Vivacity UDP Occupancy Data Example

This example application listens for UDP packets on port 8000, and attempts to decode them as protobuf messages of vivacity.DetectorTrackerFrames

It prints the sensor ID and timestamp of each message it receives, and prints a table of zonal occupancies by class whenever these values change.

It is intended to be used as a starting point for developing a C application for consuming and processing Vivacity DetectorTrackerFrames eg on traffic signal controllers or UTC instations.

A dummy message sender application is provided for convenience.

Dependencies

• build-essential (or equivalent for your distro)
• protoc (3.11.4)
• cmake (3.15) (will probably work with lower if CMakeLists.txt is edited)
• python3

Submodules

Initialise and update the protobuffet submodule:

git submodule update --init --recursive

Getting started

First, create a Python virtual environment to work in and install Python protobuf in. This is needed by nanopb to be able to generate C source files.

python3 -m virtualenv venv
source venv/bin/activate
pip3 install -r requirements.txt

Then build the project:

mkdir build
cd build
cmake ..
make -j$(nproc)

Then run

./vivacity_occupancy_example

Generating C files manually without CMake

mkdir vivacity
cp -r proto-buffet/* vivacity 
./nanopb/generator/protoc --nanopb_out=. --plugin=protoc-gen-nanopb=./nanopb/generator/protoc-gen-nanopb -I. ./vivacity/**/*.proto

If generating manually, you'll need to set up your build system with vivacity in the include path, and to compile and link all of the generated *.pb.c files

Dummy Message Sender

Run this program to send dummy Detector Tracker Frame messages.

The program takes 3 arguments:

• -r rate: the rate at which to send messages. Measured in microsends between each message.
• -a ip address: the IP address to send the UDP frames to
• -p port: the port to send the UDP frames to.

For example: ./dummy_message_sender -a 127.0.0.1 -p 8000 -r 10000 will send the messages to the example decoder application at an interval of 10ms. This is equivalent to 10 sensors sending messages at 10Hz each