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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Driver and Command Line Shell for Winbond W25Q128 16MByte Serial FLASH Device

Modern microcontroller come with plenty of internal FLASH memory. On the other side, many high performance MCUs as the NXP i.MX RT are ‘flashless’, because the silicon process for high performance cores is not matching the FLASH memory technology, so they are using external serial SPI or Quad-SPI (QSPI) memory instead.

Winbond w25q128 breakout board

Winbond w25q128 Serial Flash Breakout Board

Why not using an external SPI FLASH for a ‘normal’ microcontroller too?

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Driver for VL53L0X Time-Of-Flight (ToF) Sensor and NXP K20DX128

I’m using the VL6180X ToF (Time-of-Flight) sensors successfully in different projects. The VL6180X is great, but only can measure distances up to 20 cm and in ‘extended mode’ up to 60 cm. For a project I need to go beyond that, so the logical choice is the VL53L0X which measures between 30 cm and 100 cm or up to 200 cm. For this project I’m using the VL53L0X breakout board from Adafruit, but similar products are available e.g. from Pololu.

NXP K20dx128 with adafruit vl53l0x tof sensor

NXP K20dx128 with Adafruit VL53LOx tof sensor

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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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Using GDB Server Monitor Commands from Eclipse GDB Console

With Eclipse as IDE it is very easy to debug an application on a board. Still sometimes it is useful to get one level down and control the GDB server directly.

Monitor Flash Download

Monitor Flash Download

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Tutorial: Git with Eclipse

There are things which are game changer in the world of software development: one such event was when I started using a VCS (Version Control System): it changed for me how I keep and store my projects and settings. It even changed the way how I deal with non-software related items like documents or other valuable things: I started storing them in to a VCS too.

EGit with Eclipse
EGit with Eclipse
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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: μCUnit, a Unit Test Framework for Microcontrollers

Unit testing is a common practice for host development. But for embedded development this still seems mostly a ‘blank’ area. Mostly because embedded engineers are not used to unit testing, or because the usual framework for unit testing requires too many resources on an embedded target?

What I have used is the μCUnit framework which is a small and easy to use framework, targeting small microcontroller applications.

uCUnit

uCUnit

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Open Source RISC – Eclipse with RISC-V on the SiFive HiFive1 Board

Open Source software has been around for decades. But open source on hardware especially microcontroller is not much a reality these days. But there is something which might change this: RISC-V is a free and open RISC instruction set architecture and for me it has the potential to replace some of the proprietary architectures currently used. RISC-V is not new, but it gets more and more traction in Academia (no surprise).

I wanted to play with RISC-V for over a year, but finally a week ago I did one of these “hey, let’s buy that board” thing again. Sometimes these boards get on a pile to wait a few weeks or longer to get used, but that one I had to try out immediately :-).

SiFive HiFive1 Board

SiFive HiFive1 Board

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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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