Category Archives: Testing

Code Quality – Cyclomatic Complexity

Niall Cooling

Director at Feabhas Limited
Co-Founder and Director of Feabhas since 1995.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.

In the standard ISO 26262-6:2011 [1] the term “complexity” appears a number of times, generally in the context of reducing or lowering said complexity.

There are many different ways of defining “complexity”, for example, Fred Brooks, in his 1986 landmark paper, “No Silver Bullet — Essence and Accidents of Software Engineering” asserts that there are two types of complexity; Essential and Accidental. [2]

Rather than getting into esoteric discussion about design complexity, I’d like to focus on code complexity.

Over the years, I […]

Posted in Agile, C/C++ Programming, General, Testing | Tagged , , | Leave a comment

Bugs do matter…(unsurprisingly)

Niall Cooling

Director at Feabhas Limited
Co-Founder and Director of Feabhas since 1995.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.

Welcome to 2018! How did that happen?

Thank you to everyone who attended last week’s webinar on “Measuring Software Quality“, and thank you for the positive feedback, it really does help us shape our future webinars/blogs.

During the talk, I discussed a suggestion by Sally Globe,  along the lines of “Bugs don’t matter”/”Perfect software is the enemy of rapid deployment” as long as you are “Not wrong long”, which came from an initial exchange on Twitter back last year:The caveat was this […]

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An Introduction to Docker for Embedded Developers – Part 4 Reducing Docker Image Size

Niall Cooling

Director at Feabhas Limited
Co-Founder and Director of Feabhas since 1995.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.

In Part 3  we managed to build a Docker image containing the tools required to compile and link C/C++ code destined for our embedded Arm target system. However, we’ve paid little attention to the size of the image. Doing a quick Docker image listing we can see its grown to a whopping 2.14GB:

$ docker image ls
REPOSITORY TAG IMAGE ID […]

Posted in Agile, ARM, C/C++ Programming, Cortex, Testing | Tagged , , , | 3 Comments

An Introduction to Docker for Embedded Developers – Part 3 Cross-Compiling for Cortex-M

Niall Cooling

Director at Feabhas Limited
Co-Founder and Director of Feabhas since 1995.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.

In the previous posting we looked at defining a custom Dockerfile where we can add specific tools (and their dependencies). From that we created a Docker image and this allowed us to build C/C++ code in a Docker container, ensuring a consistent build environment.

So far we have to build all our code using the native GCC toolchain which is part of the base Docker image (gcc:7.2). However, I want to be able to build an image I can download and run […]

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An Introduction to Docker for Embedded Developers – Part 1 Getting Started

Niall Cooling

Director at Feabhas Limited
Co-Founder and Director of Feabhas since 1995.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.

Docker is a relatively new technology, only appearing just over four years ago. The core building blocks have always been part of Unix; but the significant support, Linux containers (LCX), first appeared back in 2008.

Initially Docker was only supported on Linux, but more recently native support for OSX (my development OS of choice) and Windows (albeit Windows 10 Pro) suddenly opens up some interesting workflow choices.

The “What”

So, first, what is Docker? I’m always trying to find the right words here […]

Posted in Agile, Design Issues, Testing | 2 Comments

Agile for Embedded Conference announcement

Whilst there are a number of conferences dedicated to Agile and Scrum, content dedicated to looking at Agile from an embedded systems development perspective is much more scarce and a topic in which many of us are interested.

Although we don’t generally use the Blog to promote events, we think our conference is unique and definitely worth a mention.

3 May, Easthampstead Park, Berkshire

The day offers a pragmatic and practical approach to using Agile in the embedded development environment.

What’s on the agenda?

Using a mix of keynote […]

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goto fail and embedded C Compilers

Niall Cooling

Director at Feabhas Limited
Co-Founder and Director of Feabhas since 1995.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.

I can’t imagine anyone reading this posting hasn’t already read about the Apple “goto fail” bug in SSL. My reaction was one of incredulity; I really couldn’t believe this code could have got into the wild on so many levels.

First we’ve got to consider the testing (or lack thereof) for this codebase. The side effect of the bug was that all SSL certificates passed, even malformed ones. This implies positive testing (i.e. we can demonstrate it works), but no negative testing […]

Posted in ARM, C/C++ Programming, Industry Analysis, Testing | Tagged , , , , , | 5 Comments

Test Driven Development (TDD) with the mbed

Niall Cooling

Director at Feabhas Limited
Co-Founder and Director of Feabhas since 1995.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.

One of the most useful fallout’s from the acceptance of Agile techniques is the use of Test-Driven-Development (TDD) and the growth of associated test frameworks, such as GoogleTest and CppUTest, etc.

I won’t get into the details of TDD here as they are well covered elsewhere (I recommend James Grenning’s book “Test Driven Development for Embedded C” for a good coverage of the subject area), but the principle is

Write a test
Develop enough code to compile and build (but will fail the test)
Write the application code […]

Posted in ARM, C/C++ Programming, CMSIS, Cortex, Testing | 4 Comments

Setting up the Cortex-M3/4 (ARMv7-M) Memory Protection Unit (MPU)

Niall Cooling

Director at Feabhas Limited
Co-Founder and Director of Feabhas since 1995.
Niall has been designing and programming embedded systems for over 30 years. He has worked in different sectors, including aerospace, telecomms, government and banking.
His current interest lie in IoT Security and Agile for Embedded Systems.

An optional part of the ARMv7-M architecture is the support of a Memory Protection Unit (MPU). This is a fairly simplistic device (compared to a fully blow Memory Management Unit (MMU) as found on the Cortex-A family), but if available can be programmed to help capture illegal or dangerous memory accesses.
When first looking at programming the MPU it may seem rather daunting, but in reality it is very straightforward. The added benefit of the ARMv7-M family is the well-defined memory […]

Posted in ARM, C/C++ Programming, CMSIS, Cortex, Testing | Tagged , , , | 8 Comments

I Dream of a Cheeky Missile Launcher

I read a blog post by Matthias Vallentin a while back about getting a USB missile launcher working and thought that a similar gadget would be a nice candidate for the 2012 refresh of our successful EL503 Developing for Embedded Linux course so ordered a nice looking piece of hardware from Amazon – the Thunder Missile Launcher from Dream Cheeky.

Sadly these guys don’t provide Linux drivers and the hardware wasn’t an exact match for the launcher used in Matthias’ article […]

Posted in C/C++ Programming, General, Testing, training | Tagged , , , | 2 Comments