Should I use that Elevator?

I’m returning from the Embedded World in Nürnberg/Germany. A very busy schedule, a crowed exhibition, and a *lot* of good stuff. IoT (Internet of Things) was everywhere, to the point that I heard from visitors that they do not want to hear it anymore, about it because it so over-used ;-). And it seems that every vendor wants to have its feet in it, without really knowing where it could go. Sounds like in the early days of the ‘internet’, and everyone fears that if he has not ‘IoT’ somewhere, they might miss something.

But the topic here is something completely different: I was staying at a small and inexpensive hotel near the city center. I returned last night around 11pm. I was really tired from the long day, and with a heavy notebook back with me. I was going to enter the elevator to the upper floors, when I saw this signage on the elevator door (sorry the bad image quality):

Elevator Door Sign

Elevator Door Sign

So there I was staying in front of that door, about to press the button, still thinking about the consequences. Not a good sign. Can I take the risk? What would you do?

Happy Elevating 🙂

FreeRTOS V8.0.0 Final Release available as Processor Expert Component

The final FreeRTOS V8.0.0 has been released last week: time to update the Processor Expert component for it, and this time it is really a major release 🙂 : from V7.5.0 to V8.0.0:

FreeRTOS V8.0.0 Processor Expert Component

FreeRTOS V8.0.0 Processor Expert Component

FreeRTOS V8.0.0 comes with many small changes, especially it now includes many of the extra casts I have contributed to avoid compiler warnings. And additionally it has a brand new feature: Event Groups.

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DIY Free Toolchain for Kinetis: Part 10 – Project Creation with GNU ARM Eclipse 2.1.1

As mentioned in Part 9: There is a new GNU ARM Eclipse plugin 2.1.1, and this one makes project creation for Freescale devices easier than ever 🙂

  • Native Kinetis-L project templates for FRDM-KL25Z and FRDM-KL46Z boards
  • Easier than ever project creation for Processor Expert projects
GNU ARM Eclipse 2.1.1

GNU ARM Eclipse 2.1.1

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DIY Free Toolchain for Kinetis: Part 9 – Express Setup in 8 Steps

On Monday the new semester starts, and yet again: we will do a Sumo thing :-). They can choose which tool chain they would like to use to develop their application for the ARM Cortex-M0+ used from Freescale. One option is to create a ‘Do-It-Yourself’ toolchain. Since the start of the series, things have evolved: there is a new GNU ARM tool chain available, Segger has updated their drivers, and most important the GNU ARM Eclipse plugin has been greatly extended to support Freescale parts and Processor Expert. So instead to read through all the previous tutorials, this one is about putting together a free tool chain less than 10 minutes (not counting the time to download around 500 MByte).

DIY Eclipse Toolchain

DIY Eclipse Toolchain

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IoT: FreeRTOS Down to the Micro Amps

University research projects can be a lot fun, and are very challenging the same time. The good thing is that there is always someting new to learn :-).

This week-end I was working on my Internet of Things (IoT) project, based on a Freescale KL15Z and a nRF24L01+ transceiver. In essence it is a wireless data logger. For this, I only can afford a few micro amps consumed by the whole board over an extended period of time. I mean 21 micro amps for running a whole board with sensor, EEPROM, wireless transceiver, operating system and an ARM Cortex-M0+ ready to crunch numbers at 20 MHz 🙂

21 micro amps for wireless sensor node

21 micro amps for wireless sensor node (when not sending)

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CriticalSection Component

I have created and published on GitHub a new component ‘CriticalSection’:

Critical Section Component Methods

Critical Section Component Methods

This component is a wrapper between my components and the problematic current implementation in Processor Expert (see EnterCritical() and ExitCritical(): Why Things are Failing Badly). It uses a flexible approach and uses macros to either use my modified version of EnterCritical() and ExitCritical(), or simply defaults to the original implementation.

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EnterCritical() and ExitCritical(): Why Things are Failing Badly

I have carefully implemented my firmware. It works perfectly for hours, days, months, maybe for years. If there would not be this problem: the firmware crashes sporadically :-(. Yes, I’m using watchdogs to recover, but hey: it is a serious problem. And because it happens only under rare and special conditions, it is hard to track it down or to debug it.

Accessing shared data

Accessing shared data from the main application and from an interrupt

The thing is: these nightmares exist, and they are real and nasty. I’m pushing my students hard on this topic: It is about how to protect critical sections. And what could go wrong. And here is just yet another example: how it can go badly wrong if you are not careful. And it took me a while too to realize where the problem is. It was not a fun ride….

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FRDM with Arduino Ethernet Shield R3, Part 3: Embedded Web Server

This is Part 3 of an ongoing tutorial to use the Arduino Ethernet Shield R3 with a Freescale FRDM-KL25Z board (or any other board you like).

In Part 1 I worked on the SD card, in Part 2 I have added basic network connection. Now time to run a web server with my FRDM-KL25Z :-). With this, I can get access to my board through the network, and the board will host a web page where I can do pretty much everything: showing status, or adding functions to turn on things like an LED 🙂

Web Server with W5100 on FRDM-KL25Z

Web Server with W5100 on FRDM-KL25Z

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DIY Free Toolchain for Kinetis: Part 8 – Processor Expert, Eclipse and GNU ARM Eclipse Plugins

There has been many new releases these days: Freescale released Processor Expert Driver Suite 10.3, and Liviu Ionescu released new GNU ARM Eclipse Plugins with new and updated documentation. So time for me to show how this all comes together 🙂

Processor Expert Driver Suite 10.3 Project with GNU ARM Eclipse Build Tools

Processor Expert Driver Suite 10.3 Project with GNU ARM Eclipse Build Tools

It is now easier than ever before to use the GNU ARM Eclipse plugins and Processor Expert. There are still some manual steps, and this post is about all the details to get it working as smooth as possible.

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