nanopb/nanopb

Nanopb is a Protocol Buffers implementation in ANSI C designed for embedded systems and memory-constrained environments.

Protocol Buffers provide a method for serializing structured data, but the standard implementation carries significant overhead unsuitable for microcontrollers. Nanopb solves this by offering a minimal code-size implementation that generates C code from .proto files. The approach uses a code generator that produces .pb.c and .pb.h files from standard Protocol Buffer definitions, which are then compiled alongside three core library files: pb_encode.c, pb_decode.c, and pb_common.c. This allows developers to use the Protocol Buffers format while keeping the footprint small enough for resource-constrained systems.

Nanopb suits projects targeting microcontrollers or any system with strict memory limitations where standard Protocol Buffers would be impractical. It maintains compatibility with the standard .proto file format, so message definitions work across different Protocol Buffers implementations. The tool includes an options file mechanism for customizing code generation behavior. Developers should expect to use the Python-based generator to compile their protocol definitions and then integrate the resulting C code into their build system. The project provides a simple example in examples/simple to demonstrate the workflow.

The project maintains automated testing across multiple platforms, including embedded targets such as STM32 discovery boards and AVR simulators via Scons-based test infrastructure. Development activity includes both scheduled weekly builds and builds triggered by code changes, indicating ongoing maintenance and verification of functionality across different compiler and platform combinations.