Tutorial: Creating and using ROM Libraries with GNU Build Tools

You might never heard about ROM Libraries, and you are probably not alone. Some might thing that this refers to the boot ROM modern MCUs have built in, which is kinda close. But the thing here is about to build your own (possibly constant) ROM library, program it to your device of choice, and then use it from the application running on the device.

So the concept is to have a (fixed, stable) part with code and data on your device, which can be used by a (possibly changing) application: Think about a stable LoRaWAN network stack in the ROM, with a changing application using it: Would that not be cool?

ROM Library Concept

This not only adds flexibility, but as well allows smaller updates, as only a part of the program has to be changed or updated.

The question is: how to create and use such a ROM Library with the normal GNU build tools?

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Installing Processor Expert into MCUXpresso IDE

With the new MCUXpresso versions out, and because it has been a while I showed how to install Processor Expert into Eclipse, here is an update how to do this.

Processor Expert in MCUXpresso IDE
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Using Custom Source File Extensions with Eclipse CDT Gnu Make Builder Projects

One great thing with the Eclipse Gnu Make Builder (aka ‘auto make’ or ‘auto build’) feature: just add source files (*.c, *.cpp, …), and with kind of magic, they all get compiled and linked properly.

But for something easy and convenient: is it hard to use custom file extensions? So what if I want to use a different file extension for my source files, different from the standard ones? Actually Eclipse CDT can do this too, it just takes two settings to recognize, compile and link source files with custom extension.

Custom file extension with Eclipse auto-build
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MCUXpresso IDE 11.5.0

I’m now in the middle of the university fall semester exam season with writing exams and grading student work, and the same time the new semester courses need to be prepared. With the global silicon and board shortage, this will be again a challenge to equip all the labs with the needed infrastructure. The good thing is that there is no shortage on software and tools side of the infrastructure: NXP released last week their new flagship Eclipse based IDE: the MCUXpresso IDE 11.5.0. Time to check it out for the upcoming lectures and classes….

NXP MCUXpresso IDE Version 11.5.0

Spoiler Alert: It has a new view for FreeRTOS lovers, plus new features for energy/power measurements!

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DIY Split-Flap Display

Split-flap displays are electromechanical display devices, which were common in airports or railway stations a few years ago.Unfortunately, most of them are gone and replaced by LED displays. Why not create a DIY version of it?

2×10 Split-Flap Display
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McuOnEclipse Components: 26-Dec-2021 Release

I’m pleased to announce a new release of the McuOnEclipse components, available on SourceForge. This release includes several bug fixes, support for more devices, and updated components like FreeRTOS, MinINI, Percepio Tracealyzer and SEGGER SystemView.

SourceForge

SourceForge

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Key-Value pairs in FLASH Memory: file-system-less minINI

Many embedded systems application need to store some kind of data in a persistent way: calibration values, settings or log information. For a smaller amount of data, using an external memory or file system is an overkill. In many system I’m using minINI to store key-value pars in in a ‘ini-file’ way, but it requires the use of a file system of some kind. minINI is great and efficient, and makes getting and storing data really easy. But for simple cases, a single FLASH memory page or sector is just all what I need. Instead managing that page directly, why not using minINI without a file system?

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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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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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Touch & Build: Auto-Update of Firmware Date and Time

It is very valuable to have a date and time information in the binary. That way for example using a shell I can check the version of the firmware running on a device, or it can be printed on a console or UART as needed.

Firmware Date and Time

Firmware Date and Time

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