Introduction to Embedded Software Development

What embedded software development is all about, which technologies are used and what comes out of it - all this is usefully compiled here for you.

Software development • UPDATED ON November 15, 2021

Patrick Böllhoff

Author

Embedded software, the code that tells smart machines how to behave and what to do, is just as important as the application software we are used to interacting with every day. And it’s becoming more important every day as more of the devices we find all around us rely on code to function.

Cars, televisions to robot vacuum cleaners, machines used in heavy industry, the robotics in automated warehouses and technology used in surgery operate thanks to embedded software (systems). But who builds embedded software? And are the methodologies, processes and technologies, tools and programming languages used similar to those used by the software development teams creating the application software like websites and apps we are more familiar with?

In this article you will learn what embedded software is, where it is used, how it is developed and commonalities and differences with other kinds of software. In short, this is a beginners’ guide to embedded software.

What is embedded software?

Qian et al., describe embedded software (embedded system software) as “application-specific software designed to perform specific tasks repeatedly without user intervention. With the exception of the simple reset process, once the system is loaded, embedded software is expected to run by itself for a very long time without any damage to the software. Software developers must guarantee the reliability, safety and correctness of the embedded software.”

Simply put, the goal of embedded software is to control and/or manage a hardware device designed for that specific device in order to optimise its specific requirements and maximise its usefulness to the user.

Special features of embedded software

One difference from “normal” software, application software that runs on software (an operating system), is that embedded software is developed in conjunction with a hardware component, similar to firmware, and has few or no interfaces to the outside world. We don’t interact with embedded software other than perhaps while adjusting modes or settings. We see its output in how the hardware device it is integrated with operates.

Embedded software vs Firmware

It is important to briefly explain the difference between embedded software and firmware. Even though the terms are often used as synonyms and there is some overlap, embedded software must be distinguished from firmware. Firmware is usually created at the same time as the development of the hardware component and serves general purposes of the technical system, whereas embedded software is often created at a later time and serves device-specific purposes.

Since embedded software usually adapts to the hardware component and not vice versa,  embedded software developers have only limited processor and computing power at their disposal. However, this also means that the developers of embedded system software must be at least partially familiar with the physical/mechanical conditions.

Probably the most significant difference to application software is the timing behaviour of embedded system software. Due to the interaction between embedded software and hardware components, the embedded software system must work in real time  to be able to execute the time-dependent applications of the device in conformity with the system.

This is the case, for example, with the control of motors. Since their temporal sequences cannot be changed, the embedded system software must be adapted to the temporal behaviour of the technical system (factual system).

According to the 2021 report by Brinksma et al., the correct and secure implementation of reactive or real-time systems such as embedded software is one of the great challenges of IT. This is because, more than ever before, modern society has developed an incredible dependence on such application systems. In addition to embedded system software, these include process control systems as well as telematics systems such as communication services.

Software quality: embedded software

Embedded software is integrated in many everyday devices, but not only in the coffee machine in the office or the WLAN router at home. Embedded systems are also integrated in aeroplanes, machines and in automotive technology and, despite limited processor capacities and computing power, integral to  safety technology (e.g. ABS or airbags). This means that for the safe operation of such technical systems (cars, aircraft, etc.), the embedded software must function safely and reliably, especially in emergency situations. Due to the dependence on such devices, this is one of the great challenges of IT, as already described by “Briksma et. al.”.

In order to meet the requirements for security and reliability there can be no compromise on the quality of embedded software. It’s just as important as the quality of the hardware it interacts with.. There are of course legal security standards that must be met for certain kinds of embedded software.

However, in order to ensure the functional safety of the devices, the  embedded systems development should integrate safety and security frameworks. The features to be considered are often

– Functionality

– Reliability

– Usability

– Efficiency

– Adaptability

– Transferability

At the end of an embedded software development process, the FIT rate (Failure in Time) is checked, which indicates how many errors occur per one billion operating hours. The task of embedded software developers is then to minimise this FIT rate, bringing it as close to zero as possible.

Embedded software developers

Today’s embedded software developers do not need as broad a technical background as those of 20 years ago when strong coding skills and a background in either mechanical or electrical engineering were necessary.But knowledge outside individual programming languages is still necessary to be successful as an embedded software developer. Embedded software developers need to understand the hardware they are working with, yet the trend is to simplify the development process so that embedded software developers will need less and less hardware engineering knowledge.

Due to the strong hardware reference of embedded system software, a  good general grasp of physics and mechanics is still expected. In addition, knowledge of mechanical engineering, electrical engineering and control engineering is still of great value today. As a result, embedded software developers do not only come from a computer science background but are also often former electrical or mechatronics engineers.

Since embedded software can be found in almost all electrical and technical devices today, the profession of embedded software developer is also a very diverse one. Whether in IoT, environmental or Industrie4.0 projects, whether in the automotive industry or in the consumer sector: embedded software developers deal with the development and optimisation of e.g. software-based components as well as microelectronic/mechanical components and their embedded software to solve problems from a wide variety of industrial and economic sectors.

Check out our post on embedded software engineer salaries!

What programming languages are most common for embedded software development?

Programming languages used in embedded software development can be split into two main groups:

• Bare metal programming languages
• Other programming languages useful in embedded software development

Bare metal languages for embedded software development

Bare-metal software is code that doesn’t need an operating system to run but can work directly with the system hardware. As such, a lot of embedded software is coded in:

• C++
• C
• Assembly (just one level removed from binary)
• Rust

Other coding languages used embedded software development

These programming languages are all used in embedded software under particular use-case scenarios, though they are less central to making embedded software systems work:

• Python
• Ruby
• C#

There are also two “hardware design” languages, VHDL and Verilog, which embedded software developers sometimes use to express signals. Code written in these languages is synthesized onto an FPGA (an integrated circuit) so they behave in the way expressed because the layout of the actual circuits are programmable.

Embedded Linux

Embedded Linux isn’t a programming language of course but a family of operating systems designed for embedded devices that need an OS. It runs on processors and is like a diet version of a Linux OS containing only the functionality the embedded system needs. It is often made use of in embedded software environments like:

• IoT devices
• Systems that make use of GUIs like non-smartphone or tablet touch screen devices
• Voice controlled systems that work with natural language processing (NLP)

For more details on programming languages used in embedded software development you can refer to this post by UK-based embedded software development specialists BlueFruit.

The specifics embedded software development

While the embedded software development process is becoming more like standard software development there are still differences.

Can Agile frameworks be used in embedded software development?

A large majority of applications software is built by software development teams working to Agile methodology frameworks like Scrum, Extreme Programming (XP), Adaptive Software Development etc. Does the embedded software development process follow the same Agile frameworks or does it have its own specific methodologies and frameworks?

Application software development methodologies transitioned from linear processes like the Waterfall to Agile approaches as the average software application became more complex and accelerating time to market became more of a priority. Agile’s iterative and ‘release fast’ approach was found to be better suited and resulted in better quality software than Waterfall, whose linear approach meant, especially for big projects, requirements could change before a ‘finished’ product could be released.

Embedded software has also become more sophisticated over the years with the added complexity exposing the weaknesses of a linear Waterfall software development process in the same way application software did several years earlier. The result is that most embedded software development projects now also use Agile frameworks.

Embedded software development teams do, however, have to adopt Agile frameworks to take into account some of the unique challenges they encounter.

Challenges of adapting Agile frameworks to embedded software development

• Target hardware not available at all times to all engineers.
• Huge amounts of configuration combinations which take a long time to comprehensively cover during testing.

These challenges prevent embedded software development teams from working cross-functionally and reinforce silos between:

• Design
• Development
• Test
• Integration

They also make automation hard, which is integral to Agile and CI processes and increase lead times from minutes and hours to days and weeks, which contradicts the Agile requirement of short development cycles between iterations.

Does that mean the embedded software development life cycle is not compatible with Agile processes? Luckily, no. New tools like that marketed in the video below (which also handily explains the challenges of applying Agile frameworks to embedded software development) are helping to remove the challenges that have traditionally led to friction with Agile processes.

Hardware systems can be virtually recreated within a developer’s computer, shared and accessible with the whole team, so embedded software can be developed, tested and run in real time and independently of the target device. It’s all software, just like in applications software development.

Embedded software development tools

Embedded software development tools tend to look and feel outdated compared to those used in application software development where there is a lot of competition and developers have the luxury to be demanding of their tools. As a result, a lot of embedded software developers only use embedded-software specific tools for compiling and debugging with the rest of the work done using standard tools like Visual Studio Code.

However, as mentioned, a new generation of embedded software development tools up to the same standards are application development tools, like target hardware system virtualisation tools, are now coming to market and modernising processes. With embedded software development a quickly growing software development category that’s a trend we can expect to continue.

The future of embedded software

It is apparent that embedded software is now used in almost all sectors and branches of industry and business. Embedded software technology is evolving at breakneck speed and is arguably one of the key drivers of innovation in smart, powerful devices – the applications seem limitless. IoT devices are simply hardware with embedded software that is connected to the internet. According to the paper published in Fior Markets, the global market for embedded software is expected to grow to more than $137 billion annually by 2027 from about $84 billion to date (2020).

As embedded software is an integral part of current innovation themes such as 5G, Internet of Things (IoT) or the autonomous products around robotics and artificial intelligence, the sector is growing exponentially, driven by rising end-user expectations.

As Rob Ferris described in a Feritech Global Limited article published in June 2021, embedded software systems related to machine learning will push the boundaries of manufacturing and production in the next decade.