LCM-practice

This repository serves the purpose of practicing the Lightweight Communications Marshalling (LCM) library

Installation Instructions

Before starting anything, run the following commands

git submodule init
git submodule update

Installation Instructions - LCM

This is for linux (I run Arch, it should work on Ubuntu/Debian also. For Mac, windows, or others, check the documentation here

Before getting started, make sure the LCM repository is checked out to v1.4.0 (it should already be) To check this, run git branch -> you should see something like (HEAD detached at v1.4.0) If not, run git checkout v1.4.0

The following packages are required:

• build-essential
• libglib2.0-dev

The following packages are strongly recommended:

• default-jdk (or openjdk-9-jdk)
• python-dev

Run the following commands

cd lcm
mkdir build
cd build
cmake ..
make
sudo make install

Finally, run the following ... (This is for Arch, I am not 100% sure you need to do this for Arch/Debian. Check the link)

export LCM_INSTALL_DIR=/usr/local/lib
sudo echo 'sudo echo $LCM_INSTALL_DIR > /etc/ld.so.conf.d/lcm.conf
export PYTHON_VERSION=$(python -c "import sys; print(\"%s.%s\" % sys.version_info[:2])")
export PYTHON_USER_SITE=$(python -m site --user-site)
sudo echo "$LCM_INSTALL_DIR/python$PYTHON_VERSION/site-packages" > /usr/lib/python$PYTHON_VERSION/site-packages/lcm.pth

• note, I use pyenv to control python versions on my system, so I also added the site-packages location for my python 3.7.3 installation to /usr/lib/python$PYTHON_VERSION/site-packages/lcm .pth

Additionally, you may need to configure pkgconfig to find lcm.pc export PKG_CONFIG_PATH=$PKG_CONFIG_PATH:$LCM_LIBRARY_DIR/pkgconfig

Testing Instructions

First, setup the python environment To do so, it's best practice to maybe create a virtual environment python -m venv venv To activate it... . ./venv/bin/activate -> If you use some other virtual environment tool, go ahead and use that one

Now, in the directory with the setup.py file, run pip install -e . The package should now be pip install-able

LCM message types are created by first defining a *message*.lcm file that follows the format define here

To generate the proper bindings for python, run lcm-gen -p test_message.lcm as defined here

Then, to run the lcm test, just run python -m lcm_practice.send_and_receive and watch the output! (You might need to run this command in src/lcm_practice, but you shouldn't have to)