Point One FusionEngine Client

This library provides message definitions and support functionality for interacting with Point One FusionEngine in real time, as well as processing recorded output data. Both C++ and Python are supported.

Click here to download the latest FusionEngine protocol specification PDF: Point One FusionEngine Message Specification

See http://docs.pointonenav.com/fusion-engine/ for the latest C++ API documentation.

This library is released under the MIT license agreement. We welcome code and documentation contributions from users. See Contributing for instructions on how to report issues and develop, test, and submit code changes.

If you encounter an issue, please submit a ticket. If you need support with Point One FusionEngine or a Point One device (Atlas, Quectel LG69T, etc.), please contact [email protected].

Table Of Contents

• Requirements
• Directory Structure
  • Example Applications
• Installation
  • CMake
    • Including In Your CMake Project
    • Compiling From Source (Linux)
    • Compiling From Source (Windows)
    • Running Examples
  • Bazel
    • Including In Your Bazel Project
    • Compiling From Source
    • Running Examples
  • Python
  • Compiling Documentation
• Implementation Notes
  • Message Packing
  • Endianness
• Usage
  • Body Coordinate Frame Definition

Requirements

C++ Support

• C++11 or later
• CMake 3.x or Bazel 3.x
• GCC, Clang, or Microsoft Visual Studio

Python Support

• Python 3.8 or later

Documentation Build Support (Optional)

• Doxygen version 1.8.18
  • Versions 1.8.19 and 1.8.20 have a known issue with enum documentation and do not currently work

Directory Structure

• <root> - Top-level Bazel and CMake build files (C++)
  • examples/ - C++ example applications
  • python/ - Python source files
    • bin/ - Analysis and processing tools
    • examples/ - Python example applications
    • fusion_engine_client - Top Python package directory
      • messages - Python message definitions
      • parsers - Message encoding and decoding support
  • src/ - C++ source files
    • point_one/
      • fusion_engine/
        • messages/ - C++ message definitions

Example Applications

The examples/ directory contains example applications demonstrating how to use this library. They are:

• external_cmake_project - Download a copy of the FusionEngine Client library from the public repository and import it into a CMake project using FetchContent.
• generate_data - Generate a binary file containing a fixed set of messages.
• lband_decode - Example of decoding RTCM corrections from a recorded file containing LBandFrameMessage.
• message_decode - Parse and print the contents of messages contained in a binary file using the FusionEngineFramer class.
• raw_message_decode - Parse and print the contents of messages directly from a binary file without a helper class.
• request_version - Simulate sending a request for a version info message, and waiting for a response.
• tcp_client - Connect to a device over TCP and display the received FusionEngine messages.
• udp_client - Connect to a device over UDP and display the received FusionEngine messages.

Installation

CMake

Including In Your CMake Project

To include this library as part of your CMake project, we recommend using the CMake FetchContent feature as shown below, rather than compiling and installing the library manually as in the sections above:

# Download the specified version of the FusionEngine client library and make it
# available.
include(FetchContent)
FetchContent_Declare(
    fusion_engine_client
    # Recommended:
    URL https://github.com/PointOneNav/fusion-engine-client/archive/refs/tags/v1.22.3.zip
    URL_HASH MD5=cfe1de319725822a1b825cd3421fb6b1
    # Alternatively:
    # GIT_REPOSITORY https://github.com/PointOneNav/fusion-engine-client.git
    # GIT_TAG v1.22.3
)
set(P1_FE_BUILD_EXAMPLES OFF CACHE INTERNAL "")
FetchContent_MakeAvailable(fusion_engine_client)

# Define your application and add a dependency for the FusionEngine client
# library.
add_executable(example_app main.cc)
target_link_libraries(example_app PUBLIC fusion_engine_client)

Note that we strongly recommend using a specific version of the library in your code by specifying a release zip file or a git tag (e.g., GIT_TAG vA.B.C), and updating that as new versions are released. That way, you can be sure that your code is always built with a known version of fusion-engine-client. If you prefer, however, you can tell CMake to track the latest changes by using GIT_TAG master instead.

See examples/external_cmake_project/CMakeLists.txt for more details.

Compiling From Source (Linux)

Use the following steps to compile and install this library using CMake:

mkdir build
cd build
cmake ..
make
sudo make install

This will generate libfusion_engine_client.so, and install the library and header files on your system. By default, this will also build the example applications. You can disable the example applications by specifying cmake -DP1_FE_BUILD_EXAMPLES=OFF ...

Compiling From Source (Windows)

Use the following steps to compile and install this library using CMake and MSBuild:

mkdir output
cd output
cmake ..
MSBuild p1_fusion_engine_client.sln

Note: For Windows, we name the build directory output. Windows is not case-sensitive, and build conflicts with the Bazel BUILD file.

Running Examples

By default, the compiled example applications will be located in build/examples/ and can be run from there:

./build/examples/message_decode/message_decode

Bazel

Including In Your Bazel Project

To use this library in an existing Bazel project, add the following to your project's WORKSPACE file:

git_repository(
    name = "fusion_engine_client",
    remote = "[email protected]:PointOneNav/fusion_engine_client.git",
    tag = "v1.22.3",
)

Note that we strongly recommend using a specific version of the library in your code by specifying a git tag (e.g., tag = "v1.22.3"), and updating that as new versions are released. That way, you can be sure that your code is always built with a known version of fusion-engine-client. If you prefer, however, you can tell Bazel to track the latest changes by using branch = "master" instead.

After declaring the repository in your WORKSPACE file, you can add the following dependency to any cc_library() or cc_binary() definitions in your project's BAZEL files:

cc_library(
    name = "my_library",
    deps = [
        "@fusion_engine_client",
    ],
)

If desired, you can add a dependency for only part of the library. For example, to depend on only the core message definitions and support code, set your deps entry to @fusion_engine_client//:core.

Compiling From Source

In general, it is strongly recommended that you let Bazel import and compile the library using git_repository() as shown above. If you would like to compile the library manually, however, you can run the following command:

bazel build -c opt //:libfusion_engine_client.so

The generated file will be located at bazel-bin/libfusion_engine_client.so.

Running Examples

Note: The /examples directory has been structured like a stand-alone Bazel project to illustrate how to integrate this library into your own project. The bazel-bin/ directory below refers to <root>/examples/bazel-bin/.

To build all example applications, navigate to the examples/ directory and run the following:

bazel build -c opt //:*

Alternatively, you can build individual applications as follows:

bazel build -c opt //message_decode

The generated applications will be located in bazel-bin/. For example:

bazel-bin/message_decode/message_decode message_decode/example_data.p1log

You can also use the bazel run command to build and run an application in one step:

bazel run -c opt //message_decode -- message_decode/example_data.p1log

Python

See Point One FusionEngine Python Client for complete details and usage examples.

Install From PyPI

1. Install Python 3.8 (or later) and pip.
2. Install the fusione-engine-client module, including all analysis and data processing tools:

   python3 -m pip install fusion-engine-client[all]

   • Note: If you wish to only install data parsing support, and do not want to install plotting and other requirements used by the analysis tools in bin/, you may omit [all] and run python3 -m pip install fusion-engine-client
3. Run any of the applications in bin/. For example, to plot results from a *.p1log file from a Point One device:

   p1_display /path/to/log/file_or_directory

Install From Source (Development)

1. Install Python 3.8 (or later) and pip.
2. Clone a copy of this repository:

   git clone https://github.com/PointOneNav/fusion-engine-client.git

3. Install the Python requirements:

   python3 -m pip install -r requirements.txt

4. Run any of the applications in bin/ or the example code in examples/. For example, to plot results from a *.p1log file from a Point One device:

   python3 bin/p1_display /path/to/log/file_or_directory

Compiling Documentation

The documentation for the latest release is generated automatically and hosted at http://docs.pointonenav.com/fusion-engine/. If you would like to build documentation locally, simply run doxygen from the repository root directory. The generated output will be located in docs/html/. To view it, open docs/html/index.html in a web browser.

Implementation Notes

Message Packing

The canonical definitions for the FusionEngine messages are their C++ struct definitions. These definitions are given the attributes:

• packed - This attribute sets that no implicit padding should be inserted between members of the struct. For example:

  struct Foo {
    uint8_t a;
    uint64_t b;
  };
  

  Without the packed attribute, the size of Foo could be 12 or 16 bytes with 3 or 7 bytes of padding inserted between the members a and b. With packed, the two member variables will be back-to-back in memory.
• aligned(4) - This attribute ensures that the the size of the struct will be padded at the end to be a multiple of 4 bytes. It also makes the default alignment of the struct in memory 4 bytes as well.

In addition to these struct attributes, the struct definitions manually enforce 4 byte alignment for floating point values (i.e., float and double).

Endianness

Generally, functions in this library assume that serialized data is little-endian.

No special detection of conversion is done to enforce this, so external handling would be needed to use this library with a big-endian system.

Usage

All FusionEngine messages contain a MessageHeader followed by the payload of the specific message. To decode an incoming message you must:

1. Deserialize the header.
2. Validate the message by checking the CRC (optional).
3. Deserialize the payload indicated by the message_type field in the header.

For example:

#include <point_one/fusion_engine/messages/core.h>

using namespace point_one::fusion_engine::messages;

void DeserializeMessage(const uint8_t* buffer) {
  const MessageHeader& header = *reinterpret_cast<const MessageHeader*>(buffer);
  if (header.message_type == MessageType::POSE) {
    const PoseMessage& contents =
        *reinterpret_cast<const PoseMessage*>(buffer + sizeof(MessageHeader));
    ...
  }
}

See the message_decode example for more details.

Body Coordinate Frame Definition

The platform body axes are defined as +x forward, +y left, and +z up. A positive yaw is a left turn, positive pitch points the nose of the vehicle down, and positive roll is a roll toward the right. Yaw is measured from east in a counter-clockwise direction. For example, north is +90 degrees (i.e., heading = 90.0 - yaw).