 semester university lock-down we moved pretty much everything to a ‘distance learning’ setup. With that experience and with the request to prepare for the fall semester, I have constructed a DIY conference and teaching device which should make things simpler and easier: a combination of video camera, speaker phone and a muting device:

Desk with Communicator

Desk with Communicator C2020

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How to get Data off an Embedded System: FatFS with USB MSD Host and FreeRTOS Direct Task Notification

This is a follow-up article of my earlier project presented in “FatFS, MinIni, Shell and FreeRTOS for the NXP K22FN512“. I wanted to extend it with a USB MSD (memory stick) device: The USB storage device gets automatically mounted, and depending on a configuration (.ini) file on the memory device I can perform various actions, for example automatically copy data from the SD card to the USB device. For example the system logs data, and to get the data I insert the memory stick, it copies the data on it and automatically unmounts it, and I can remove the memory stick.

FRDM-K22F USB Host Mode with Memory Sticks

FRDM-K22F USB Host Mode with Memory Sticks

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Behind the Canvas: Making of “60 Billion Lights”

As promised I’m going to share more details about the “60 Billion Lights” project. It is about a project to build a piece of electronics behind a 100×50 cm canvas to show animations or to display information like temperature, humidity, weather, time or just any arbitrary text.

Make it

Writing text

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McuLog: Logging Framework for small Embedded Microcontroller Systems

An essential tool especially developing larger applications or distributed firmware is to use logging. This article presents an open source logging framework I’m using. It is small and easy to use and can log to a console, to a file on the host or even to a file on an embedded file system as FatFS.

Log Output

Log Output

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FatFS, MinIni, Shell and FreeRTOS for the NXP K22FN512

I’m using the NXP Kinetis K22FN512 in many projects, either with the FRDM-K22F or on the tinyK22: with 120 MHz, 512 KByte FLASH and 128 KByte it has plenty of horsepower for many projects. The other positive thing is that it is supported by the NXP MCUXpresso IDE and SDK. I have now created an example which can be used as base for your own project, featuring FreeRTOS, FatFS, MinIni and a command line shell.

FRDM-K22F with SD Card

FRDM-K22F with SD Card

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