Category Archives: Kinetis

Tutorial: MCUXpresso SDK with Linux, Part 1: Installation and Build with Make

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I admit: my work laptop machine is running a Windows 10 OS by default. But this does not prevent me running Linux in a Virtual Machine (VM). Each host platform has its benefits, and I don’t feel biased to one or the other, but I have started using Ubuntu more and more, simply because I have worked more on Embedded Linux projects. While I have used mostly Windows with Eclipse for NXP LPC, Kinetis and i.MX platforms in the past, I started using Ubuntu too from last year with the NXP MCUXpresso SDK. I did not find much documentation about this on the web, so I thought it might be a good idea to write a tutorial about it. So here we go…

Building NXP MCUXpresso SDK on Linux Ubuntu

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Be aware: Floating Point Operations on ARM Cortex-M4F

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My mantra is *not* to use any floating point data types in embedded applications, or at least to avoid them whenever possible: for most applications they are not necessary and can be replaced by fixed point operations. Not only floating point operations have numerical problems, they can lead to performance problems as in the following (simplified) example:

#define NOF  64
static uint32_t samples[NOF];
static float Fsamples[NOF];
float fZeroCurrent = 8.0;

static void ProcessSamples(void) {
  int i;

  for (i=0; i < NOF; i++) {
    Fsamples[i] = samples[i]*3.3/4096.0 - fZeroCurrent;
  }
}
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Remote Debugging with USB based JTAG/SWD Debug Probes

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For some projects it is not possible to have the device under debug available on my desk: the board might be in another room, on another site or in a place where physical access is not possible or even dangerous. In that case an IP-based debug probe (see Debugging ARM Cores with IP based Debug Probes and Eclipse) is very useful: as long as I can access its IP address, that works fine. It is an excellent solution even if the board is moving or rotating: hook it up to a WLAN access point and I still can use it as it would be on my desk.

But what if I have a debug probe only connected to USB? This article shows how to turn a USB debug probe into a IP-based debug solution: that way I can easily debug a board from remote, connected to the network:

IP Based Debugging with USB Debug Probe

IP Based Debugging with USB Debug Probe

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MCUXpresso IDE V10.3.1 available

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On Friday a new release of the Eclipse Oxygen based NXP MCUXpresso IDE V10.3.1 has been made available. The IDE supports MacOS, Linux and Windows 32/64-bit and will be 64-bit only going forward.

MCUXpresso 10.3.1 About Information

MCUXpresso 10.3.1 About Information

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Debugging the Startup Code with Eclipse and GDB

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By default, when debugging an embedded application, the target usually stops at main():

stopped in main

stopped in main

That’s usually fine, but what if I want to debug the code out of reset?

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Tutorial: Changing ARM Cortex Core or Microcontroller in Eclipse CDT Projects

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Sometimes I start a project with an ARM microcontroller, and in the middle of the project I find out that it was a wrong choice at the beginning and I need to switch the microcontroller derivative or even the used ARM core. With little knowledge of the project structure and the files needed, such a switch is not the easiest thing, but definitely possible.

switching cores

switching cores

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Tutorial: Transforming the NXP LPC845-BRK into a CMSIS-DAP Debug Probe

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The NXP LPC845-BRK board is a tiny an inexpensive (sub $6) breakout board. The board includes a CMSIS-DAP (LPC11U35) on-board debug probe which can be used as a debug probe to debug any NXP LPC, Kinetis or i.MX RT device 🙂

LPC845-BRK used to debug robot

LPC845-BRK used to debug a Sumo Battle Robot

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Tutorial: HD44780 Display Driver with NXP MCUXpresso SDK

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In the age of high-resolution graphical LCDs using a character display might look like a bit anachronistic. But these displays provide a lot of value for me as they are robust, available in different shapes and number of lines. And such a character display can be a better solution for an industrial application.

hd44780 display with NXP FRDM-KW41Z Board

hd44780 display with NXP FRDM-KW41Z Board

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FreeRTOS: how to End and Restart the Scheduler

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Most host or desktop systems (say Linux, Mac or Windows) have a normal use case where you start the operating system say in the morning and shut it down in the evening, and then you leave the machine. Embedded Systems are different: they are not attended, and they are supposed to run ‘forever’. Not every embedded system needs to run an OS (or in that world: Real-Time Operating System or RTOS), but the same applies here: after the RTOS is started, it is not intended that it will shutdown and restart. To the extend that you won’t they support the ‘shutdown’ and ‘restart’ functionality at all. In case of gathering coverage information this would be really useful:

coverage information from freertos application

coverage information from FreeRTOS application

In the case of FreeRTOS: what if I really need to shutdown the RTOS and restart it again, as by default this is not supported. This is what this article is about …

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GDB All-Stop and Non-Stop Mode with LinkServer

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GDB supports a mode which allows the GDB debug client to read memory while the target is running. This allows features like ‘live variables’: that way I can see the variables refreshed and changing over time without halting the target. Another functionality which comes with that feature is to check stopped threads or to see all threads in the system.

multiple freertos threads in debug view

multiple FreeRTOS threads in debug view

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