Position-Independent Code with GCC for ARM Cortex-M

Welcome to ‘Alice in Wonderland‘! For a university research project using an ARM Cortex-M33 we are evaluating position-independent code as way to load applications or part of it with a bootloader. It sounds simple: just add -fPIC to the compiler settings and you are done.

Unfortunately, it is not that simple. That option opened up a ‘rabbit hole’ with lots of wonderful, powerful and strange things. Something you might not have been aware of what could be possible with the tools you have at hand today. Leading to the central question: how is position-independent code going to work with an embedded application on an ARM Cortex-M?

Let’s find out! Let’s start a journey through the wonderland…

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Visual Studio Code for C/C++ with ARM Cortex-M: Part 7 – FreeRTOS

This is a new article in my series about using Microsoft Visual Studio Code: After installation, project setup, building, debugging, setting up a kit and IntelliSense. This one is about setting up and using FreeRTOS:

Microsoft Visual Studio Code with Debugging FreeRTOS application on ARM Cortex-M
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Finding Memory Bugs with Google Address Sanitizer (ASAN) on Microcontrollers

Dangling pointers and memory corruption problems are nasty issues for any developer, and usually hard to find and locate in the code. Luckily Google has developed an open source tool to solve such issues: the Address Sanitizer (ASAN). The tool is available for x86 and other desktop style architectures, including Android and Linux. This article describes how ASAN can be used for an embedded target, e.g. ARM Cortex-M4 or similar.

Catching memory errors on ARM Cortex-M4F with ASAN
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View to the South

Fantastic view to the South today on a hike around the ‘Engelstock’:

View to the South

The snow covered Swiss Alps in the background with Ingenbohl-Brunnen and Lake Lucerne in the middle and Lake Lauerz on the right. If you want to see the view from the peak (Mt. Hochflue) on the right, see this post.

Happy viewing:-)

Placing Code in Sections with managed GNU Linker Scripts

Managed linker scripts are great on one side: the simplify the otherwise complex GNU linker script handling. On the other side it requires knowledge how to tweak them in case ‘non-standard’ behavior is needed.

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Visual Studio Code for C/C++ with ARM Cortex-M: Part 6 – IntelliSense

The previous parts were about installation, project setup, building, debugging and setting up a kit. This one is about setting up IntelliSense for Cross Development in Visual Studio Code which allows for browsing symbols or code completion:

Code Completion in Visual Studio
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SWO with ARM Cortex-M33

One major concern of embedded system development is performance. Microcontroller have more MHz than in the past, but embedded applications are all about timing and real-time aspects.

The challenge is: how to get data off the target in realtime? SWO can help with this….

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Recovering Cortex-M Microcontroller with a Power Glitch

If a Cortex microcontroller is unresponsive to a debug connection for various reasons, then this trick might help to recover that device for you. All you need is a debug probe from PEMICRO and a utility.

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