Learn MISRA-C-AVIONICS with Real Code Examples

MISRA C defines a subset of C with mandatory, required, and advisory rules to avoid unsafe constructs.

It focuses on eliminating undefined, unspecified, and implementation-defined behaviors.

Widely adopted in aerospace, automotive, and defense systems for safety certification.

Supports static analysis and code review compliance processes.

Facilitates maintainable and portable code across compilers and platforms.

Restrictions on dynamic memory allocation

Prohibition of dangerous constructs (goto, setjmp, recursion in certain contexts)

Type safety and strict conversions

Structured control flow and function usage guidelines

Portability and predictability enforcement across compilers

Mandatory Rules - must be strictly enforced

Required Rules - should be enforced unless justified deviation exists

Advisory Rules - guidance for best practices

Undefined Behavior - code constructs that are unpredictable across compilers

Deviation - formal documentation when a rule is intentionally not followed

Source code files (.c/.h) conforming to MISRA C

Configuration files for compliance checker

Documentation for deviations and exceptions

Build scripts ensuring rule compliance before compilation

Test suites for functional and safety verification

Write C code following MISRA subset rules

Run static analysis to detect rule violations

Document justified deviations if any

Iterate and correct violations before integration

Review and verify compliance during code reviews

Beginner: simple embedded C modules with basic rule compliance

Intermediate: multi-module avionics subsystems with full compliance checks

Advanced: integrating MISRA compliance in complex RTOS or safety-critical systems

Expert: full DO-178C software lifecycle including verification and deviation management

Certifier: auditing software projects for MISRA C adherence and safety compliance

MISRA C vs Standard C: safer, restricted subset

MISRA C vs CERT C: avionics vs general embedded safety

MISRA C vs DO-178C guidelines: MISRA is code-level, DO-178C is lifecycle-level

MISRA C vs Coding without guidelines: predictable, verifiable, and certifiable

MISRA C vs AUTOSAR C: automotive vs avionics standards

1998 - MISRA C first edition for automotive

2004 - MISRA C:2004 introduced updates for embedded systems

2012 - MISRA C:2012 consolidated and enhanced rules

2016 - MISRA C:2012 Amendment 1, updated for wider safety-critical use

2020 - MISRA C:2020 revised for modern C and embedded applications

2023 - Latest updates focus on avionics-specific guidance and tool support

Undefined Behavior - operations with unpredictable outcome

Deviation - formally documented exception to a rule

Rule Classification - mandatory, required, advisory

Static Analysis - automated code inspection for compliance

Embedded System - dedicated hardware with software for a specific function