bledemoapp

Demo app using btleplug for BLE communication for android

Directory Structure

android - Demo app with 2 buttons. On clicking scan it will call function from rust library to start scanning bluethooth devices.

rust-android - Using jni to build dependencies.

rust-core - My rust library that uses btleplug for implementing BLE communication related functions.

scripts/install-android.bat will build the libraries and copy the SO files for android.

Getting Started

1. Installation process

• Install Node.js
• Install Rust
• Android Studio
• Install Android NDK - download android-ndk-r22b-linux-x86_64.zip and unzip it e.g.

NOTE: at time of writing you needed to use android-ndk-r22b or earlier, because later versions fail with an error like ld: error: unable to find library -lgcc. See rust-lang #85806 for more.

• Configure Rust for cross compilation:

rustup target add aarch64-linux-android
rustup target add x86_64-linux-android

(Note: aarch64 is for most physical Android devices, but x86_64 is useful for running an Android emulator on a PC. You can also add i686 if you use 32-bit emulators.)

Set linker to build so. files. Replace the path in rust-android/.cargo/config.toml.

[target.aarch64-linux-android]
linker = "NDK_HOME/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android30-clang.cmd"

[target.x86_64-linux-android]
linker = "NDK_HOME/toolchains/llvm/prebuilt/linux-x86_64/bin/x86_64-linux-android30-clang"

Replacing NDK_HOME with something like /path/to/android-ndk-r22b/.

2. Software dependencies

https://crates.io/crates/btleplug - Async Rust BLE library Due to requiring a hybrid Rust/Java build, btleplug for Android requires android\libs\droidplug-debug.aar generated by locally builing btleplug. (https://github.com/deviceplug/btleplug#android)

Build and Test

• Build shared object:

npm run build

This will create automatically...

./rust-android/target/aarch64-linux-android/release/libmylib.so
./rust-android/target/armv7-linux-androideabi/release/libmylib.so
./rust-android/target/i686-linux-android/release/libmylib.so
./rust-android/target/x86_64-linux-android/release/libmylib.so

(Plus some other files we don't need.)

...and copy the shared libraries into your Android project

./android/app/src/main/jniLibs/*