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VHAL Emulator

Based on Google's VHAL Host Emulator.

vhal_emulator is a Rust library designed to simulate CAN bus communication with an Android Automotive system. The emulator leverages sockets and port forwarding through ADB (Android Debug Bridge) to facilitate communication between the emulator and the Android Automotive system.

Features

  • CAN Bus Simulation: Emulate CAN bus messages for testing Android Automotive Vehicle Hardware Abstraction Layer (VHAL) implementations.

  • Socket Communication: Utilize sockets for communication between the emulator and the Android Automotive system.

  • ADB Port Forwarding: Enable seamless communication by leveraging ADB port forwarding to establish a connection between the emulator and the Android device.

Usage

ADB Port Forwarding

First we need to connect to an Android Auto device running a Vehicle HAL with simulator. To do that, this library uses ADB port forwarding to a hardcoded remote port. Ensure that ADB is installed on your machine, or give the path to the directory containing the binary through the ADB_PATH environment variable.

You can let the library do the binding for you, using a random unused port on the host (note: currently, no device can be specified, so it binds as default device):

use vhal_emulator as ve;

let local_port: u16 = ve::adb_port_forwarding().expect("Could not run adb for port forwarding");
let v = ve::Vhal::new(local_port).unwrap();

Otherwise, you can manually forward the required port to establish a connection with the Android device, and then use it in the Vhal instantiation call.

    adb forward port tcp:0 tcp:33452      # random free port returned
    adb forward port tcp:12345 tcp:33452  # explicitely select the port to be used

Send and receive messages

Use the emulator to simulate CAN bus messages and test the VHAL implementation on the Android Automotive system.

Messages can be sent using the various helper functions that the library provides. Direct message manipulation is not allowed. For most general interaction, you can use set_property.

Receiving a message is done through recv_cmd, which returns an EmulatorMessage with an status field set, which allows to check for communication errors.

NOTE

recv_msg is a blocking call, so it may be desirable to set up a separate RX thread to handle any async messages coming from the device.

use vhal_emulator::vhal_consts_2_0 as c;
use vhal_emulator::VehicleHalProto::Status;

// Get the property config
v.get_config(c::VehicleProperty::HVAC_TEMPERATURE_SET).unwrap();

// Get the response message to get_config
let reply = v.recv_cmd().unwrap();
println!(reply);

// Set left temperature to 70 degrees
v.set_property(
    c::VehicleProperty::HVAC_TEMPERATURE_SET,
    ve::VehiclePropertyValue::Int32(70),
    c::VehicleArea::SEAT | c:VehicleAreaSeat::ROW_1_LEFT,
    None,
).unwrap();

// Get the response message to set_property
let reply = v.recv_cmd().unwrap();
println!(reply);

// Set the car gear to reverse
v.set_gear_selection(c::VehicleGear::GEAR_REVERSE).unwrap()

// Get the response message to set_gear_selection
let reply = v.recv_cmd().unwrap();
println!(reply);
assert!(reply.status() == Status::RESULT_OK);

Protocol Buffer

This module relies on VehicleHalProto.rs being in sync with the protobuf in the Vehicle HAL. If the VehicleHalProto.proto file has changed, update the file in the repository to generate an updated version. The update happens automatically at build time.

Testing

Test assumes there is a running AAOS VM. Again, make sure you also have ADB installed. Also, tests may interfere when run in parallel. To avoid false negatives, make sure you force a single thread.

$ ADB_PATH=/path/to/adb/bin cargo test --lib -- --test-threads=1

Regenerating vhal constants

File at src/vhal_consts_2_0.rs is autogenerated by the Python script at src/codegen/gen_vhal_const.py, and contains definitions for property ID, zone, and others, from the types.hal file. If the source file types.hal has changed, you can update the repository copy and use the script to regenerate the definitions.

To do so, you can use these commands:

$ make venv
$ source $HOME/.venv/vhal_emulator/bin/activate
$ make render
$ deactivate

Contributing

Contributions are welcome! Feel free to open issues or pull requests.

Please make sure your patches have all commits signed-up, and that you have passed fmt and clippy.

$ cargo +nightly fmt
$ cargo clippy --all-features --all-targets -- -D warnings -D clippy::undocumented_unsafe_blocks

License

This project is licensed under the LGPL-3.0-or-later License.

Files coming from the Android Open Source Project, are licensed under the Apache-2.0 license.

For more details, see the LICENSES folder.