MISRA-C: What Is It and Why Do You Need It? What Would Life Be Without It?

At Genesys Electronics Design, we understand that embedded systems demand more than just functional code. They demand reliable, safe, and maintainable software that performs under pressure. That’s why, on nearly every project involving C code (which includes most of our firmware-based work), we apply MISRA-C, an industry-recognised set of coding guidelines designed for high-integrity systems.

Whether we’re working on medical devices, industrial monitoring systems, or energy-efficient embedded platforms, MISRA-C forms the backbone of our software development standards.

Why We Use MISRA-C on (Almost) Every Embedded Project

We’ve been using MISRA-C since our work on early projects like TruScreen over a decade ago. Today, all the libraries we develop and reuse across projects are MISRA-C compliant, ensuring that they’re trustworthy and production-ready, even for mission-critical systems.

While not every project involves C, for instance, some mobile or web applications use JavaScript or Python, MISRA-C is part of our process on nearly every project that includes a microcontroller, which is most of them.

“We develop all our reusable libraries under MISRA-C, making them dependable building blocks for safety- and security-critical applications.”

— George, CEO at Genesys Electronics Design

But what exactly is MISRA-C, why does it matter and what would life be like without it?

Table of Contents

• What is MISRA-C

• Why Do You Need MISRA-C?

• What would life be like without MISRA-C?

• Applying MISRA-C the right way

• The Genesys Approach

What is MISRA-C?

MISRA-C is a set of guidelines for writing safe, secure, and reliable C code, developed by the Motor Industry Software Reliability Association (MISRA). Originally created for the automotive industry, it has since become a widely adopted coding standard across many high-integrity industries like aerospace, medical devices, industrial controls, and more.

The C programming language is powerful, flexible, and ubiquitous in embedded systems, but it’s also notoriously prone to errors. Memory leaks, undefined behaviours, and subtle bugs can lurk in even the simplest codebases. MISRA-C addresses this by setting out a comprehensive list of rules and recommendations designed to avoid the risky parts of the C language.

Why Do You Need MISRA-C?

Implementing MISRA-C isn’t just about writing cleaner code, it’s about building trust in your software. In embedded systems, the cost of a software bug can be massive: from product recalls to safety hazards. MISRA-C helps reduce those risks by guiding developers away from ambiguous or error-prone coding practices.

But the benefits go beyond the code itself:

1. Enhancing Code Safety and Reliability

MISRA-C minimises risks associated with software bugs and undefined behaviours in C programming. By enforcing disciplined coding practices, it helps in reducing system failures that can lead to catastrophic consequences, especially in automotive, aerospace, and medical industries.

2. Reducing Development and Maintenance Costs

Detecting and fixing software bugs in later stages of development can be costly. MISRA-C helps prevent these issues early through static code analysis and runtime linters like PC-Lint, which catch violations before they lead to real-world problems. The result is a smoother, more predictable development process.

3. Regulatory Compliance

Industries like medical (IEC 62304), automotive (ISO 26262), and railway (EN 50128) require software to meet stringent safety standards. MISRA-C helps in achieving compliance with these regulatory frameworks, making it easier for companies to get their products certified.

4. Portability and Reusability

MISRA-C promotes writing clean and portable code, ensuring that software can be reused across different platforms without significant modifications. This reduces duplication of effort and speeds up development cycles.

5. Facilitating Team Collaboration

A well-defined coding standard ensures consistency across teams, making it easier for developers to understand each other’s code. This improves code reviews, debugging, and overall collaboration in large-scale projects.

What Would Life Be Like Without MISRA-C?

Imagine a world where developers write C code without any structured guidelines like MISRA-C. Imagine developing safety-critical systems with no guardrails, where hidden coding errors could lurk undetected until they cause catastrophic failures. Without MISRA-C, embedded software would be far more vulnerable to unpredictable crashes, security breaches, and costly recalls.

What could possibly go wrong? 

• Subtle bugs go unnoticed until something breaks in the field.

• Debugging time increases, and confidence in the system drops.

• Certification becomes a headache, or worse, impossible.

• Maintenance becomes a risky game of guesswork.

The result? Increased development costs, delayed launches, reputational damage, and real-world safety risks.

Applying MISRA-C the Right Way

Building upon our earlier discussion on MISRA-C, it's important to recognise that while MISRA-C provides a robust framework for writing safer and more reliable C code, it is not a panacea. As highlighted by Chris Hills, CTO of Phaedrus Systems, in his article "MISRA C Is Useful – But It Is Not A Lifebelt," the guidelines serve as building blocks to create a coding standard tailored to specific project needs. 

MISRA-C should be integrated into a disciplined and structured development process. Simply aiming for 100% MISRA C compliance without understanding the rationale behind each guideline can be counterproductive. The guidelines are designed to be adapted, with the option to deviate from certain rules when justified and properly documented. This flexibility allows teams to address the unique challenges of their projects while maintaining code quality and safety.​ Moreover, MISRA-C compliance should be complemented with other best practices, such as thorough requirements specification, static and dynamic code analysis, and rigorous testing. These practices ensure that the code not only adheres to standards but also fulfills its intended functionality and performance criteria.​  

Applying MISRA-C the Right Way

The Genesys Approach

At Genesys, we don’t just adopt MISRA-C because it’s a standard, we integrate it as part of our broader commitment to quality and reliability on every project. We understand that while MISRA-C sets the foundation for safer, more reliable code, it’s only effective when combined with strong engineering practices, thorough testing, and a culture of continuous improvement.

Our approach goes beyond compliance. We tailor the guidelines to fit each project's unique needs, ensuring that every line of code serves a purpose and contributes to the overall integrity of the system. By embracing MISRA-C, we provide our clients with the confidence that their embedded systems are not only compliant but also robust, secure, and built to stand the test of time.

We use MISRA-C on every project that involves C, which includes nearly every project we work on involving a microcontroller. For higher-level application layers where C isn't used (e.g. mobile or web apps), we apply similar principles using linting tools in Python, JavaScript, or other appropriate technologies.

A big factor is that we develop all our reusable libraries under MISRA-C. These are used across projects, making them inherently trustworthy and ready for mission-critical use.

One recent example is our work with Electrogenics, where MISRA-C was instrumental in delivering reliable embedded firmware for radiation dosimetry systems.

While we first began applying MISRA-C during early projects like TruScreen, we're now seeing even chip manufacturers like ST modifying their codebases to become MISRA-compliant. It's a validation of the path we’ve followed for over a decade.

Need help building MISRA-compliant embedded systems?

Get in touch with the team at Genesys Electronics Design, we’re here to help turn your vision into reality, safely and reliably.