How to make sure no Dynamic Memory is used

In many embedded applications, it is mandatory that memory allocation is static and not dynamic. Means that no calls to things like malloc() or free() shall be used in the application, because they might fail at runtime (out of memory, heap fragmentation).

But when linking with 3rd party libraries or even with the C/C++ standard libraries, how to ensure no dynamic memory is used? The problem can occur as well for C++ objects, or a simple call to printf() which internally requires some dynamic memory allocated.

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Shut Down C++ Embedded Systems with Calling the global Destructors

If using C++ on an embedded target, you depend on the constructors for global objects being called by the startup code. While in many cases an embedded system won’t stop, so you don’t need to call the global C++ destructors, this is still something to consider for a proper shutdown.

Calling OOP Destructors after leaving main()
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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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Silicon Shortage and Semihosting with NXP MCUXpresso SDK on FRDM-KE02Z

The silicon shortage is still going on. While the NXP Kinetis KE devices might not be my first choice, they still seem to be available, in at least in lower quantities. This has been recognized by others, as I’m getting more and more questions and requests for the KE and KV family. This is why I un-dusted my old FRDM-KE02Z to be used with the latest MCUXpresso SDK and IDE.

FRDM-KE02Z Board

And in case you want to use that board or device with semihosting, I have you covered.

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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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LoRaWAN with NXP LPC55S16 and ARM Cortex-M33

LoRaWAN is getting more an more popular, both for terrestrial and increasingly with low-orbit satellite systems. The ‘Long Range’ in ‘LoRa’ makes it an ideal solution for low-power and low data rate applications. For a university research project we selected the Semtech SX1261/62 transceiver together with the NXP LPC55S16 mikrocontroller. Because the board used for that project is not available for the public (yet), I share here how you can run the LoRaWAN stack with the NXP LPC55S16-EVK.

LoRaWAN with Semtech SX126x and NXP LPC55S16
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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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Doubling the performance of NXP LPC845 with improved Flash Access Time

For more than two years I’m using the NXP LPC845 in my university courses. Beside of that it is used in many projects. First, because the LPC845-BRK board is small, breadboard friendly and inexpensive. Second, for many small projects that Cortex-M0+ provides just the right amount of processing power and memory.

NXP LPC845-BRK Board
NXP LPC845-BRK Board

If you search for ‘LPC845’ on my blog, you will find many articles about it. We are using the LPC845 in a research project, and one developer asked me why the LPC845 seems to run slower than expected. And I was sure that I wrote already an article about this, but to my disappointment: even Google did not find it? So complete this unfortunate gap, here is it: how to optimize the LPC845 and running it at full speed, with the hand-brake released.

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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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