EmbeddedProto

Copyrichts 2020 Embedded AMS B.V. Amsterdam, www.EmbeddedAMS.nl, info@EmbeddedAMS.nl

Introduction

EmbeddedProto is a C++ implementation of Google Protocol Buffers dedicated for micro controllers. This means the implementation focuses on a small footprint and low memory usage. No dynamic memory allocation is used and the code is checked to be in line with the MISRA C++ guideline.

In this way EmbeddedProto provides an easy to use interface to exchange data between embedded devices and the out side world. Specifying the data format between your device and other devices, servers, apps or desktop applications in a standardized way.

This document details the following:

• Supported Features
• Installation
• Usage
• Development

Supported Features

All features mentioned below are proto3. At this moment proto2 is not supported. Taken from the Protobuf website:

Prefer proto3 While proto2 will continue to be supported, we encourage new codes to use proto3 instead, which is easier to use and supports more languages. For this reason it is unlikely we will support proto2 in the future.

Currently EmbeddedProto is work in progress. Below two tables are given indicating the level of support for various variable types and features.

Variable Type	Support
double	Full
float	Full
int32	Full
int64	Full
uint32	Full
uint64	Full
sint32	Full
sint64	Full
fixed32	Full
fixed64	Full
sfixed32	Full
sfixed64	Full
bool	Full
string	Under Development
bytes	Under Development

Feature	Support
Enum	Full
Other Messages	Full
oneof	Full
singular	No support
repeated	Full

Installation

What is required to be able to generate the source files:

1. Python 3.6
2. Pip
3. Protobuf 3.6.1
4. CMake 3.10.2 (required to build the PC unit tests)
5. Git if you do not have it already.

Install the required software and continue with checking out the repository. For PC unit testing gtest is used which is included as a submodule. If you intent to run the PC unit tests of EmbeddedProto it is suggested that you pull in the submodules as well.

Besides the list of tools above additional python packages are required. These are listed in the requirements.txt file in this repository. It is advised to install these required packages using pip in a python virtenv. You can however install the requirements globally. To install the packages run the command:

pip install -r requirements.txt

Usage

When working on your project you write your proto files. Next the would like to use them in your source code. This requires you to generate the code based upon the definitions you have written. This is done using our plugin for the protoc compiler protoc-gen-eams.py. To generate the code use the following command:

protoc --plugin=protoc-gen-eams -I./LOCATION/PROTO/FILES --eams_out=./build PROTO_MESSAGE_FILE.proto

What happens is that protoc is toled to use our plugin with the option --plugin. Next the the standard option -I includes a folder where your *.proto files are located. The option --eams_out specifies the location where to store the generated source code. Finally a specific protofile is set to parse.

As our plugin is a Python script and the protoc plugin should be an executable a small terminal script is included. This terminal

Development

PC Unit Tests

The unit tests for PC are mend to test the logic of EmbeddedProto. The test are build upon the GTest and GMock libraries which are include as a submodule in this repository.

The tests are build using a small script in the root folder of the project:

./build_test.sh

This will:

1. Generate message source files. The generated files are located in ./build/EAMS/.
2. Compile GTest and GMock into ./build/google/.
3. Build the unit tests into ./build/test.

To run the unit test execute:

./build/test/test_EmbeddedProto