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 Embedded Software

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Monolithic or not

Tuesday, April 18th, 2017

All my working life, I have had a challenge with explaining to people what I actually do for a job. It all starts with defining what is an embedded system. This is by no means easy. I thought that this might become simpler over time, as embedded systems become even more ubiquitous, but the reverse is true. The definition is getting even fuzzier.

It has reached a point where software engineers do not necessarily know whether they are working on embedded systems or not … (more…)

Get packing

Wednesday, March 15th, 2017

I have frequently made the observation that a key difference between embedded and desktop system programming is variability: every Windows PC is essentially the same, whereas every embedded system is different. There are a number of implications of this variability: tools need to be more sophisticated and flexible; programmers need to be ready to accommodate the specific requirements of their system; standard programming languages are mostly non-ideal for the job.

I have written on a number of occasions about the non-ideal nature of standard programming languages for embedded applications. A specific aspect that can give trouble is control of optimization … (more…)

Embedded tools – the third way

Thursday, February 16th, 2017

A significant factor in getting any job done properly is having the right tools. This is true whether you are building a kitchen, fixing your car or developing embedded software. Of course, it is the last of these that I am interested in here. I have been evangelizing on this topic for years (decades!). The problem is that there is a similarity – arguably superficial – between programming an embedded system and programming a desktop computer. The same (kind of) languages are used and software design techniques are fairly universal. However, there are really some major differences … (more…)

OS migration

Monday, January 16th, 2017

I have often talked about the process that might be applied to the selection of an embedded operating system and I hope that I can provide some guidance. However, developers tend to stick with a specific OS [or, at least, with a particular OS vendor] – recent research suggested that only about 20% of developers anticipated a change of OS for their next project.

I started thinking about why there is this apparently high degree of loyalty … (more…)

Memory signature

Thursday, December 15th, 2016

I am often asked questions about embedded software. Sometimes they are complex; other times they are simple. But frequently, the simplest ones are what leads to an interesting train of thought. The one that set my brain working recently was something like this: “I have some non-volatile memory in my design, which is used to retain specific parameters through power cycling. The first time the device is used, the memory contains garbage and needs to be initialized. When the software starts up, how can I detect that this is the first time it has executed and an initialization sequence needs to be run?”

My first thought was to suggest that simple inspection of the data would show whether it was valid or not. In some applications, that would certainly be true. In others, perfectly valid data could look like a jumble of ones and zeros. There must a be simple, reliable way to make it clear that the memory/data has been initialized … (more…)

Choosing an embedded operating system

Tuesday, November 15th, 2016

I was recently approached for help by a Mentor Graphics customer, who was planning a new project and needed to select an operating system. They wanted guidance with that choice. Of course, one is tempted to say that it does not matter which of our products they chose (as, between them, Nucleus RTOS and Mentor Embedded Linux do cover most possibilities), but I felt they needed something more objective.

There is actually a huge choice. Given that it is decided to purchase an OS, instead of developing something in-house (an expensive option which rarely makes sense), there is the choice between the “heavyweight” OSes, like Windows CE and various flavors of Linux, and around 200 other, mostly real time (RTOS), products. What the customer was after was a simple decision driven process, like a flowchart … (more…)

USB – class drivers

Monday, October 17th, 2016

I have frequently written about various aspects of USB and presented many seminar and conference sessions on the topic. I find it interesting that, considering that USB is such a straightforward technology for most users to utilize, its deployment in devices can be quite challenging.

A particular area of confusion is USB Class Drivers. The word “class” is very overloaded in the software world – it has numerous meanings. And the term “driver” is far from precise. So, it is unsurprising that the subject provokes discussion … (more…)

Device registers in C

Monday, September 19th, 2016

Mentor Graphics has historically been dedicated to providing tools for electronic hardware designers and that still represents a very large proportion of the business. Ever since I was acquired into the company, I have found that the hardware focused guys have a healthy interest in software – embedded software in particular. Often, they are specifically concerned with the boundary between software and hardware … (more…)

Shared code in embedded systems

Monday, August 15th, 2016

A constant challenge I have found, when teaching or mentoring people, is to avoid making assumptions about what they know. I have found that it is so easy to assume that, because something is obvious to me, it is clearly apparent to everyone else. On numerous occasions I have discovered that this not to be the case. Of course, the best response to this realization is not to treat everyone else as stupid, but try to explain something clearly and then listen to the echo back of the explanation.

In developing software – embedded software in particular – there are certain things that are fundamental, particularly around the conservation of resources. More than once I have been surprised by engineers’ inability to focus on this issue … (more…)

C++ reference parameters – the downside

Monday, July 18th, 2016

Something that I have discovered over the years is a great pleasure. When I am giving information – presenting, teaching, writing an article or a blog – it is not necessarily a one-way process. I often receive useful and interesting information back. I have commented that I learn as much from delivering a class as I might from attending one.

I was recently talking about C++ for embedded at a conference and considering some of the features that I felt resulted in better, clearer and more bug-free code. One of these was the option to pass parameters by reference. Then someone explained a drawback of this feature …
(more…)

DAC2017



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