The most appropriate group to review this topic would be Embedded Systems Engineers and Firmware Architects specializing in the Zephyr RTOS ecosystem.

Expert Persona: Senior Firmware Architect

Abstract:

This technical session outlines the implementation of Protocol Buffers (Protobuf) within the Zephyr RTOS environment, specifically utilizing the Nanopb module. The presenter details the integration process for the nRF9160 Feather, emphasizing the use of Zephyr’s native CMake functions to automate the compilation of .proto definition files into C source and header files.

Key technical requirements include the installation of the protoc compiler, the inclusion of the Nanopb module within the west.yml manifest, and the activation of CONFIG_NANOPB in the project configuration. The session demonstrates the lifecycle of a Protobuf message—covering static memory allocation, stream-based encoding, and decoding—while highlighting the advantages of Proto2 syntax for resource-constrained embedded applications. The workflow ensures that generated assets remain within the build directory to maintain a clean source tree.

Implementing Nanopb in Zephyr RTOS: Build Automation and Message Lifecycle

• 0:00:18 Protocol Buffers in Zephyr: Overview of using Protobuf as a structured data exchange format within the Zephyr RTOS framework.
• 0:02:11 Reference Implementation: Utilization of built-in Zephyr samples modified for the nRF9160 Feather hardware, requiring specific bootloader and partition manager configurations.
• 0:02:52 CMake Integration: Use of the nanopb_generate_cpp (or C equivalent) CMake function to automatically compile .proto files into usable C code during the west build process.
• 0:03:12 Tooling Prerequisites: Requirement for the protoc (Protocol Buffer Compiler) to be installed on the host system and correctly linked in the system path.
• 0:04:12 West Manifest Configuration: Necessity of adding the nanopb module to the west.yml manifest to ensure the source is pulled into the Zephyr workspace.
• 0:05:07 Kconfig Requirements: Enabling the module via CONFIG_NANOPB=y to expose the necessary public functions and headers for the application.
• 0:07:32 Build Artifact Location: Generated .pb.c and .pb.h files are stored in the project's build directory (build/zephyr/src/), which is automatically added to the compiler's include path.
• 0:08:19 Static Memory Management: Protobuf allows for static calculation of maximum buffer sizes at compile time, providing a deterministic alternative to formats like CBOR for memory-constrained devices.
• 0:09:30 Encode/Decode Lifecycle: Implementation details involving the creation of pb_ostream_t and pb_istream_t streams for serializing and de-serializing messages.
• 0:12:57 Proto2 vs. Proto3: A preference for Proto2 syntax in embedded C projects is noted, as it facilitates simpler static struct allocation without the pointer complexities often found in Proto3.
• 0:14:12 Zephyr Developer Summit: Announcement of the upcoming summit (June 8-9) in Mountain View, CA, featuring deep-dives into Zephyr subsystem developments.