Spooler Controller

Introduction

This software is for controlling the cable driven parallel robot I built for my house. It uses DARTT over UDP to communicate with the actuators, which are using ESP32 bridges to provide networked communication to each of the actuators.

Comms Structure

The software uses UDP sockets to communicate with the actuators. This communication model should work well for distributed DARTT actuators - this software serves as a proof of concept for this architecture.

Building

Prerequisites (all platforms)

Clone with submodules:

git clone --recurse-submodules <repo-url>
cd spooler-controller

If you already cloned without --recurse-submodules:

git submodule update --init --recursive

Linux

Install dependencies:

sudo apt install build-essential cmake libsdl2-dev libgl-dev

Build:

cmake -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build -j$(nproc)

Run:

./build/spooler_controller

Windows

Uses the vendored SDL2 SDK in external/SDL/. Open in Visual Studio or build with CMake:

cmake -B build
cmake --build build --config Release

Android

Building for Android requires some one-time setup. You don't need Android Studio installed, but you do need the SDK and NDK.

1. Install Android command-line tools

Download the "Command line tools only" package from https://developer.android.com/studio#command-line-tools-only

Create a directory for the Android SDK and unpack the tools into it:

mkdir -p ~/android-sdk/cmdline-tools
unzip commandlinetools-linux-*.zip -d ~/android-sdk/cmdline-tools
mv ~/android-sdk/cmdline-tools/cmdline-tools ~/android-sdk/cmdline-tools/latest

Add to your ~/.bashrc or ~/.zshrc:

export ANDROID_HOME=~/android-sdk
export PATH=$PATH:$ANDROID_HOME/cmdline-tools/latest/bin:$ANDROID_HOME/platform-tools

Then reload your shell (source ~/.bashrc).

2. Install SDK packages

sdkmanager --install "platform-tools" "platforms;android-34" "ndk;26.1.10909125" "build-tools;34.0.0" "cmake;3.22.1"

Accept the licenses when prompted:

sdkmanager --licenses

3. Create local.properties

The Gradle build needs to know where your SDK lives. Create android/local.properties:

echo "sdk.dir=$ANDROID_HOME" > android/local.properties

This file is gitignored since the path is machine-specific.

4. Build the APK

Create the gradlew script if not present using:

cd android
gradle wrapper

Then from within the android directory, build using:

./gradlew assembleDebug

The first build will take a while because Gradle downloads its own dependencies and compiles SDL2 + the entire project from source for each target architecture (arm64, x86_64).

The APK will be at:

android/app/build/outputs/apk/debug/app-debug.apk

5. Install on a device

Connect your phone via USB with USB debugging enabled (Settings > Developer options > USB debugging), then:

adb install app/build/outputs/apk/debug/app-debug.apk

To see logs from the app:

adb logcat -s SDL/APP:V

Troubleshooting

• "SDK location not found": You forgot step 3. Create android/local.properties.
• NDK not found: Make sure the NDK version installed by sdkmanager matches what Gradle expects. Run sdkmanager --list --installed to check.
• Build fails with linux/if_packet.h error: The CMake Android block should define TCS_MISSING_AF_PACKET automatically. If not, clean and rebuild: ./gradlew clean assembleDebug
• App crashes on launch: Check adb logcat for the backtrace. Make sure your device supports OpenGL ES 3.0 (virtually all devices from 2015+).