COVID-19 is by far not over, and in Switzerland the infection rate is going up again (2nd wave?). During the spring 2020 semester university lock-down we moved pretty much everything to a ‘distance learning’ setup. With that experience and with the request to prepare for the fall semester, I have constructed a DIY conference and teaching device which should make things simpler and easier: a combination of video camera, speaker phone and a muting device:
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
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
I want to share with you a little embedded trick that I use to improve the reliability of my code. And in addition to improving reliability, the technique can be used to schedule any event to occur ‘sometime in the future’. It uses the MicroTick (UTICK) timer found on the NXP LPC55S69 microcontroller, and could be applied to any device with a simple timer.
The MicroTick timer is an elegant, thing of beauty. But there is not a driver example built into the lpcxpresso55s69 SDK, and I believe that the timer is not widely used. That means we need a tutorial!Continue reading
This is a follow-up article of my earlier project presented in “FatFS, MinIni, Shell and FreeRTOS for the NXP K22FN512“. I wanted to extend it with a USB MSD (memory stick) device: The USB storage device gets automatically mounted, and depending on a configuration (.ini) file on the memory device I can perform various actions, for example automatically copy data from the SD card to the USB device. For example the system logs data, and to get the data I insert the memory stick, it copies the data on it and automatically unmounts it, and I can remove the memory stick.
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.
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.
Right before Christmas 2019, NXP has released a new version of the MCUXpresso IDE, the version 11.1.0. This gave me time to explore it over the Christmas/New-Year break and evaluate it for the next university semester. There are several new features which will make my labs using it easier, so I plan to get the course material updated for it.
After the break you will find the highlights …
When using an RTOS like FreeRTOS, sooner or later you have to ask the question: how much time is spent in each task? The Eclipse based MCUXpresso IDE has a nice view showing exactly this kind of information:
For FreeRTOS (or that Task List view) to show that very useful information, the developer has to provide a helping hand so the RTOS can collect this information. This article shows how this can be done on an ARM Cortex-M.
Human since 1982 claims
“Human since 1982 have the copyright to works displaying digital time using a grid arrangement of analog clocks…”
I’m not a lawyer, but without obligations (imho) I have removed the content.
Thanks for understanding,
For this last blog in the series Investigating ARM Cortex® M33 core I decided to explore the expansion features of the LPC55S69-EVK. This board has three expansion ports (PMOD, Arduino Duo, Mikroe click) and I picked the Mikroe expansion port. Why? Only because I had good experience with these boards with the Hexiwear project.
And because I have been doing some work this month with AWS IOT I wanted to get my LPC55S69-EVK onto my office WiFi network for the Christmas holidays. I know that the MCUXpresso SDK for lpcxpresso55s69 version 2.6.3 has a built-in WiFi example named qca_demo, and so that is what I am investigating today.
That WiFi example supports three WiFi shield boards, and I picked the Mikroe WiFi 10 click board. It’s part number MIKROE-3432 and available from all of the usual catalogue distributors.Continue reading
Throughout this series I’ve been using the LPC55S69 microcontroller from NXP as a platform to investigate the ARM Cortex® M33 core. NXP designed the LPC55S69 with two Cortex M33 cores and so this week I’m investigating these in more detail.
You’ll remember that when ARM launch a processor core it will have a number of optional features. This is shown very clearly on the LPC55S69. The 150 MHz primary core – cpu0 – is a full implementation of Cortex® M33 and includes the optional components FPU, MPU, DSP, ITM and the TrustZone® features.Continue reading
I’ve always felt that the Fourier Transform (and in particular the embedded implementation Fast Fourier Transform) is the GOAT* of the DSP algorithms. The ability to convert a time-domain signal into a frequency-domain signal is invaluable in applications as diverse as audio processing, medical electrocardiographs (ECGs) and speech recognition.
So this week I’ll show you how to use the Transform engine in the PowerQuad on LPC55S69 to calculate a 512-point FFT. All of the difficult steps are very easily managed and the PowerQuad does all of the very heavy lifting.Continue reading
If you ask your colleagues about ARM Cortex® M33 core, they’ll most likely remember that the ARMv8-M architecture adds the (optional!) TrustZone® security extension. But one, overlooked but significant new feature in ARMv8-M is the new coprocessor interface.
With the LPC55S69 microcontroller, NXP decided to add an extremely powerful DSP Accelerator onto this coprocessor interface, named PowerQuad. In this week’s video series I’m investigating the PowerQuad, and the functions that it provides.Continue reading
Last week I investigated the In-System Programming feature in the boot ROM of the LPC55S69. Using the command-line program blhost I was able to erase the flash and download simple LED blinky programs. Of course, the functions that erase and program the flash are present in the boot ROM.
Wouldn’t it be great if we could call those program and erase functions from our own software running on the LPC55S69?
Of course, we can. This is the NXP feature In-Application Programming, and this week I’ll show you how to interface to the Flash Driver in the boot ROM from software. Since the program and erase functions are running from ROM, this avoids the normal considerations about using flash for non-volatile storage.Continue reading