Category Archives: Building

Everything about compiling, assembling and linking.

How to make sure no Dynamic Memory is used

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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

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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 Bare-bare Embedded Projects with CMake, with Eclipse included

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MCU vendors offer SDKs and configuration tools: that’s a good thing, because that way I can get started quickly and get something up and running ideally in a few minutes. But this gets you into a dependency on tools, SDK and configuration tools too: changing later from one MCU to another can be difficult and time consuming. So why not get started with a ‘bare’ project, using general available tools, just with a basic initialization (clocking, startup code, CMSIS), even with the silicon vendor provided IDE and basic support files?

In this case, I show how you easily can do this with CMake, make and Eclipse, without the (direct) need of an SDK.

NXP LPC55S69-EVK with LoRa Shield
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Getting Started: Raspberry Pi Pico RP2040 with Eclipse and J-Link

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In this time where many micro-controllers have 100+ weeks estimated delivery time, it makes sense to look at alternatives. So it is not a surprise that the Raspberry Pi RP2040 gets used more and more in projects. It is not only inexpensive, it is (at least for now) available which makes all the difference. The RP2040 is the first microcontroller from Raspberry Pi: a dual-core ARM Cortex-M0+ running up to 133 MHz, 264 KByte on-Chip RAM and up to 16 MByte external FLASH.

Raspberry Pi Pico with J-Link, with a NXP sensor board

It is a very versatile microcontroller, with a rich eco-system and set of tools. It can be easily used with C/C++ or MicroPython, and the Raspberry Pi Pico board only costs around $5. There are plenty of tutorials out there, for example how to use the Pico board as debug probe to debug another Pico board. While this is great, there is an easy way to use any existing J-Link and Eclipse IDE too, so this is what this article is about.

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Custom ${user} with C/C++ Code Templates

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The Eclipse Editor has a very cool feature named ‘Code Templates’: With such templates files are created with specific pre-filled content. For the templates, variables like ${user} for the user name can be used, see Custom C/C++ Headers with Eclipse:

Eclipse Code Template Editor
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Choosing GNU Compiler Optimizations

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Tool chains like the GNU compiler collection (gcc) have a plethora of options. The probably most important ones are the ones which tell the compiler how to optimize the code. Running out of code space, or the application is not performing well? Then have a look at the compiler optimization levels!

However, which one to select can be a difficult choice. And the result might very well depend on the application and coding style too. So I’ll give you some hints and guidance with an autonomous robot application we use at the Lucerne University for research and education.

INTRO Sumo Robot
INTRO Sumo Robot
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Eyeglasses Case created with CNC and Laser Cutter

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In many cases I prefer wood as material: it has a warm feeling and with its texture it makes things unique and special. For some time I was thinking about creating a wooden case for eyeglasses as a gift. And here is a first version of it:

Oak Wood case for Eyeglasses
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Tutorial: Creating and using ROM Libraries with GNU Build Tools

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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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Include .bin Binary Files in a GNU Linker File

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Sometimes it is needed or desired just to add or link a piece of data or BLOB (Binary Large OBject) to the application. For example I have created a .bin file of my code and constant data, and I need to add it to an application using the linker file. How to do this?

added BLOB to application
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