Android support/compatibility?

[cfiel]

Hi, this library sounds like it'd be very helpful for my project, but I'm wondering if it is compatible with Godot on an Android tablet? I would like to establish serial communication between my game running on an android tablet and a teensy microcontroller connected via USB. I do not see any mention of Android support on this github, so let me know if you think it'd work. Thanks!

[SujithChristopher]

Hey @cfiel , thank you for your interest! We haven’t thought about Android-based serial communication yet. How do you usually install the drivers on Android? Do you have any insights on that?

[Flavelius]

i'd like to be able to use it on android as well.
I see two ways in my case, but i haven't explored them in depth yet.
The first would be to use serial over bluetooth, which is out of scope for this repository.
The other is using an FT232 usb to serial adapter (connected via usb c otg). They are really cheap/affordable. This repository seems to provide android drivers for them: https://github.com/mik3y/usb-serial-for-android
With the upcoming godot-as-a-library changes there might be a way to just host godot in a regular android app and use the other driver.
But it would be very convenient if gdserial had an implementation for it as well.

Maybe some boards like the esp32 dev boards or arduino even enumerate as serial devices by themselves, in which case the serial adapter might not even be necessary.

[SujithChristopher]

Hi @Flavelius, thank you for your interest and for the detailed analysis! Android support is an interesting feature request. We'll investigate the feasibility further and see what's involved.

I'll leave this issue open as a future enhancement. Community contributions are always welcome if anyone has Android experience! 🙏

[Gotvna]

Android Support for GdSerial

This document outlines how to implement and use Android support in gdserial.

🏗️ Architecture

Android support is achieved through Rust Cross-Compilation. We compile the Rust code into .so (Shared Object) dynamic libraries for Android's primary architectures:

• ARM64 (aarch64-linux-android): Modern smartphones and tablets.
• x86_64 (x86_64-linux-android): Simulators, ChromeOS, and some tablets.

📝 Implementation Guide

To add Android support to this repository, you need to modify two files:

1. Update CI/CD Pipeline (.github/workflows/release.yml)

You need to add Android targets to the build matrix and ensureartifacts are copied correctly.

Add to the strategy.matrix.include section:

          - os: ubuntu-latest
            target: aarch64-linux-android
            lib_name: libgdserial.so
            use_cross: true
          - os: ubuntu-latest
            target: x86_64-linux-android
            lib_name: libgdserial.so
            use_cross: true

Add to the "Create addon release structure" step:

        # Create directories
        mkdir -p release/addons/gdserial/bin/android-arm64
        mkdir -p release/addons/gdserial/bin/android-x86_64

        # Copy artifacts
        cp gdserial-aarch64-linux-android/libgdserial.so release/addons/gdserial/bin/android-arm64/
        cp gdserial-x86_64-linux-android/libgdserial.so release/addons/gdserial/bin/android-x86_64/

Add to the "Supported Platforms" description (Optional):

          - Android ARM64
          - Android x86_64

2. Update Godot Extension Config (addons/gdserial/gdserial.gdextension)

Tell Godot where to find the Android libraries. Add these lines to the [libraries] section:

[libraries]
# ... existing entries ...
android.debug.arm64 =    "res://addons/gdserial/bin/android-arm64/libgdserial.so"
android.release.arm64 =  "res://addons/gdserial/bin/android-arm64/libgdserial.so"
android.debug.x86_64 =   "res://addons/gdserial/bin/android-x86_64/libgdserial.so"
android.release.x86_64 = "res://addons/gdserial/bin/android-x86_64/libgdserial.so"

---

🛠️ Building Instructions

Automated Build (GitHub Actions)

Once the changes above are pushed, creating a new release tag (e.g., v0.2.9) will automatically build and package the Android libraries.

Manual Local Build

To build locally using cross:

# Install cross
cargo install cross

# Build for ARM64 (Device)
cross build --release --target aarch64-linux-android

# Build for x86_64 (Simulator)
cross build --release --target x86_64-linux-android

The resulting libraries will be in target/<arch>/release/libgdserial.so.

⚠️ Important: Permissions & Restrictions

Accessing serial ports on Android is highly restricted.

1. Root Access vs. USB Host API

Standard Android permissions do not grant direct access to /dev/tty* device nodes (which this library uses via serialport-rs).

• Rooted Devices: If your application runs as root, it can access /dev/ttyUSB0, etc., directly.
• Non-Rooted Devices: You may not be able to list or open ports using the standard Linux file paths. Android requires using the Android USB Host API (Java/Kotlin) to request permission and get a file descriptor.
  • Current Limitation: gdserial uses the standard Linux serial backend. It does not currently bridge to the Android Java USB Host API. This means it will likely only work on rooted devices or custom Android builds (e.g., kiosks, embedded) that have relaxed permissions for the serial device nodes.

2. Android Manifest

Even for custom builds, ensure your export preset includes likely permissions if you modify the system to allow it:

• android.permission.USB_PERMISSION (if using USB Host)
• android.permission.WRITE_EXTERNAL_STORAGE (sometimes needed for device node access depending on mapping)

This is what i've found on internet

[Flavelius]

That reads like a weirdly half-baked ai answer, as it doesn't even seem to contain an answer to the main question of how to implement it, just how to integrate it. There's little value in posting this, as anyone can ask any chatbot anytime for a similar result.

[SujithChristopher]

Yep, adding it to CI/CD won't solve the issue.