Standalone SWO

SWO (Single Wire Output) in ARM cores is probably one of the most under-used features. Which is surprising, because SWO can be very useful. In a nut shell: SWO is a single wire output pin/signal channel which can provide lots of different data, like PC sampling for coverage information, interrupt tracing data or ‘uart-like’ text packets.

SWO output from application
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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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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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Using FatFS and MinINI with the NXP LPC55S16 EVK

For a research project we selected the NXP LPC55S16 but because it has due the silicon shortage it is not available probably for the next 52 weeks (yikes!) we can use the EVK Board.

The FatFS file system from Elm Chan is the de-facto file system for many embedded systems. As such it comes integrated with silicon vendor SDKs like the NXP MCUXpresso SDK. The problem is that the SDK only has examples for things on the board, and because that board does not have a SD card socket, no example for using FatFS with an SDK card is provided :-(. So I had to create one, and you can get it from GitHub.

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Visual Studio Code for C/C++ with ARM Cortex-M: Part 4 – Debug

The previous parts were about installation, project setup and building. This one is about debugging an ARM Cortex-M Microcontroller with Visual Studio Code:

Cortex-M4 (NXP K22FN512) Debugging with Visual Studio Code
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Visual Studio Code for C/C++ with ARM Cortex-M: Part 1 – Installation

For a few months I’m learning and using Rust. I’m still learning, but I’m very impressed by the powerful and cool programming language, the vibrant ecosystem, the advanced concepts behind it and by the tools. With learning Rust I have been using the Visual Studio Code IDE and it works great for Rust. But I was wondering: could I use it for my ‘usual’ C/C++ development on ARM Cortex-M devices too? The answer is a clear ‘yes’, and this mini series of articles should get you up and running too.

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Attach with the Debugger to a Running Target

Sometime I’m pretty sure I wrote about a topic I can find or refer to, and I was pretty sure I did write about ‘attaching to a running target’ using MCUXpresso IDE in an article, but Google does not find it? The only rational outcome is that I can blame Google and I have to come up with a potential duplicate ;-).

Anyway: attaching to a running target is such an essential life saver it deserves a dedicated article.

Haltet Target
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