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 Embedded Software
Colin Walls
Colin Walls
Colin Walls has over thirty years experience in the electronics industry, largely dedicated to embedded software. A frequent presenter at conferences and seminars and author of numerous technical articles and two books on embedded software, Colin is an embedded software technologist with Mentor … More »

Function parameters

 
November 16th, 2015 by Colin Walls

When you use a function in C/C++ (or most other programming languages) you are likely to pass it some parameters – data which may be processed by the function or give it information on what action is required. For the majority of programmers, outside of the world of embedded software, parameters are just a fact – no real issues. They are likely to be quite uninterested in how parameters are passed and how efficient and secure that process that might be. Embedded developers tend to want details. Efficient code is essential and avoiding possible bugs is always desirable. So, maybe a look at how parameter passing actually works might be useful … Read the rest of Function parameters

Why write code?

 
October 15th, 2015 by Colin Walls

I have a very basic question for you: what do you do and why do you do it? It is quite possible that, if you are reading this, you are an embedded software engineer. It is interesting to consider what that job actually entails. First off, how would you reply to the “What do you do?” question from someone you meet in a pub/bar? You would probably say Software Engineer, but they might ask you to expand on that. [Actually, such a reply can be a complete conversation killer. You might be better to reply with Airline Pilot or some such. Just invent a new persona and have some fun.]

It is easy to think of an embedded software engineer’s job as being all about writing code that programs a device to behave in a particular way. But that is a long way from the whole story… Read the rest of Why write code?

Electronics for the sick

 
September 16th, 2015 by Colin Walls

I have always for medical electronics interesting. Part of the reason for my interest stems from an occasional feeling that so much of the electronics around me is ultimately pointless. Many Mentor Embedded customers are making consumer devices, cell phones and other gadgets. Do we really need all of these? Aren’t they really just toys – harmless toys, but toys nevertheless? (Except for my iPad, of course, which is a positive influence on my productivity and overall wellbeing.) Worse still, some customers are actually making weapons and they are not harmless at all!

However, we have many customers who make medical devices. I only have to look at a medical instrument and I have a warm feeling inside that maybe electronics can do some real good. The other aspect of medical instrumentation, that I find intriguing, is the extent to which its implementation clearly tracks the latest trends in embedded system development … Read the rest of Electronics for the sick

When compilers do magic

 
August 17th, 2015 by Colin Walls

What is a compiler? Ask an average engineer and you will get an answer something like: “A software tool that translates high level language code into assembly language or machine code.” Although this definition is not incorrect, it is rather incomplete and out of date – so 1970s. A better way to think of a compiler is: “A software tool that translates an algorithm described in a high level language code into a functionally identical algorithm expressed in assembly language or machine code.” More words, yes, but a more precise definition.

The implications of this definition go beyond placating a pedant like me. It leads to a greater understanding of code generation – and just how good a job a modern compiler can do – and the effect upon debugging the compiled code …

Read the rest of When compilers do magic

How did I get into this?

 
July 14th, 2015 by Colin Walls

I often get emails from students asking me how to get started in a career in embedded software. I have to assume that they think that this is a path to a well-paid job and a corresponding glamorous lifestyle. I would hate to disillusion someone who is just setting out on life. I guess that I had great expectations too.

I am never able to give detailed advice on what to do and just comment that embedded software engineers actually come in several flavors. At one extreme, they are engineers with a deep knowledge of hardware and only do a bit of software when necessary; such skills are ideal for developing drivers and other low level code. At the other extreme, there are programmers who have no idea about embedded systems, but are focused on the application domain; their skill set is not very different from a software engineer working on applications for Windows or Linux. And, in the middle, are guys who understand real time behavior and real time operating systems.

Read the rest of How did I get into this?

AMP vs SMP

 
June 16th, 2015 by Colin Walls

It is becoming common for embedded designs to incorporate more than one CPU – maybe multiple cores on a chip or multiple chips on a board or any combination of these. Indeed, it has been suggested that it will soon be the norm to build systems that way.

The use of multiple cores has spawned various technologies and, of course, much terminology and jargon. When new technical terms and acronyms appear, there is inevitable misuse and misunderstanding. This seems to be the case with AMP and SMP, so maybe I can set the record straight … Read the rest of AMP vs SMP

Using an MMU

 
May 20th, 2015 by Colin Walls

Many microprocessors and microcontrollers incorporate a memory management unit (MMU) or have one available as an option. Equally, there are some devices that have no MMU support and many systems are built without one anyway. Having met some engineers recently, who could not conceive of the idea of no MMU, clarification may be necessary … Read the rest of Using an MMU

OS influence on power consumption

 
April 16th, 2015 by Colin Walls

Power consumption is an issue. With portable devices this affects battery life. [I am irritated by the short intervals between necessary charging sessions with my smartphone, for example.] With mains powered equipment, power consumption is also a concern for environmental reasons. The matter of power has always been seen as a “hardware issue”, but, of late, there has been an increasing interest in the role of software … Read the rest of OS influence on power consumption

Vintage multi-core – the IPC

 
March 16th, 2015 by Colin Walls

Last time, I wrote about a “multi-core” project that I was working on 30 years ago. To be fair, it was actually “multi-CPU” rather than “multi-core”, but many of the challenges were similar, as was the initial design decision to take the approach of distributing the processing capacity. It is interesting to draw a comparison between the system that we were developing all those years ago and modern ideas for multi-core design. A common approach is to use one core for real time functionality (running an RTOS like Nucleus perhaps) and another for non-real-time activity (maybe running Android or Linux).

Using multiple CPUs (or cores) presents a variety of challenges. One is the division of labor, which was reasonably straightforward in this case. Another is communication between the processors … Read the rest of Vintage multi-core – the IPC

Vintage multi-core – introduction

 
February 16th, 2015 by Colin Walls

Sometimes I think that there is nothing truly new in the world. With technology, it is often a question of the time being right. It occurred to me that the current enthusiasm for multi-core designs is really nothing new. I browsed some of the literature and titles like “Multi-core is here now” have been appearing for at least 5 years. But it goes back further still. I was working on a multi-core system in 1980 … Read the rest of Vintage multi-core – introduction

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