The Colin Walls Blog

This blog is a discussion of embedded software matters - news, comment, technical issues and ideas, along with other passing thoughts about anything that happens to be on my mind.

26 January, 2017

I have some friends, a couple, who are keen tea drinkers – like many English people, of course, including myself. Whilst I am somewhat conventional and like my tea to have some flavor, they are rather odd and seem to want hot water that is barely stained brown. In a café, they will request hot water and a teabag on the side. The teabag is introduced to the water, but not long enough for a strong acquaintanceship to develop – just seconds. They can use a single teabag for 6 or more cups of tea, which is very economic.

I joked recently that what they drink is “homeopathic tea” and this got me thinking about complementary therapies … Read the rest of this entry »

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23 January, 2017

My latest article on has been published. This piece is the fourth installment of the RTOS Revealed series, which will continue to appear through 2017 and beyond. The series will cover every aspect of real time operating systems.

Tasks, the context switch, and interrupts

In this article, I take a further look at tasks and consider how the context switch works and how interrupts may be handled.

I hope that you find the series interesting and look forward to your input by comment or email or via social media.

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19 January, 2017

A while back, I wrote about the Repair Café, which is a monthly event at which a bunch of volunteers endeavor to repair items brought along by members of the public. I have enjoyed being involved with this venture and I am pleased to report on its continued success – we get around 50 “customers” at each session and they report a high level of satisfaction.

However, things have recently taken an interesting turn … Read the rest of this entry »


16 January, 2017

For many years, I would regularly be asked about networking options for embedded systems. Commonly, the query was about real time systems and how they might be connected straightforwardly. Most often, the question was “Can I use Ethernet?” This was an obvious enquiry, as Ethernet is a very well established standard. Also the hardware is widely available and competitively priced and it may be used as a vehicle for TCP/IP etc., which is familiar to many developers. The answer was never totally straightforward … Read the rest of this entry »

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12 January, 2017

I guess that I spend quite a lot of time thinking about Life the Universe and Everything. Starting out on a new year, I always try to be forward looking and positive – even if the state of the world is not so encouraging just now. Overall, I ponder about the fact that we all have a limited time in this world and we should all think about how to use this scarce resource … Read the rest of this entry »

10 January, 2017

Some exciting news today! Every year, publish their Top 10 list of embedded articles. This year I had two entries [#2 and #7], which is a very pleasing start to 2017. It is very interesting that my two articles are both from the RTOS Revealed series, which will be continuing this year, with the next article appearing very soon. It is great to know that they are popular. Perhaps, at the end of this year, I will have the #1 place!

Although I missed #1 this time around, it was great to see that honor going to my colleague at Mentor Graphics, Faizan Khan. Well done Faizan!

9 January, 2017

My latest video blog is now available. I am talking about memory architectures in embedded systems. Not strictly a software issue, but a topic that has a significant impact on embedded software development. You can see the video here or here:

Future video blogs will continue to look at topics of interest to embedded software developers. Suggestions for topics are always welcome via comment, email or social networking.

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5 January, 2017

We decided that we would like to get away for the Christmas and New Year holiday. We had two objectives: find somewhere where Christmas was, if not ignored, a lot lower profile than it is the in UK; get some sunshine. After some deliberation, we chose Sri Lanka [big island, south east of India – formerly called Ceylon]. On vacation, it can be hard to get much impression of the lives of the local people. Tour companies, hotels etc. provide a significant level of insulation, as they endeavor to provide the comforts and mod cons that western visitors expect.

It is always a great opportunity [for me, anyway] to spend time with a “local”, who is happy to tell you something about their way of life. For a few days, we had a driver – I will call him Mr. C. – who, apart from being a good driver on the rather chaotic roads, with an excellent knowledge of his country, liked telling stories. He had many stories and I was taking notes … Read the rest of this entry »

19 December, 2016

As I have been working on the RTOS Revealed series of articles in recent weeks, I have been thinking about the operation and functionality of operating systems. It is a very broad subject – hence the plans for a long series of articles – but I thought that some specific areas might be usefully discussed in this, more compact, context. A topic, that is not often considered, is the question of task identifiers … Read the rest of this entry »

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15 December, 2016

As this is my last “off-topic” posting of 2016 [there will be a techie one next week], I wanted to end the year on a high – of sorts. As I get older, I am increasingly affected – moved, really – by acts of kindness. I am most emotional when the kindness is directed to a stranger and the kind-hearted person has absolutely zero expectation of anything in return. This is a topic that I have discussed before. I am casting my mind back 10 years … Read the rest of this entry »

12 December, 2016

My latest article on has been published. This piece is the third installment of the RTOS Revealed series, which will continue to appear through 2017 and beyond. The series will cover every aspect of real time operating systems.


Tasks and scheduling

In this article, I take a look at tasks, threads and processes and outline their differences. The various types of task scheduling are discussed and some thought is given to the different states that may pertain to a task at a given moment.

You can gain access to the whole series by following this link.

I hope that you find the series interesting and look forward to your input by comment or email or via social media.

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8 December, 2016

I am generally of the opinion that marriage is a Good Thing, as it is a clear step towards the construction of a strong family unit, which is good for society as a whole. My view is shared by most mainline religions and is espoused by most governments, some of which provide fiscal incentives. [In the UK, there is a small benefit for low income couples, but richer people are likely to be fiscally penalized for being married – go figure.] It has been a while since I last considered matters of marriage and weddings for myself – I wrote about it at the time. But I have been contemplating the matter, as some family weddings are scheduled for 2017 … Read the rest of this entry »

1 December, 2016

I have always found the American Thanksgiving holiday rather annoying. I can never remember when it is and nobody gives me any warning. Then, all of a sudden, the world stops for about a week. Having said that, I am totally in favor of having a holiday in the middle of Fall [we have nothing between the end of August and Christmas]. I also admire much of the sentiment around Thanksgiving, as I perceive it. The focus on getting family together and lack of obsession with giving gifts is excellent. Last week, another aspect caught my attention … Read the rest of this entry »

28 November, 2016

ESCNext week, the California ESC event takes place and it is back in San Jose this year. I was planning to be there, as I had a paper accepted. Sadly, I needed to cancel my trip and a colleague will present on my behalf. Here are the details of the paper:

Dynamic Memory Allocation & Fragmentation in C & C++

In C and C++, it can be very convenient to allocate and de-allocate blocks of memory as and when needed. This is certainly standard practice in both languages and almost unavoidable in C++. However, the handling of such dynamic memory can be problematic and inefficient. For desktop applications, where memory is freely available, these difficulties can be ignored. For embedded – generally real time – applications, ignoring the issues is not an option.
Dynamic memory allocation tends to be non-deterministic; the time taken to allocate memory may not be predictable and the memory pool may become fragmented, resulting in unexpected allocation failures. In this session the problems will be outlined in detail and an approach to deterministic dynamic memory allocation detailed.

I am sad to be missing the show, but I hope it goes well. If you would like a copy of my presentation, please contact me via email or social media.

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24 November, 2016

It is my broad philosophy in life to be intolerant of prejudice and bigotry. I endeavor to see everyone as an individual and try not to make any assumptions based on the person’s color, gender, sexual orientation, nationality, religion, social status, body shape, intelligence or financial position. I will not claim to be 100% successful with this goal, but I do try very hard. I am very sympathetic to anyone who experiences abuse as a result of others’ prejudices. However, as I am white, male, heterosexual, British, agnostic, middle class, not fat, fairly smart and solvent, I have almost no experience of being on the receiving end of prejudice. This means that I have difficulty empathizing with a victim of prejudice. But that seems to be changing … Read the rest of this entry »


21 November, 2016

banner_referent_2016The embedded conference season continues and, next week, I will be in Sindelfingen, near Stuttgart in Germany for the ESE Kongress. This is an annual event that I have attended several times over the last few years. There is a small trade show – where some of my colleagues will be manning a stand throughout the week – and multiple streams of presentations … Read the rest of this entry »

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14 November, 2016

Next week is the Embedded Conference Scandinavia [ECS], which takes place in Kista – a suburb of Stockholm, Sweden.

This is the foremost embedded event in the Scandinavian region and I have visited and presented there numerous times. This year I have the privilege of being invited to present 4 papers … Read the rest of this entry »

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10 November, 2016

Like most people, I have a car. I do not mind driving and try to do so in a legal, responsible and courteous manner. I do not particularly enjoy driving, but it gets me from A to B. Some people do get pleasure from driving and I have no problem with that, so long as they do not treat it as a competitive sport. The bit of driving and car ownership that I definitely dislike is parking the darned thing … Read the rest of this entry »

7 November, 2016

My latest article on has been published. This piece is the second installment of a new series, called RTOS Revealed, which will appear from time to time for the rest of this year, into 2017 and beyond. The series will cover every aspect of real time operating systems.

Program structure and real time

In this article I take a look at ways to structure an embedded application and what real time is all about. This leads to the decision making process for utilizing an RTOS or not.

I hope that you find the series interesting and look forward to your input by comment or email or via social media.

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3 November, 2016

Continuing my occasional “Six of the best” series, I want to turn my attention to books – specifically works of fiction. I enjoy reading and always have at least one book on the go. Mostly I would rather read than watch TV. I mostly use my Kindle, which is very convenient. It works well for reading while eating – if I am eating alone. And it is great when traveling.

I read many kinds of books, but do enjoy contemporary fiction. So I have chosen what are probably my favorite six fiction books that I have read in the last few years … Read the rest of this entry »

31 October, 2016

First off, I lay no claim to be an Internet security expert. Maybe because of this, I was quite shocked by the scale and effect of the major DDoS attack that hit the news recently. This attack restricted access to some major websites for Internet users on both sides of the Atlantic. The really interesting aspect of this incident is that the attack was implemented by hijacking large numbers IoT devices … Read the rest of this entry »

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27 October, 2016

I always try to do The Right Thing. I endeavor to be honest and to be considerate and to generally consider the needs and feelings of others. Although I do not subscribe to any recognized religion, I believe that my personal “code” aligns well with most mainstream faiths. I do my best, but I fail all the time; of course I do – I am human. But I feel that it is trying that counts.

I do sometimes question whether trying to be helpful is always the best practice … Read the rest of this entry »

24 October, 2016

ESD-20-years-ARM-TechCon.jpgWorking at Mentor Graphics, as a specialist in embedded software, has always been interesting, but I am often surprised when I meet people at conferences etc. who have no awareness of the company’s involvement in this technology. This ignorance is surprising for two reasons. Firstly, almost all modern electronic systems are embedded systems; hardwired logic is still developed, of course, but that is a minority activity. The second reason for my surprise is that this year Mentor is celebrating 20 years of offering embedded software products and solutions … Read the rest of this entry »

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