Embedded Software

Embedded software applications are specialized programming within non-PC devices – either as part of a microchip or as part of another application that sits on top of the chip – to control specific functions of the device. Unlike PC applications, which can be installed on a variety of computer systems and modified to provide different levels of functionality, embedded software has fixed hardware requirements and capabilities. It is created exclusively for the particular device that it runs on, with processing and memory restrictions tied directly to that device’s specifications. In the context of this discussion, embedded software includes applications, firmware, middleware, and operating systems that execute on a single microprocessor or cluster of microprocessors “embedded” within additional logic.

Example of embedded system architecture

Embedded software is used for a specific functionality that contributes to the overall operation of the device

What are the different types of embedded software and their purposes?

  • Operating System – An operating system (OS), in its most general sense, is software that allows a user to run other applications on a computing device. The operating system manages a processor’s hardware resources including input devices such as a keyboard and mouse, output devices such as displays or printers, network connections, and storage devices such as hard drives and memory. The OS also provides services to facilitate the efficient execution and management of, and memory allocations for software application programs.
  • Firmware – Firmware is a type of software that is written directly for a piece of hardware. It operates without going through APIs, the operating system, or device drivers—providing the needed instructions and guidance for the device to communicate with other devices or perform a set of basic tasks and functions as intended.
  • Middleware – Middleware is a software layer situated between applications and operating systems. Middleware is often used in distributed systems where it simplifies software development by providing the following:
    • Hiding the intricacies of distributed applications
    • Masking the heterogeneity of hardware, operating systems and protocols
    • Providing uniform and high-level interfaces used to make interoperable, reusable and portable applications.
    • Delivering a set of common services that minimizes duplication of efforts and enhances collaboration between applications
  • Application – The end-user develops the final software application that runs on the operating system, uses or interacts with the middleware and firmware, and is the primary focus of the embedded systems’ target function. Each end application is unique while operating systems and firmware can be identical from device to device.

Embedded Software vs Embedded Systems

The hardware components within a device that are running embedded software are referred to as an "embedded system." Some examples of hardware components used in embedded systems are power supply circuits, central processing units, flash memory devices, timers, and serial communication ports. During a device's early design phases, the hardware that will make up the embedded system – and its configuration within the device – is decided. Then, embedded software is developed from scratch to run exclusively on that hardware in that precise configuration. This makes embedded software design a very specialized field that requires deep knowledge of hardware capabilities and computer programming.

Examples of embedded software-based functions

Almost every device made with circuit boards and computer chips has these components arranged into a system that runs embedded software. As a result, embedded software systems are ubiquitous in everyday life and are found throughout consumer, industrial, automotive, aerospace, medical, commercial, telecom, and military technology.

Common examples of embedded software-based features include:

  • Image processing systems found in medical imaging equipment
  • Fly-by-wire control systems found in aircraft
  • Motion detection systems in security cameras
  • Traffic control systems found in traffic lights
  • Timing and automation systems found in smart home devices

What are the different types of embedded systems?

When based on performance and functional requirements, there are five main classes of embedded systems:

  • Real-time embedded systems complete tasks in a deterministic and repeatable manner, this is affected by the operating systems underlying architecture and scheduling, as well as the performance of threads, branching, and interrupt latency. General-purpose embedded systems are those that do not contain a real-time requirement and can manage interrupts or branching without a dependency upon a completion time. Graphics displays and keyboard and mouse management are good examples of general systems.
  • Stand-alone embedded systems can complete their task without a host system or external processing resources. They can output or receive data from connected devices but are not reliant on them to complete their task.
  • Stand-alone embedded systems can complete their task without a host system or external processing resources. They can output or receive data from connected devices but are not reliant on them to complete their task.
  • Networked embedded systems depend on a connected network to perform assigned tasks.
  • When based on the complexity of the system's hardware architecture, there are three main types of embedded systems: Networked embedded systems depend on a connected network to perform assigned tasks.

How end-markets affect embedded systems

Embedded system requirements and components will differ according to the demands of the target market. Some examples include:

  • Consumer – In applications like consumer goods such as washers, wearable devices, and mobile phones embedded systems emphasize the reduced size of the
  • System-on-chip, low-power consumption or battery operation, and graphics interfaces. In these applications, configurable operating systems, and the ability to shut off non-operating “domains” of the design are valued.
  • Networking – Applications that enable connectivity, communication, operations, and management of an enterprise network. It provides the communication path and services between users, processes, applications, services, and external networks/the internet. Embedded network applications focus on speed of response, packet processing, and peripheral hardware paths.
  • Industrial – For applications such as factory floor management, motors, and windmills the emphasis tends more towards secure cloud connectivity, and deterministic “real-time” operation and can focus heavily on middleware.
  • Medical, Automotive, and Aerospace – These industries have the need for mixed-safety critical systems, where portions of the design are isolated from each other to ensure only necessary data enters or leaves the system (security); while guaranteeing no harm comes to the end-user (safety). Examples are autonomous driving systems in automobiles and medical devices. These embedded systems can feature a mix of open source (Linux) and deterministic real-time operating systems (RTOS), and heavily utilize proven middleware.

Characteristics and features of embedded systems

Even though there are many types of embedded systems, they all share the same beneficial features and design characteristics.

  • All embedded systems are task specific. They execute the same pre-programmed function throughout their usable life and cannot be altered.
  • All embedded systems are high-efficiency. The resource requirements of embedded software should never exceed the capacity of the hardware it is installed on, and the hardware's specifications should never exceed the bare minimum requirements of the embedded software.
  • All embedded systems are designed to be highly reliable and stable. They are required to perform their task with consistent response times and function throughout the lifetime of the device that houses them.

Why is automotive embedded software different?

In automotive electronics, complex real-time interactions occur across multiple embedded systems that each control functions such as braking, steering, suspension, powertrain, etc. The physical housing that contains each embedded system is referred to as an electronic control unit (ECU). Each ECU and its embedded software is part of a complex electrical architecture known as a distributed system.

By communicating with each other, the ECUs that make up a vehicle’s distributed system can execute a variety of functions like automatic emergency braking, adaptive cruise control, stability control, adaptive headlights, and much more. A single function might need interactions across 20 or more embedded software applications spread across numerous ECUs connected by multiple networking protocols. Complex control algorithms deployed with the embedded software ensure the proper timing of functions, needed inputs and outputs, and data security.

Common examples of automotive software application-based features include:

  • ADAS (Advanced Driver Assist Systems) features like adaptive cruise control, automatic emergency braking, lane-keep assist, traffic-assist, lane-departure warnings
  • Battery management
  • Torque compensation
  • Fuel injection rate control

ECU software stack

The Electronic Control Unit or ECU is comprised of a main computing unit with chip-level hardware and a stack of embedded software. However, there is an increasing trend among automotive manufacturers of designing ECUs with complex integrated circuits that contain multiple computing cores on a single chip – what is referred to as a System on a Chip (SoC). These SoC can host a multitude of ECU abstractions in order to consolidate hardware. The software stack for an ECU typically includes a range of solutions, from low-level firmware to high-level embedded software applications.

ECU Stack  Description
Embedded software application Control algorithms, processing, services
Application framework Security & safety frameworks
Operating environment AUTOSAR classic, AUTOSAR Adaptive, Inputs/Output channels
Embedded virtualizations Real-time OS, ECU abstractions
Firmware Boot-loaders, secure-storage, secure-threading
Hardware Silicon based devices, micro-controllers, single or multiple layered boards

About Siemens Embedded Software

In 2017, Siemens acquired the Mentor Graphics company and the full portfolio of embedded software, which includes:

  • Sokol™ Flex OS and Sokol™ Omni OS – Previously known as the Mentor Embedded Linux products – Sokol Flex OS is a Linux- platform based on the Yocto Project, and Sokol Omni OS is a Linux platform based on Debian. with support for rich graphics, secure IoT and cloud enablement, and comprehensive development tools.
  • Nucleus™ RTOS – a unique royalty-free real-time operating system (RTOS) with advanced capabilities like process modeling, SMP, power management, graphics, and safety certification.
  • Sokol™ Embedded IoT Framework Add-on and Nucleus™ Embedded IoT Framework Add-on – a multi-cloud solution that enables secure IoT architectures while reducing complexity and costs associated with device porting, scaling, and backend integration.
  • Nucleus™ Multicore Framework – Allows developers to configure and deploy multiple operating systems and applications across homogeneous or heterogeneous processing cores by providing lifecycle management, boot order control, and inter-core communications to one another.
  • Nucleus™ Embedded Hypervisor – a small footprint type-1 hypervisor designed and built specifically for embedded applications. The high-performance capability of Hypervisor enables systems to boot quickly while minimizing the impact on guest operating system execution.
  • Sourcery™ CodeBench - Sourcery CodeBench delivers a powerful toolset that helps embedded software engineers efficiently develop and optimize software for a variety of targets and various domains including Automotive, Connectivity, Graphics, and Video applications.
  • Sourcery Toolchain Services – toolchain commercialization, customization, and support services that enable a wide variety of processor architectures
  • Runtime Services – professional assistance for customizing and developing Siemens Embedded products for a particular customer’s embedded system, such as customizing boot flow, IoT and Cloud services, Machine Learning flows, multicore processor enablement
  • and more...

In 2021, the Mentor brand name was discontinued. However, all of the tools are still offered and supported by Siemens with all of the same functionality that enables developers to create robust and feature-rich embedded systems.


Embedded Products

Man at keyboard using three screens to work

Siemens delivers embedded software solutions that enable device manufacturers to quickly design and build high-quality connected devices, including those with rich user interfaces, cloud-based remote management, or requiring safety certification. Base technologies include Linux, the Nucleus real-time operating system, advanced multicore runtime, and IoT enablement and development tools.