Testing Embedded Software: Ensuring Quality and Reliability

Embedded systems are everywhere – from automobiles and aeroplanes to medical devices and consumer electronics. These systems rely on software to function, and the quality and reliability of this software are critical. Testing embedded software is essential to ensure that these systems operate as intended and meet the necessary safety and performance standards.

Global embedded computing market growth chart showing projected increase to $65 billion by 2027 with upward trend arrow.

What is Embedded Testing?

Embedded testing is the process of verifying and validating embedded software and hardware to ensure that they meet the requirements and specifications, and there are proven ways to optimise your embedded software testing process once that baseline works. Embedded testing typically involves testing both the software and the hardware to ensure that they work together as intended. This type of testing is critical for embedded systems, as it is essential to ensure that the system operates reliably and safely.

How Many Embedded Test are There?

Several types of tests can be performed on embedded software, and the number of tests can vary depending on the complexity and size of the software. Here are some of the most common types of tests:

Unit Testing: This type of testing involves testing individual functions or modules of the software to ensure that they are working as expected. Unit tests are usually automated and can be run frequently during development processes.
Integration Testing: This type of testing involves testing how different modules or components of the software interact with each other. Integration tests are important to identify and resolve issues that arise from the interaction between different parts of the software.
System Testing: This type of testing involves testing the software as a whole to ensure that it meets the required specifications and performs as expected. System testing can include functional testing, performance testing, security testing, and other types of testing.
Acceptance Testing: This type of testing is performed to ensure that the software meets the requirements of the stakeholders. Acceptance testing can be done by the customer or a representative from the customer’s organization.
Regression Testing: This type of testing is performed after changes are made to the software to ensure that the changes did not introduce any new issues or regressions. Regression testing can be automated to save time and effort.
Load Testing: This type of testing involves testing the software under heavy loads to ensure that it can handle the expected amount of traffic or usage. Load testing can help identify performance issues and bottlenecks.
Stress Testing: This type of testing involves testing the software under extreme conditions, such as high temperatures or low memory, to ensure that it can handle unexpected situations.
Usability Testing: This type of testing involves testing the software to ensure that it is easy to use and understand for the end-users.

8 popular embedded software test types listed: unit testing, load testing, integration testing, usability testing,…

Overall, the number and types of tests required for embedded software can vary depending on the complexity of the software, the requirements, and the environment in which it will be used. It is important to consider all possible scenarios and use cases when testing embedded software to ensure that it is reliable, robust, and performs as expected.

Unit tests that never touch real hardware hide the failures that matter: timing, memory and peripheral behaviour under load. We build test strategies that run on target, not only on a host.

Catch embedded defects before the field does

Software Testing Challenges

Several software testing challenges can affect the quality of software and pose significant risks to software projects. Here are some of the most crucial software testing challenges, each of them examined in our guide to common challenges in embedded software testing:

Line graph showing six challenging software testing situations: bad testing environment, time constraints, lack of…

Time Constraints: One of the biggest challenges in software testing is time constraints. Software development projects are often under tight schedules, and testing is often the first area to be cut or reduced in scope to meet deadlines. This can lead to incomplete testing and the release of the software with defects.
Bad Testing Environment: Testing software requires an environment that closely mimics the production environment. However, it can be challenging to create such an environment due to the complexity of software systems, the difficulty of simulating real-world scenarios, and the cost of hardware and software resources required to set up the environment.
Lack of Test Coverage: Test coverage refers to the percentage of the software that is tested. It is essential to achieve high test coverage to ensure that all possible scenarios are covered. However, it can be challenging to achieve high test coverage, especially in complex systems, due to the number of test cases required.
Changing Requirements: Requirements for software projects can change frequently, leading to a mismatch between the software design and the actual requirements. This can cause issues with testing, as testers may not have access to the latest requirements or may be testing against outdated requirements.
Test Data Management: Test data is critical to software testing, and managing test data can be challenging, especially in large software systems. Test data needs to be created, maintained, and managed properly to ensure that tests are accurate and repeatable.
Test Automation: Test automation can be challenging, especially in complex software systems. Automation requires a significant investment in tools, infrastructure, and resources, and it can be difficult to automate tests for all scenarios, especially those that require manual intervention or human judgment.
Communication and Collaboration: Communication and collaboration between different teams and stakeholders are essential for successful software testing. However, it can be challenging to maintain effective communication and collaboration, especially in distributed teams or when dealing with stakeholders with different backgrounds and expectations.

24% statistic with bar chart showing companies experiencing immediate ROI on automated testing investments

These challenges can significantly impact the quality of software and the success of software projects. Addressing these challenges requires careful planning, resources, and expertise in software testing.

Embedded Hardware Testing Tools

There are multiple embedded hardware testing tools:

Oscilloscopes: Used to analyze and measure electronic signals in hardware designs.
Logic Analyzers: Used to capture and display digital signals in hardware designs.
JTAG Debuggers: these testing solutions provide access to the JTAG (Joint Test Action Group) interface on devices.
Boundary Scan Testers: A hardware testing tool that provides non-intrusive testing of digital signals in hardware designs.
Protocol Analyzers: Used to analyze and decode communication protocols in target hardware designs.

InTechHouse knows how essential is to choose the right testing tools to ensure that embedded systems meet their performance, reliability, and safety requirements.

Embedded Software Testing Tools

Here are some popular tools for embedded software testing checks:

Ceedling: An open-source software testing framework that provides automated testing of embedded C applications.
Unity: A lightweight unit testing framework for C and C++ embedded systems.
LDRA: A testing tool that provides automated software verification and validation for embedded systems.
Parasoft: A software testing tool that provides automated software testing and verification for embedded systems.

Why Embedded Software Quality is Important

The quality and reliability of embedded software are critical, as embedded systems are often used in safety-critical applications, so the quality attributes in embedded systems have to be defined before the first test case. A failure in an embedded system can have severe consequences, such as loss of life or property damage. Testing embedded software is essential to ensure that the system operates reliably and safely and meets the necessary safety and performance standards.

Also, it’s necessary to provide embedded security testing. We can describe it as a process of evaluating the security of an embedded system. It involves identifying vulnerabilities and threats to the system and verifying that the security controls in place are effective in protecting the system from attacks. Here is a common software testing technique for embedded security testing:

Penetration software testing involves a simulation of an attacker’s attempts to exploit vulnerabilities in the system. Penetration testing involves testing for vulnerabilities in the system and exploiting them to determine their impact on the system’s security.
Fuzz software testing involves sending random input to the system to identify any unexpected behaviour. Fuzz testing can uncover buffer overflows, code injection, and other vulnerabilities.
Code coverage analysis software testing involves analyzing the source code to identify any security vulnerabilities. Code analysis tools can scan the source code for known vulnerabilities, such as buffer overflows and code injection.
Protocol analysis: This testing process includes analyzing the communication protocols used by the system to identify any security weaknesses in complete software code. Protocol analysis tools can help identify potential security issues, such as message tampering or unauthorized access.
Risk analysis is some kind of traditional software testing when identifying and evaluating the risks to the system. It involves identifying the assets that need protection, the potential threats, and the vulnerabilities in the system. Based on this analysis, security controls can be implemented to mitigate the risks.

Infographic stating cybersecurity spending expected to reach $133.7 billion in 2022, presented by IN Tech House.

Source: Truelist

‍In summary, embedded security testing involves using a combination of techniques, such as penetration testing, fuzz testing, code analysis, protocol analysis, and risk analysis, to identify and mitigate security vulnerabilities in embedded systems. By conducting thorough security testing, embedded systems can be designed to be more secure and better protected against potential security threats.

How to Test Embedded Software and Who Should Do it

To test embedded software effectively, it is essential to develop a comprehensive testing strategy that includes functional testing, integration testing, performance testing, and system testing. It is also crucial to test the software in real-world environments to ensure that it works as intended under various conditions. Testing should also be automated wherever possible to reduce the time and effort required for testing.

Embedded system testing is a specialized field that requires expertise in both software and hardware testing. Here are some entities that can provide embedded system testing:

In-house Testing Teams: Many companies have their in-house testing teams that specialize in embedded system testing. These teams are familiar with the company’s products and processes and can perform comprehensive testing to ensure that the embedded systems meet their performance, reliability, and safety requirements.
Testing Service Providers: Many third-party testing service providers specialize in embedded system testing. These providers have expertise in both software and hardware testing and can perform comprehensive testing of embedded systems. They often have a wide range of embedded testing tools and techniques for creating a better embedded testing process
Independent Testing Consultants: Independent testing consultants can provide expert advice and guidance on embedded system testing. They can work with companies to develop testing strategies, identify potential risks and issues, and help improve the overall quality of embedded systems
Original Equipment Manufacturers (OEMs): OEMs can also provide embedded system testing services. They are familiar with the products they manufacture and can perform comprehensive testing to ensure that their products meet their performance, reliability, and safety requirements.INTechHouse has huge expertise in embedded system testing performed by our in-house testing teams. We have has experience in both software and hardware testing and can perform comprehensive testing to ensure that their embedded systems meet the client’s requirements

Challenges in Embedded System Design

Designing embedded systems presents several challenges, including selecting the right hardware and software components, managing limited resources, and ensuring the system’s reliability and safety. It is essential to consider these factors carefully during the design phase to ensure that the system meets the requirements and specifications.

The software testing process is critical to ensure that embedded software development works reliably, which is why testing is built into our embedded firmware and software development services. This type of testing presents several challenges, but with the right testing tools and strategies, it is possible to develop high-quality, reliable embedded systems. Quality and reliability are essential in embedded systems, as failures can have severe consequences, making testing an essential aspect of embedded system design and development.

Our engineers build regression suites, hardware in the loop rigs and CI pipelines for devices that have to stay reliable for years. Ask us to review your current test coverage and where it leaks.

See how we set up embedded test automation for your product

Conclusion

Testing embedded software is a crucial process that ensures the reliability, safety, and performance of the software. Effective testing can help identify and fix bugs, optimize performance, and enhance the overall user experience. With the growing demand for embedded software in various industries, it’s important to prioritize thorough testing to ensure that products meet the highest standards of quality and safety.

To improve the testing process for embedded software, companies can consider implementing automated testing tools, leveraging agile methodologies, and investing in employee training and development. By taking these steps, companies can ensure that their embedded software meets the highest standards of quality, while also reducing costs and improving time-to-market.

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FAQ

What is embedded software testing and how is it different from regular software testing?

Embedded software testing verifies that firmware behaves correctly on its target hardware, including timing, memory use, peripheral behavior and response to real electrical signals. Regular software testing can usually run everything on a developer machine or in the cloud. Embedded testing must also cover interrupts, power loss, sensor noise and hardware variants, so it combines host-based unit tests with on-target tests, instrument measurements and system tests on real or simulated hardware.

What is the difference between host-based unit testing and on-target testing?

Host-based unit testing compiles embedded C modules for a PC and runs them with frameworks such as Unity or Ceedling, using mocks in place of hardware registers. It is fast and fits into CI, so it catches logic errors early. On-target testing runs the code on the real microcontroller, where compiler differences, stack limits, interrupt timing and peripheral quirks appear. A sound strategy uses both: host tests for logic, target tests for anything that depends on the hardware.

What is hardware-in-the-loop testing and when is it needed?

Hardware-in-the-loop (HIL) testing runs the real controller hardware and firmware against a simulated environment that generates sensor signals and reacts to actuator outputs in real time. It is needed when the real system is expensive, dangerous or slow to test, such as a vehicle, a power converter or a medical device. HIL makes fault scenarios repeatable, for example a sensor failure at full load, and allows those scenarios to run automatically on every firmware release.

How much code coverage is enough for embedded software?

Enough code coverage for embedded software depends on the risk of failure and the applicable standard. For general products, high statement and branch coverage from unit tests is a reasonable target. Safety standards go further: DO-178C requires modified condition/decision coverage (MC/DC) for Level A airborne software, and ISO 26262 highly recommends MC/DC at ASIL D. Coverage alone proves only that code ran, not that it was checked, so assertions and requirement traceability matter as much.

Which tools are used to test embedded software and hardware?

Embedded testing uses a mix of software frameworks and bench instruments. On the software side, Unity and Ceedling handle unit tests in C, while LDRA and Parasoft add static analysis, coverage measurement and compliance reporting for standards such as MISRA C. On the hardware side, JTAG or SWD debuggers, logic analyzers, oscilloscopes and protocol analyzers show what the code actually does to pins and buses. Boundary scan testers check board connectivity during production.

Should embedded software testing be done in-house or by an independent team?

Embedded software testing is best split: developers own unit and integration tests in-house, while an independent team or external test provider is useful for system, security or certification testing. Safety standards such as ISO 26262 and DO-178C expect a degree of independence in verification at higher risk levels. An external provider also makes sense when the team lacks HIL rigs, test automation experience or domain knowledge of the target standard, and when release schedules leave no time to build them.

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Krzysztof Niedźwiedź

Lead Embedded Systems & Hardware Engineer

Krzysztof Niedźwiedź is a Lead Embedded Systems and Hardware Engineer at InTechHouse with over 11 years of experience developing complex electronic and embedded products from system architecture through production.

He specializes in embedded software development, electronic system architecture, multilayer PCB design, hardware-software integration, system testing, and technical ownership of high-reliability engineering projects. His work spans requirements analysis, architecture and component selection, schematic and PCB design, bare-metal and RTOS firmware development, prototyping, troubleshooting, production documentation, and cooperation with mechanical and high-level software teams.

Krzysztof's project experience includes FPGA and SoC-based onboard computers for the space industry, embedded electronics for advanced optical equipment, low-power environmental-monitoring devices, UAV payloads for real-time air-quality measurement and sample collection, and connected medical and training devices.

He works with C and C++, STM32, LPC and AVR microcontrollers, ARM-based platforms, RTOS, Embedded Linux, FPGA and SoC architectures, DDR3, HDI PCB technology, and industrial communication interfaces including Ethernet, CAN, RS-485, SPI, I2C, UART, USB, Modbus, and MQTT.

Krzysztof holds bachelor's and master's degrees in Electronics and Telecommunications. He is an IPC Certified Interconnect Designer and has completed specialist training in Embedded GNU/Linux kernel internals and device drivers. He writes about embedded system architecture, firmware development, PCB design, MCU and FPGA integration, RTOS, hardware security, low-power electronics, and dependable electronic products.

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