Having visibility and insights into a running system is highly valuable or critical: not only for optimizations but as well to verify the system design and behavior. In Getting Started with Microsoft Azure RTOS (aka ThreadX) I showed how to quickly run Azure RTOS. This article is about getting trace out of an ThreadX application and show it in TraceX.
Reentrancy is an attribute of a piece of code and basically means it can re-entered by another execution flow, for example by an interrupt or by another task or thread. This is an important concept and still a lot of code ‘in the wild’ does violate reentrancy. As a result the application crashes immediately in the best case. Worse it crashes randomly or even worse it behaves incorrectly 😦 .
Reentrancy is always a concern if using standard library functions, including printf() or malloc(). FreeRTOS offers a reentrant wrapper to the standard malloc() and free() (Memory Scheme 3)
If you are a regular reader of my articles, you probably know that I’m using FreeRTOS in most of my applications, for obvious reasons. But clearly this is not the only RTOS out there. After Microsoft had acquired Express Logic back in April 2019 things kept quite for a while. To me the crown jewel of Express Logic is the ThreadX RTOS. But recently Microsoft is pushing more and more the ‘Azure Sphere’ and trying to monetize the ‘IoT’ (I apologize for mentioning that overused acronym) application space and providing it now free for devices from selected partners which includes NXP now.
If having a boot loader running on a micro-controller, it is very useful if both the boot loader and the loaded application can be debugged together:
‘Dark’ or ‘Black’ themes are on vogue: some love it, some do not care. The good thing is that we all have a choice. Things are getting improved on the host OS (Windows/Linux) side, but the challenge is still on the application side, but things are getting better. This is true for the Eclipse based IDEs too, with the NXP MCUXpresso IDE V11.2.1 just recently released: it comes with improved Dark Theme support:
I have started the semester and labs using the MCUXpresso IDE V11.2.0 which has been available from July this year. The past week I received the notification that the update V11.2.1 is available: time to check it out….
Amazon has released in the past week the FreeRTOS version V10.4.0. Time to upgrade, actually the most recent version 10.4.1! The same time the SEGGER SystemView V3.12 was released back in April this year. No surprise: with the FreeRTOS changes they don’t work out of the box: but no worries, I have you covered and applied all the needed patches and changes to have them working again together: the latest FreeRTOS v10.4.x with Segger SystemView v3.12:
At the university the end of a semester means that you have to get ready for the next semester. I always tend to use the latest and greatest tools for the labs. This week I received the notification that a new version of the Eclipse based MCUXpresso IDE is available, time to check it out for the next semester.
I have continued to explore my two hobbies (embedded systems, and Talking About The Weather) during these weeks of lock-down. I have finally got to the point that my Weather Station project can sit on the window shelf of my office, and show me the temperature, humidity and atmospheric pressure on the attached eInk display.
In this blog I’m going to focus on driving that display.Continue reading
Creating a new project with Eclipse for a microcontroller these days is fairly easy, and I have the choice if I want to start the project with C or C++:
Still the embedded microcontroller world is dominated by C and not C++. So while it is easy to start with a C++ project, most vendor provided example or tutorial project are C projects. So how can I transform such project to C++?
In an earlier tutorial I introduced using I2C with the NXP LPC55S69 on OKdo E1 board to read a Bosch BME280 environmental sensor on a Mikroe Weather Click board. The MCUXpresso Clocks, Pins and Peripheral Config tools were used to get it running. It’s all for my Weather Station project that I’ve been working on during these months of lockdown. It is starting to take shape – as you can see from the photograph:
Now I really need to start reading and writing to the BME280 sensor, and that means using the I2C driver in the lpcxpresso55s69 SDK. And so this week I’ll provide a forensic examination of the most commonly-used I2C function call.Continue reading
The NMI is a special interrupt on ARM Cortex-M architecture: as the name indicates, it cannot be ‘masked’ by the usual ‘disable interrupts’ flags (PRIMASK, BASEPRI), similar to the Reset signal.
Dealing with the reset signal is kind of obvious, and most designs and boards have it routed to a reset button or similar. The NMI is less obvious if you don’t pay attention to it: most ARM-Cortex implementations and boards have the NMI signal routed to a pin and are ‘hiding’ it in the schematics behind a normal GPIO pin or port: if you don’t pay attention to the NMI functionality, the board might not work as intended.
An essential tool especially developing larger applications or distributed firmware is to use logging. This article presents an open source logging framework I’m using. It is small and easy to use and can log to a console, to a file on the host or even to a file on an embedded file system as FatFS.
I selected the Bosch BME280 environmental sensor as the heart of my OKdo E1-based weather station. It is convenient to use, and I can prototype with the Mikroe Weather Click board MIKROE-1978. But the sensor is accessed over I2C, and that is my least favourite of the communication interfaces. In this short tutorial, I show you how the MCUXpresso Config tools (Pins, Clocks, Peripherals) are used to set up the I2C driver from the MCUXpresso lpcxpresso55S69 SDK. And very quickly, I am able to communicate with the BME280 sensor.Continue reading
FreeRTOS is pretty much everywhere because it is so simple and universal, and it runs from the smallest to the biggest systems. But it still might be that for the microcontroller device you have selected there is no example or SDK support for it from your vendor of choice. In that case: no problem: I show how you could easily add FreeRTOS plus many more goodies to it.
I’m using the NXP Kinetis K22FN512 in many projects, either with the FRDM-K22F or on the tinyK22: with 120 MHz, 512 KByte FLASH and 128 KByte it has plenty of horsepower for many projects. The other positive thing is that it is supported by the NXP MCUXpresso IDE and SDK. I have now created an example which can be used as base for your own project, featuring FreeRTOS, FatFS, MinIni and a command line shell.
This week I’m sharing my experience “getting started” with the OKdo E1 board. This board, featuring the NXP LPC55S69 150 MHz, dual Cortex M33 core microcontroller was a joy to use. OKdo have provided an online Getting Started guide, and I’ve field-tested this for you. My video tutorial recorded as I follow the guide is less than 7 minutes long… it may take you a little longer if you need to download MCUXpresso IDE or the lpcxpresso55s69 Software Development Kit (SDK) but I am confident that you will quickly have the board up-and-running.Continue reading
I will always take the same approach when I receive a new embedded board: firstly I want to see how quickly I can get it up-and-running, then I want to see what it does “out-of-the-box” and finally I want to find out if the board is “useful”. Does it have some features that will inspire me for new projects??
The NXP LPC55S16-EVK has some great features – CAN-FD, dual USB and a high performance Cortex M33 microcontroller, running at 150 MHz. I have an idea to use the LPC55xx series as the basis for a Weather Station. But this is only feasible if the chip has a low power consumption and can run for weeks on a small battery.
Time to run some test code and get my digital multimeter out…Continue reading
FreeRTOS has many cool features, and one is that it can report the CPU percentage spent in each task. The downside is that to get this kind of information some extra work is needed. In this article I show how to do this for the NXP i.MX1064.