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diff --git a/en/devices/automotive/index.html b/en/devices/automotive/index.html new file mode 100644 index 00000000..83a7a6ef --- /dev/null +++ b/en/devices/automotive/index.html @@ -0,0 +1,109 @@ +<html devsite> + <head> + <title>Automotive</title> + <meta name="project_path" value="/_project.yaml" /> + <meta name="book_path" value="/_book.yaml" /> + </head> + <body> + <!-- + Copyright 2017 The Android Open Source Project + + Licensed under the Apache License, Version 2.0 (the "License"); + you may not use this file except in compliance with the License. + You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + + Unless required by applicable law or agreed to in writing, software + distributed under the License is distributed on an "AS IS" BASIS, + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + See the License for the specific language governing permissions and + limitations under the License. + --> + + + +<img style="float: right; margin: 0px 15px 15px 15px;" +src="../images/ape_fwk_hal_vehicle.png" alt="Android vehicle HAL icon"/> + +<p>Many car subsystems interconnect with each other and the in-vehicle +infotainment (IVI) system via various bus topologies. The exact bus type and +protocols vary widely between manufacturers (and even between different vehicle +models of the same brand); examples include Controller Area Network (CAN) bus, +Local Interconnect Network (LIN) bus, Media Oriented Systems Transport (MOST), +as well as automotive-grade Ethernet and TCP/IP networks such as BroadR-Reach. +</p> +<p>the Android Automotive hardware abstraction layer (HAL) provides a +consistent interface to the Android framework regardless of physical transport +layer. This vehicle HAL is the interface for developing Android Automotive +implementations.</p> +<p>System integrators can implement a vehicle HAL module by connecting +function-specific platform HAL interfaces (e.g. HVAC) with technology-specific +network interfaces (e.g. CAN bus). Typical implementations may include a +dedicated Microcontroller Unit (MCU) running a proprietary real-time operating +system (RTOS) for CAN bus access or similar, which may be connected via a serial +link to the CPU running Android Automotive. Instead of a dedicated MCU, it may +also be possible to implement the bus access as a virtualized CPU. It is up to +each partner to choose the architecture suitable for the hardware as long as the +implementation fulfills the interface requirements for the vehicle HAL.</p> + +<h2 id=arch>Architecture</h2> +<p>The vehicle HAL is the interface definition between the car and the vehicle +network service:</p> + +<img src="../images/vehicle_hal_arch.png" alt="Android vehicle HAL architecture"> +<p class="img-caption"><strong>Figure 1</strong>. Vehicle HAL and Android +automotive architecture</p> + +<ul> +<li><strong>Car API</strong>. Contains the APIs such as CarHvacManager, +CarSensorManager, and CarCameraManager. For details on supported APIs, +refer to <code>/platform/packages/services/Car/car-lib</code>.</li> +<li><strong>CarService</strong>. Located at +<code>/platform/packages/services/Car/</code>.</li> +<li><strong>VehicleNetworkService</strong>. Controls vehicle HAL with built-in +security. Access restricted to system components only (non-system components +such as third party apps should use car API instead). OEMs can control access +using <code>vns_policy.xml</code> and <code>vendor_vns_policy.xml</code>. +Located at <code>/platform/packages/services/Car/vehicle_network_service/</code>; +for libraries to access the vehicle network, refer to +<code>/platform/packages/services/Car/libvehiclenetwork/</code>.</li> +<li><strong>Vehicle HAL</strong>. Interface that defines the vehicle properties +OEMs can implement. Contains property metadata (for example, whether the vehicle +property is an int and which change modes are allowed). Located at +<code>hardware/libhardware/include/hardware/vehicle.h</code>. For a basic +reference implementation, refer to +<code>hardware/libhardware/modules/vehicle/</code>.</li> +</ul> +<p>For more details, see <a href="/devices/automotive/properties.html">Vehicle +Properties</a>. + +<h2 id=security>Security</h2> +<p>The vehicle HAL supports three levels of security for accessing data:</p> +<ul> +<li>System only (controlled by <code>vns_policy.xml</code>)</li> +<li>Accessible to app with permission (through car service)</li> +<li>Accessible without permission (through car service)</li> +</ul> +<p>Direct access to vehicle properties is allowed only to selected system +components with vehicle network service acting as the gatekeeper. Most +applications go through additional gatekeeping by car service (for example, only +system applications can control HVAC as it requires system permission granted +only to system apps).</p> + +<h2 id=validation>Validation</h2> +<p>AOSP includes the following testing resources for use in development:</p> +<ul> +<li><code>hardware/libhardware/tests/vehicle/vehicle-hal-tool.c</code><br> +Command-line native tool to load vehicle HAL and do simple operations. Useful +for getting the system up and running in the early stages of development.</li> +<li><code>packages/services/Car/tests/carservice_test/</code><br>Contains car +service testing with mocked vehicle HAL properties. For each property, expected +behavior is implemented in the test. This can be a good starting point to +understand expected behavior.</li> +<li><code>hardware/libhardware/modules/vehicle/</code><br>A basic reference +implementation.</li> +</ul> + + </body> +</html> |