Building a Raspberry Pi UPS and Serial Login Console with tinyK22 (NXP K22FN512)

There are different ways to ruin a Linux system. For the Raspberry Pi which uses a micro SD card as the storage device by default, it comes with two challenges:

  1. Excessive writes to the SD card can wear it out
  2. Sudden power failure during a SD card write can corrupt the file system

For problem one I do I have a mitigation strategy (see “Log2Ram: Extending SD Card Lifetime for Raspberry Pi LoRaWAN Gateway“). Problem two can occur by user error (“you shall not turn it off without a sudo poweroff!”) or with the event of a power outage or black out. So for that problem I wanted to build a UPS for the Raspberry Pi.

Raspberry Pi with UPS System and tinyK22

Raspberry Pi with UPS System and tinyK22

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Tutorial: MCUXpresso SDK with Linux, Part 2: Commandline Debugging with GDB

In “Tutorial: MCUXpresso SDK with Linux, Part 1: Installation and Build with Maked” I used cmake and make to build the SDK application. In this part I’m going to use the command line gdb to debug the application on the board.

Cross-Debugging with GDB

Cross-Debugging with GDB

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Running FreeRTOS on the VEGA RISC-V Board

In “Debugging the RV32M1-VEGA RISC-V with Eclipse and MCUXpresso IDE” I described how to build and debug applications for the VEGA RISC-V board. In this article I describe how to enable FreeRTOS for RISC-V, based on the latest FreeRTOS V10.2.0 release.

Blinky with FreeRTOS on the VEGA RISC-V Board

Blinky with FreeRTOS on the VEGA RISC-V Board

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FreeRTOS: how to End and Restart the Scheduler

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

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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Regaining Debug Access to NXP i.MX RT1064-EVK executing WFI

Working with low power modes can be challenging. It can severely affect debugging capabilities of a microprocessor or microcontroller. I ported a FreeRTOS application using the Tickless Idle Mode to the NXP i.MX RT1064 board, and all of a sudden, the board was unresponsive to any debugger connection. Luckily the board was not really bricked, but it took me while to find a way to recover it. So for when you end up in a situation with a ‘bricked’ i.MX RT1064 board, this article might be helpful for you to recover it.

i.MX RT1064-EVK Board

i.MX RT1064-EVK Board

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New NXP MCUXpresso IDE V10.3.0 Release

Friday this week NXP has released a new version of their flagship IDE: the MCUXpresso IDE V10.3.0. The version number indicates an incremental update from the earlier V10.2.1,  but there are many exciting features and new features which make me switch my lecture material to this new IDE for the next semester.

MCUXpresso IDE V10.3.0

MCUXpresso IDE V10.3.0

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Playing Zork with FreeRTOS on ARM in three different Ways

You might wonder what ‘Zork‘ is? Zork is one of the first and earlist fictive computer games, written around 1977 and 1979, written in MDL on a DEC PDP-10 by members of the MIT Dynamic Modelling group (see https://en.wikipedia.org/wiki/Zork). I believe the first time I have played Zork was around 1984 on a Commodore 64.

Zork

Zork

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McuOnEclipse Components: 30-Sept-2018 Release

I’m pleased to announce a new release of the McuOnEclipse components, available on SourceForge. This release includes several bug fixes, extra support for the NXP S32 Design Studio and SDK and includes FreeRTOS V10.1.1.

SourceForge

SourceForge

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Tutorial: Open-Source Embedded GUI Library LittlevGL with i.MX RT1050-EVK

Most embedded projects need an user input device. For the NXP i.MX RT1050-EVK board I have recently added a 480×272 full color touch LCD (see “Adding a Rocktech Capacitive Touch LCD to the NXP i.MX RT1052 EVK“). I have looked at different commercially available GUI libraries, but none of them really were matching my expectations: either very expensive or closed source, or an overkill for small LCDs and projects. But then I have found LittlevGL: free-of-charge, open source, easy to use, well documented and has everything I need. And it really looks gorgeous 🙂

Hello from LittlevGL

Hello from LittlevGL

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Tutorial: Using Runtime Statistics with Amazon FreeRTOS V10

FreeRTOS includes a nice feature to give me information about how much time every task is spending running on the system:

FreeRTOS Runtime Information

FreeRTOS Runtime Information

This tutorial explains that FreeRTOS Runtime Statistics feature and how it can be turned on and used.

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Using custom FreeRTOS with S32K SDK and OSIF for ARM

In “Tutorial: FreeRTOS 10.0.1 with NXP S32 Design Studio 2018.R1” I showed how to use a custom FreeRTOS with the S32 Design Studio (ARM). The OSIF (OS Interface) provides an operating system and services abstraction for the application which is used by other S32K SDK components:

OSIF in S32K for ARM Eclipse Project

OSIF in S32K for ARM Eclipse Project

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Show FreeRTOS Threads in Eclipse Debug View with SEGGER J-Link and NXP S32 Design Studio

By default, the FreeRTOS threads do not show up with the SEGGER J-Link debug connection in the Eclipse based NXP S32 Design Studio IDE. But don’t worry: Here is how to get it working with SEGGER J-Link debug connection:

FreeRTOS Threads in Eclipse Debug View

FreeRTOS Threads in Eclipse Debug View

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GNU Link Time Optimization finds non-matching Declarations

By default, the GNU compiler (gcc) optimizes each compilation unit (source file) separately. This is effective, but misses the opportunity to optimize across compilation units. Here is where the Link Time Optimization (LTO,  option -flto) can help out: with a global view it can optimize one step further.

The other positive side effect is that the linker can flag possible issues like the one below which are not visible to the compiler alone:

type of '__SP_INIT' does not match original declaration [enabled by default]
Warning by LTO

Warning by LTO

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Tutorial: Understanding and Using FreeRTOS Software Timers

Hardware Timers are essential to most embedded applications: I use them mostly for triggering actions at a given frequency, such as acquiring data from a  sensor. With using an RTOS I can do a similar thing using a task: the task will run with a given frequency and I can periodic work in it. However, using a task might be too much overhead doing this. The good news is that there is a much more efficient way to do this in FreeRTOS with Software Timers. And this is what this tutorial is about: how to use Software Timers with FreeRTOS.

FreeRTOS Software Timers

FreeRTOS Software Timers

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Understanding FreeRTOS Task Stack Usage and Kernel Awareness Information

When using the FreeRTOS Task List in the Eclipse based MCUXpresso IDE, it shows the list of tasks with their stack size used. But with the default FreeRTOS settings it is not able to determine the correct stack size and shows a warning icon:

Warning for Stack Usage

Warning for Stack Usage

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Sneak Preview: DIY SMT Pick & Place Machine with OpenPnP

I apologize: I have not been blogging much in the past weeks :-(. One reason is that I’m working on a DIY SMT/SMD Pick&Place machine which keeps me busy most of my spare time :-). I admit that this project is not finished yet, but now is the time I can give a sneak preview: a SMD/SMT pick and place machine:

Pick&Place Machine

Pick&Place Machine

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Performance and Runtime Analysis with FreeRTOS

One of the great things with the FreeRTOS operating system is that it comes with free performance analysis: It shows me how much time is spent in each task. Best of all: it shows it in a graphical way inside Eclipse too:

FreeRTOS Runtime Information in Eclipse

FreeRTOS Runtime Information in Eclipse

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McuOnEclipse Components: 26-Dec-2017 Release

I’m pleased to announce that a new release of the McuOnEclipse components is available in SourceForge., which is supposed to be the last release for 2017 :-). This release features several smaller bug fixes, the new FreeRTOS V10.0.0 and extended device support.

SourceForge

SourceForge

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New Concept for 2018 Mini Sumo Roboter

Doing Mini Sumo robot competition is really fun, and there is yet another one coming to end the current university semester. For several years we have used our own sumo robot, and this is the one used in the course this year too. But for future and extended events we are exploring a new robot. I proudly present the concept of the next generation sumo robot for the year 2018:

Sumo Robot with Bluetooth module

Sumo Robot with Bluetooth module

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