Round MetaClockClock

It has been a while since my last MetaClockClock, and with the continued shortage of electronics on the market I had no chance to order new parts. But I still had some remaining parts, and with the modular design of the ’round’ clocks I was able to build up another one, but this time with even less than the usual minimum of 24 clocks:

So if you are up to build a MetaClockClock with less clocks, this might be the way for you.

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Optimized Vinyl Cutting G-Code Tool Path with DXF2GCODE

G-Code (or RS-274) is a widely used protocol for CNC machines. I have added vinyl cutting capabilities to the Shapeoko desktop CNC recently (see DIY Vinyl Cutting Drag Knife for Desktop CNC), however cutting vinyl with a drag knife is whole different story compared cutting materials like wood or aluminum. As with many other things, it is about handling all corner cases properly.

Expected and not expected results cutting vinyl
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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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MetaClockClock Build Instructions

If you are not aware (yet?): it looks like the COVID pandemic caused a global silicon and microcontroller shortage with lead times >50 weeks in some cases. The microcontroller I have used for the MetaClockClock build (see “New MetaClockClock V3 finished with 60 Clocks” and “MetaClockClock V4 for the Year 2021“) is affected by this too, but I had luck and still enough microcontrollers to build a few more boards.

So I still have enough for building a new variant with it (not finished yet). While everyone else is waiting for the devices to arrive, here are more details and instructions for your own build.

MetaClockClock Temperature Display

MetaClockClock Temperature Display

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Tutorial: GNU Coverage with MCUXpresso IDE

If you are developing Linux or desktop applications with GNU tools, you  very likely are familiar with gcov: the GNU coverage tool. It collects data what parts of the code gets executed and represents that in different formats, great to check what is really used in the application code or what has been covered during multiple test runs.

Coverage Information with gcov

Coverage Information with gcov

line never executed

line never executed

GNU coverage is possible for resource constraint embedded systems too: it still needs some extra RAM and code space, but very well spent for gathering metrics and improves the firmware quality. As I wrote in “MCUXpresso IDE V11.3.0 for 2021” things are now easier to use, so here is a short tutorial how to use it.

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NXP published MCUXpresso SDK 2.9.0 on GitHub

There are many different aspects of Open Source projects: It is not only about the fact if the sources are available (‘open’). It is about the licensing terms (how permissible is it, what can I do with it), maintenance and continuous development (what has changed between releases), how and where is it delivered (Sourceforge, dedicated distribution, packaging) up to collaboration (how can I contribute or submit issues).

NXP has now published the MCUXpresso SDK on Github:

MCUXpresso SDK on GitHub

MCUXpresso SDK on GitHub

Something I was waiting for a long time.

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assert(), __FILE__, Path and other cool GNU gcc Tricks to be aware of

It is always good to have a close look what ends up in a microcontroller FLASH memory. For example using EHEP Eclipse plugin to inspect the binary file:

Source File Name in Binary Image

Source File Name in Binary Image

Obviously it has path and source file information in it. Why is that? And is this really needed?

What about:

  • Privacy: the path or file name might expose information (secret project name?) or might be used for reverse engineering?
  • Size: The strings add up to the final data/FLASH size, so this increases the need for ROM space?

So let’s have a look what is the reason for this and how it could be avoided or at least reduced.

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Hey Google: Find ‘Error from StubMonSemihost: “monitor” command not supported by this target.’

Something what I say quite often is: “Google is your friend”. It means that the answer to many questions can be found with an internet search engine. And I have to admit that I have to ‘google’ my own articles to find solutions for problems I feel I have seen in the past too :-).

But for the one problem below I did not find anything: not on my own blog, and not anywhere else in the internet:

Exception

Exception

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MCUXpresso IDE V11.3.0 for 2021

I’m in the middle of the university exam season: means writing exams and do grading. The same time the new semester is approaching too and I need to prepare the new course material. For the classes using NXP parts I’m using the Eclipse based MCUXpresso IDE, and I just received the announcement that a new version V11.3.0 is available: time to check out what is new.

MCUXpresso IDE v11.3.0 (Build 5222)

MCUXpresso IDE v11.3.0 (Build 5222)

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MetaClockClock V4 for the Year 2021

I had a few of PCBs left over from the V3 MetaClockClock, and originally I planned to finish a build with them by the end of 2020. But as always: things took a bit longer than expected, so I finally finished it today on the first day of the year 2021.

The build uses the same hardware as in the previous V3, but instead of an ‘artistic’ canvas background I decided for a more natural and wood design:

V4 with Walnut Veneer

V4 with Walnut Veneer

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