Getting Started with Microsoft Azure RTOS (aka ThreadX)

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.

Debugging with ThreadX in MCUXpresso IDE

Debugging with ThreadX in MCUXpresso IDE

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FreeRTOS and Eclipse Indexer for >5K Lines Source Files

Eclipse has a great built-in source code parser and browser (aka ‘Indexer’). It is basically a built-in compiler which parses the source files and assists the user with code completion and navigation help, making Eclipse this awesome productivity tool. On the downside this background parsing could potentially slow down things, and therefore Eclipse has some default settings to prevent this. Unfortunately, the FreeRTOS Kernel ‘tasks.c’ file is above-and-beyond of a ‘sane’ source file and will hit the default limits: as a result the ‘tasks.c’ file is not indexed and things like ‘Open Declaration‘ might not work for the file ‘tasks.c’.

Open Declaration

Open Declaration

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Grouping Eclipse Projects with Working Sets

Typically I have many, many projects listed in the Eclipse Project Explorer, usually more than 100 projects: from example projects, projects on git, lecture module projects, research projects or just some hobby projects I’m working on. With the default Eclipse settings, all these projects are listed in a ‘linear’ list. What I found really useful is the ability to group them into ‘Working Sets‘:

Grouped Projects in Eclipse Project Explorer

Grouped Projects in Eclipse Project Explorer

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Mobile Teacher Tool, Rev 2 by Gerhard

It is always great to see if someone is picking up my work and produces something even better :-). In this case, Gerhard Székely took my DIY Portable Video Conference, Sharing and Teaching Device and created an awesome version of it:

Camera to the front

Camera to the front

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DIY Portable Video Conference, Sharing and Teaching Device

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:

Desk with Communicator

Desk with Communicator C2020

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MCUXpresso SDK Tutorial – using I2C Driver on OKdo E1 board

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:

From the left: Mikroe Weather Click, OKdo E1, Mikroe eInk Click.

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.

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MicroTick (UTICK) Timer Tutorial with OKdo E1 board

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!

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MCUXpresso tutorial: I2C using the Pins/Clocks/Peripherals Config tools and lpcxpresso55s69 SDK

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.

Reading BME280 “ID” register via I2C
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Tutorial: Adding FreeRTOS to where there is no FreeRTOS

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.

Binky on NXP LPC845-BRK Board

Binky on NXP LPC845-BRK Board

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FatFS, MinIni, Shell and FreeRTOS for the NXP K22FN512

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.

FRDM-K22F with SD Card

FRDM-K22F with SD Card

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First experience with OKdo E1 board

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.

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Tutorial: Rename, Copy or Clone Eclipse Projects with MCUXpresso

Especially in a lab or classroom environment it is convenient to start with a template project, and then explore different ways to shape the project for different needs. As for any IDE of this world, this requires an understanding of the inner workings to get it right. So in this article I show how to copy, clone or rename properly an Eclipse ‘template’ project in the MCUXpresso IDE.

Template Project

Template Project

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Tutorial: Maximum Clock Frequency for Kinetis using MCUXpresso Clock Tools

The tinyK22 board with the NXP K22FN512 is a bread-board-friendly small board with a 8 MHz external oscillator:

tinyK22 Board

tinyK22 Board

This tutorial is about how to use the NXP MCUXpresso Clock configuration and configure the board to the maximum clock frequency of 120 MHz. The same steps apply to many other boards, including the FRDM-K22F one.

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Investigating ARM Cortex® M33 core – Dual Core debug tutorial

In last week’s blog I explained that the LPC55S69 microcontroller from NXP has two Cortex® M33 cores, named core0 and core1. There was a lot of theory, and so this week I put it all into practice and show you how to debug 2 cores with MCUXpresso IDE.

Multicore Debugging Interface in MCUXpresso IDE showing 2 different projects
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Investigating ARM Cortex® M33 core – NXP LPC55S69 has *two* M33 cores.

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.

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Investigating ARM Cortex® M33 core – DSP Acceleration 3 (PowerQuad FFT Tutorial)

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.

Data from PowerQuad – 512-point real FFT on 400 Hz input signal with 1200 Hz harmonic
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Investigating ARM Cortex® M33 core – DSP Acceleration 2 (PowerQuad Matrix Engine Tutorial)

Last week I showed you how to use the Coprocessor interface of PowerQuad to calculate (mostly) unary functions. As an example the natural logarithm ln(x) takes just one operand, whilst the floating divide in PowerQuad requires two operands (x1)/(x2). PowerQuad is very efficient accelerating these functions, requiring just 6 clock cycles for the ln(x) and 6 clock cycles for the float (x1)/(x2). In comparison the single-precision floating point unit in Cortex® M4F and M33F requires 13 clock cycles to perform the same float divide.

But there are two ‘sides’ to the PowerQuad:

  • The Coprocessor interface, using ARMv8-M coprocessor instructions;
  • The AHB bus interface, where we address PowerQuad as a peripheral.

So this week… operating the PowerQuad as a peripheral. I’ll show you how to use the PowerQuad SDK driver in MCUXpresso in a new project, and use the Matrix Engine in the PowerQuad to solve simultaneous equations.

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Investigating ARM Cortex® M33 core with TrustZone® – DSP Acceleration 1

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.

ARMv8-M adds many new features to the core architecture, including Co-processor 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.

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Investigating ARM Cortex® M33 core with TrustZone® – In-Application Programming Tutorial

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.

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