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Embedded systems have been with us for ages. Read on to learn what they are, some safety concerns of embedded systems, and how proper testing can help make them safe and secure.
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Embedded systems are the dedicated computing engines behind modern products and infrastructure, enabling devices to sense, process, and act on the physical world with speed and reliability.
Embedded systems are microprocessor-based computer systems, usually built into a system or product, that have a dedicated operational role. In other words, embedded systems are the hidden "smarts" behind all the devices we use, the cars we drive, the planes we fly on, and the trains we ride in.
Rather than being made of separate components like desktop computers, servers, and other similar domains of computing, embedded systems are enclosed into products and include integral hardware and software.
Embedded systems power devices across nearly every industry. They’re not optional enhancements—they’re the operational core of modern technology. Here are a few examples.
Embedded systems are the invisible intelligence inside the products and infrastructure we rely on every day. In consumer electronics, these systems power smartphones, smart TVs, wearables, and smart home devices, quietly managing power consumption, wireless communication, sensors, and user interaction. Companies like Apple Inc. design products that contain dozens of specialized embedded controllers working together to deliver seamless performance.
In the automotive world, embedded systems are even more critical. Modern vehicles from manufacturers such as Waymo LLC contain networks of electronic control units (ECUs) that manage autonomous driving, braking, steering, battery performance, airbag deployment, and advanced driver assistance systems. These systems must operate flawlessly in real time, often under extreme environmental conditions.
Healthcare provides another powerful example. Devices developed by companies like Medtronic, including pacemakers, insulin pumps, and patient monitoring systems, depend on embedded software that must be both precise and reliable. A malfunction is not an inconvenience—it can be life-threatening.
In industrial and transportation sectors, embedded systems run factory automation, robotics, railway signaling, and avionics. Organizations such as Siemens AG deploy embedded controllers to manage everything from power grids to manufacturing lines. Aircraft built by Boeing rely on redundant embedded flight control computers to maintain safety at 35,000 feet.
What sets embedded systems apart from general-purpose computers? Focus.
Embedded systems are designed to perform a specific, dedicated function. Nothing more, nothing less. Unlike a desktop computer that runs countless applications, an embedded controller in a braking system exists for one mission: detect conditions and respond instantly. That singular purpose drives every architectural decision.
Embedded systems also operate under strict resource constraints. They often run on limited processing power, minimal memory, and tight energy budgets. Engineers must write highly efficient code and carefully balance performance with hardware limitations. Optimization is not a luxury. It’s a requirement.
Timing is another defining characteristic. Many embedded systems are real-time systems, meaning they must respond within precise deadlines. In safety-critical environments, such as automotive braking, medical devices, or avionics, missing a timing window can result in system failure. Correctness is measured not just by what the system does, but when it does it.
Reliability and determinism further distinguish embedded systems. These systems frequently operate for years without rebooting, often in harsh conditions. They must behave predictably, tolerate faults, and maintain stability over long lifecycles. Unlike consumer software that can be patched frequently, embedded systems are commonly deployed in environments where updates are difficult, expensive, or highly regulated.
Finally, embedded systems are tightly integrated with hardware. They directly control sensors, actuators, motors, and communication interfaces. Hardware and software are co-designed, optimized together, and validated as a unified system. This deep integration and the high stakes associated with failure are what fundamentally separate embedded systems from general-purpose computing.
What’s interesting about embedded systems is the breadth of applications. They range from small controllers in smart home devices to avionics systems in airplanes to large networking switches that make up our telecommunication networks. This also makes them challenging to design and develop. The constraints of the intended product impact the performance envelope of the embedded hardware and software.
Embedded systems are ubiquitous but relatively unknown to most consumers. Modern automobiles have up to 100 million lines of code in them and most of that is not in the infotainment system. So much of a modern car’s software and hardware is in the various microcontrollers and engine control units that control and monitor modern features.
Embedded systems consist of hardware and software as mentioned above. They’re often used in applications that require both sensing something physical in the environment and controlling something in response.
A simple example is an HVAC system with an embedded thermostat controller. Such a system would sense the room temperature and actuate either the heating or air conditioning. It might need some form of communication via a network interface and display temperature on an LCD screen (human/machine interface or HMI.)
Such systems are often called "real time" or "event driven" since they must react in a timely fashion to real world events. Depending on the type and criticality of the application, reacting to events at a specific time is important. Safety-critical systems like antilock brakes (ABS) in a car must react within milliseconds. Such systems are referred to as "hard real time" meaning they must meet required deadlines or a failure has occurred. Systems with looser deadlines are referred to as "soft real time". In most of these cases, these systems run on top of some sort of real time operating system (RTOS).
Here’s a simple example of embedded system architecture:
Also unique to embedded systems is the use of a microcontroller architecture. Unlike desktop or server systems, microcontrollers usually have all the RAM, ROM, and I/O on a single chip. These controllers often have the required I/O capabilities to interact with sensors and actuators and integrate with network and other communication devices.
At the most fundamental level, many embedded systems use a simple architecture in which a single program runs continuously in an infinite loop. Often called a super loop, this design repeatedly reads inputs, processes data, updates outputs, and then starts over.
Because there’s no operating system or task scheduling overhead, the behavior is highly predictable and easy to verify. This approach is common in small devices like basic sensors and low-cost controllers, where the functionality is limited, and timing requirements are modest.
A closely related pattern is the control-loop architecture, widely used in systems that must continuously regulate physical processes.
In this model, the software repeatedly measures a system state, such as temperature, speed, or position, compares it to a desired value, and adjusts actuators to minimize the difference. Examples include thermostat controllers, motor speed regulators, and simple industrial automation components.
The appeal of control-loop designs lies in their:
However, these architectures also have clear limitations.
Because all operations execute sequentially, long-running tasks can delay time-sensitive functions, and responsiveness to unexpected events may be poor.
As system complexity grows, such as when multiple sensors, communication interfaces, or user interactions must be handled simultaneously, the super loop becomes difficult to maintain and scale. For this reason, simple loop-based designs are best suited to small, well-defined applications with minimal concurrency requirements.
When embedded systems must react quickly to external events, interrupt-driven architectures provide a more responsive alternative. Instead of waiting for the main program loop to check for changes, hardware signals can interrupt normal execution and trigger specialized routines immediately.
This mechanism allows the system to respond to time-critical inputs such as button presses, sensor thresholds, communication arrivals, or fault conditions. By handling urgent tasks asynchronously, interrupt-driven designs significantly improve responsiveness without requiring a full operating system.
Multitasking architectures extend this concept further by allowing multiple software tasks to execute seemingly at the same time. In many embedded systems, this is achieved through:
Tasks may handle different responsibilities, such as sensor processing, user interface updates, data logging, and network communication, while sharing the same processor. This structure improves modularity and scalability, making it easier to add features without destabilizing the entire system.
These architectures are typically preferred when systems must manage concurrent activities, maintain responsiveness, or support communication with external devices.
Automotive control networks, medical monitoring equipment, and connected consumer products frequently rely on interrupt-driven or multitasking designs. While more complex than simple loops, they provide a practical balance between performance, flexibility, and resource usage for mid-range embedded applications.
For sophisticated embedded systems, kernel-based architectures introduce a formal operating environment that manages hardware resources and software tasks. At the core is often a real-time operating system (RTOS), which provides:
RTOS platforms such as VxWorks, QNX, RTLinux, and ThreadX are widely used in applications that demand deterministic timing, high reliability, and structured concurrency. By delegating low-level management to the kernel, developers can focus on application logic while maintaining predictable real-time behavior.
Layered architectures complement kernel-based designs by organizing software into hierarchical levels, each with clearly defined responsibilities.
This separation of concerns improves maintainability, portability, and testability, particularly in long-lived systems where components may evolve independently.
The benefits of these more advanced architectures become evident in large-scale or safety-critical applications such as avionics, advanced automotive platforms, medical devices, rail, industrial automation systems, and telecommunications infrastructure.
They support complex functionality, fault isolation, security mechanisms, and long-term maintainability—capabilities that simpler architectures cannot easily provide. While they require greater development effort and system resources, kernel-based and layered approaches enable the reliability, scalability, and sophistication expected of modern embedded systems.
Embedded systems run on hardware designed to meet the limitations of the product they’re used in. The hardware is often specified to meet targets for business (for example, cost) and technical. These products can number in the millions of units and operate for decades, implying the need for both hardware and software reliability and quality.
Common constraints on embedded system hardware are:
These constraints limit the performance and complexity of the application that the hardware can support. In turn, this increases the design and development challenges, especially when trying to integrate more features.
Embedded system hardware constraints are driven by business requirements that often impact the profitability of the end product.
Target hardware examples include small microcontrollers like:
Most of the engineering effort goes into the software of embedded systems. In fact, most manufacturers need a software group to develop the applications embedded in their products. Jokingly, CEOs of these companies jest, "We are a software company masquerading as a widget manufacturer."
The reality is that software has become the key area of differentiation and innovation in many markets, including companies whose main product is not software.
Just as with hardware, the software complexity depends on the intended application which can vary greatly. However, there are three major categories that most embedded software fits into:
These applications are usually on 8 and 16-bit microcontrollers with no formal operating systems, also known as bare metal. The applications are usually controlling a single subsystem based on a few sensors. They may not be connected to a network and might be operating autonomously. High-level control is elsewhere, such as with a supervisory control and data acquisition (SCADA) system, usually with much more complex hardware and software.
These systems often use commercial or open source embedded operating systems which are frequently real-time as well (RTOS.) These operating systems provide the necessary hardware abstraction, multiprocessing, multithreading, network, and interface libraries. Examples include FreeRTOS, VxWorks, and QNX, and in some cases, embedded Linux. Applications can vary from hard real-time, safety-critical applications such as airplane avionics to wireless routers and HVAC systems.
Usually, the hardware is 32-bit microcontrollers and SoCs with more RAM and flash than small-scale systems. However, software complexity is orders of magnitude higher in this category with applications having tens of thousands to a million lines of code (LOC) or more.
Systems in this category are usually very complex with multiple features and capabilities. They often operate on server-like hardware that has multiprocessors. Applications often require real-time processing and may still use high-end RTOS or Linux. Examples of this include enterprise network switches and routers and telecommunication network backbone systems, stock exchange processing, and air traffic control. These systems are highly complex, interconnected with code bases of multiple millions of lines of code.
Despite the variety of applications there are some common characteristics such as the dedicated nature of the applications. Embedded systems often run all year round, 24 hours a day. They also share the need to be reliable, safe, power-efficient, and cost-effective to manufacture. More than ever is the need for them to be secure, which we’ll talk about later.
The applications of embedded systems are too numerous to list but the obvious high-profile examples include:
Our smartphones, tablets, smartwatches, and smart TVs are all embedded systems! Here are more applications that run on embedded systems:
In fact, 98% of microprocessors produced in the world are used in embedded systems.
As ubiquitous as embedded systems are there are still a lot of systems and software that aren’t. All desktop software such as productivity, web browsers, and video games aren’t considered embedded. Enterprise software, cloud infrastructure, and backend systems aren’t embedded either.
Usually, if it runs on generic hardware such as a typical PC or server, it’s not considered embedded. Physically, the applications aren’t bundled with hardware as one and inseparable. For example, PCs might ship with the Microsoft Windows operating system, but that operating system can be replaced and removed without altering the main function of the PC. Non-embedded software is usually application software that can run on a variety of hardware, remotely or locally.
Embedded systems play an important role in safety- and security-critical devices. Products like pacemakers and ABS brake controllers can’t fail. Lives depend on these devices working properly, all of the time. High-profile failures such as the Therac 25 incident where patients massively overdosed with radiation or the Ariane 5 rocket disaster caused by an integer overflow error.
Security is now a major concern as more embedded systems come online, connected through the internet (the Internet of things.) This interconnection creates new features and opportunities and opens the door to attacks. A litany of security problems in IoT devices is documented by our very own Code Curmudgeon in his IoT Hall of Shame. Insecure devices are unsafe so security and safety must be considered equally in these critical devices.
The only way to make sure embedded systems are safe and secure is through testing. More precisely, through rigorous verification and validation throughout the entire development life cycle. That includes before software development, in early requirements analysis, and all the way until end of life.
There are specific standards that must be followed by industries where safety is a major concern, including the following:
Manufacturers of these devices must follow the standards and prove via audits that they perform their due diligence and have addressed all concerns for security and safety. This type of hardware and software development is time-consuming and expensive to build and test, but essential to ensure correct behavior when deployed.
Embedded systems, particularly safety- and security-critical embedded systems, can’t fail. If they do, the consequences are dire. Lives will be lost or persons will sustain serious injury. There’s also the possibility of damage to property. Therefore, software testing is critical.
Software testing ensures that the embedded system is safe, secure, and reliable. Testing also helps in the certification of these facts. The functional safety standards mentioned in the previous section provide guidance and recommend testing methods like static code analysis, unit testing, integration testing, system testing, regression testing, structural code coverage, and many other types of hazard analysis, threat analysis, and risk assessment activities to ensure the safest and most secure embedded system possible.
Many embedded systems also have certification requirements imposed by federal regulatory agencies. The U.S. has the FDA for medical devices, the FAA for avionics, the NHTSA for motor vehicles, the FRA for rail, and there are more. These agencies impose regulations that keep the public safe and secure. In addition, companies themselves strive for quality, because recalls, lawsuits, and lengthy litigations can destroy a company.
