Limewire

Limewire is a driver that facilitates communication between Synnax and Limelight. Check out the Limewire Design Doc for all relevant information.

Project Lead: Rohan Satapathy

Installation

How you install Limewire will depend on whether you're installing it in a development environment or on the DAQ PC.

Development Installation

1. Make sure you have Python 3.12 or greater installed.

2. Install uv, a project manager for Python. If you're on macOS, you can install uv with Homebrew using brew install uv.

3. Clone the repository and cd into the project directory.

   git clone https://github.com/masa-umich/limewire.git
   cd limewire

4. Install the project dependencies.

   uv sync
   uv pip install -e .

5. Install Ruff, a linter and code formatter for Python projects. If you use VS Code, you can install the VS Code Ruff Extension.

   All code submitted to this project should be formatted using Ruff before being merged into main. An easy way to do this is configure your editor to enable "Format on Save".

DAQ PC Installation

Limewire is installed on the DAQ PC using uv because it installs Limewire in a virtual environment while globally exposing the limewire command-line entry point. To download the latest version from GitHub, use the following command.

uv tool upgrade limewire

How to Run Limewire

Although Limewire is meant to run on the DAQ PC connected to the flight computer via Ethernet, there are three alternate configurations you can use that make it easier to test Limewire. In order from easiest/least realistic to hardest/most realistic, they are:

1. Limewire, Synnax, and FC Simulator running on your development machine
2. Limewire and Synnax running on the DAQ PC, FC Simulator running on your development machine, connected via WiFi
3. Limewire and Synnax running on the DAQ PC, FC Simulator running on your development machine, connected via Ethernet
4. Limewire and Synnax running on the DAQ PC, flight computer connected via Ethernet

Running the FC Simulator

To run the FC Simulator, you'll need to know how you're connecting to Limewire.

If you're using local Limewire and Synnax (Configuration 1), then your IP address will be localhost.

If you're connecting to the DAQ PC via WiFi (Configuration 2):

1. Make sure you're connected to the University of Michigan WiFi. If you aren't on campus, you can use the UMVPN service. If you need help getting this set up properly, contact Rohan Satapathy on Slack.
2. Find your public IP address. The method to do this varies based on your operating system, but you should end up with a IPv4 address that looks like 35.X.X.X. On macOS, the command to do this is ipconfig getifaddr en0.

If you're connecting to the DAQ PC via Ethernet (Configuration 3):

1. Log into the DAQ PC, go to network settings, and find the Ethernet IP address and subnet mask.

2. Find your development machine's network settings and ensure that the subnet mask matches and that the your computer's IP address is valid for that subnet mask.

   On macOS, this can be done by going to Settings > Network > Ethernet > Details > TCP/IP, set "Configure IPv4" to "Manually", then change the IP address and subnet mask.

   A simple strategy for making sure the IP address is valid is to take the IP address of the DAQ PC and incrementing the last octet by 1. Since there are only two devices in the network, this guarantees that there are no IP address conflicts.

Once you've determined your development machine's IP address, open a new terminal window and start the FC Simulator. Configure the number of seconds that the simulator sends telemetry messages for each client connection by setting the runtime argument.

uv run python -m fc_simulator [ip-address]:8888 [runtime]

You might receive a pop-up asking if you want to allow Python to accept incoming network connections. Make sure this option is enabled.

Running Limewire

If you're running Limewire on the DAQ PC:

1. Use ssh to access the DAQ PC, then enter PowerShell.

   ssh [username]@[daq-pc-ip-address]
   powershell

   To get the username and IP address of the DAQ PC, contact Rohan Satapathy on Slack.

2. Install the latest version of Limewire on the DAQ PC.

   uv tool upgrade limewire

   [!NOTE] If you're working on Limewire in a development branch, you can uninstall the mainline version and install Limewire from your development branch.

   uv tool uninstall limewire
   uv tool install git+https://github.com/masa-umich/limewire.git@your-branch-name

   After pointing the Limewire installation to the development branch, if you add new commits to your branch, you can easily upgrade Limewire using the following:

   uv tool upgrade limewire

   If you install a development version of Limewire, you MUST restore the mainline version of Limewire after you're done.

   uv tool uninstall limewire
   uv tool install git+https://github.com/masa-umich/limewire.git

3. Run Limewire.

   limewire [ip-address]:8888

If you're running Limewire on your local machine:

1. Open a new terminal window and start your local Synnax cluster using these instructions. I recommend using the Docker container method, but feel free to use any method that works well on your system.

2. Set LIMEWIRE_DEV_SYNNAX=1.

   Synnax has a limit of 50 channels without getting a license key, so LIMEWIRE_DEV_SYNNAX tells Limewire to only creates channels associated with the flight computer to avoid hitting that limit in order to enable local testing.

   On macOS/Linux:

   export LIMEWIRE_DEV_SYNNAX=1

   On Windows (make sure you're using PowerShell):

   $Env:LIMEWIRE_DEV_SYNNAX="1"
   

3. Run Limewire.

   uv run python -m limewire localhost:8888

Project Structure

This repository currently contains three packages in the src directory:

• limewire: The Limewire driver, a TCP client that runs on the DAQ PC and processes telemetry data from the flight computer.
• fc_simulator: The Flight Computer Simulator, a TCP server that acts as a stand-in for the Flight Computer while its Ethernet issues are being debugged, enabling testing of Limewire.