April 24, 2024

Constructing an Android Automotive OS won’t be a tough process by itself, however the lack of excellent tutorials makes it exceptionally laborious. It solely will get more durable in case you don’t have at hand any specialised {hardware} like R-Automobile or Dragonboard. Nevertheless, you possibly can simply get a Raspberry Pi – a small ARM-powered, multi-usage pc and an ideal candidate to run AAOS. To make the method simpler for everybody combating this type of process, on this article, I’ll clarify step-by-step find out how to construct and run the most recent model: Android Automotive OS 13. 

Let’s get began! 

Stipulations 

To construct the system, you will want a Linux. You need to use WSL or MacOS (bear in mind, you want a case-sensitive file system), however pure Linux is the best choice. 

{Hardware} 

As within the earlier article, you want a Raspberry Pi 4B microcomputer, an influence adapter (or you possibly can energy it out of your PC with a USB cable), a reminiscence card, and a show. It’s good to have a touchscreen, however you should use your mouse and, optionally, a keyboard if extra handy. 

One other nice-to-have ingredient is a USB-TTL bridge for debugging. Discover my earlier article for extra particulars on find out how to use it. 

TL;DR; 

When you’re in search of the easy method, go to https://github.com/grapeup/aaos_local_manifest and comply with the readme. There are only a few instructions to obtain, construct and create a writeable IMG file on your Raspberry. However you want a couple of hours to obtain and construct it anyway. Warning! It might not begin in case you received’t modify the show settings (see beneath for particulars). 

Adjusting AOSP to make it AAOS 

This mission is predicated on Raspberry Vanilla by KonstaT – an excellent AOSP port for Raspberry Pi. It covers all the pieces you might want to run a pure Android in your Raspberry – an adjusted kernel, {hardware} drivers, and many others. Nevertheless, there isn’t a automotive construct, so you might want to assemble it. 

There are 4 repositories in github.com/grapeup relating to AAOS – three forks primarily based on Raspberry Vanilla and one new one. 

The repository aaos_local_manifest incorporates a listing of modified and new repositories. All vital modifications are situated in system/brcm/rpi4 and system/brcm/rpi4-car initiatives outlined within the manifest_brcm_rpi4.xml file. Within the readme of this repository, you’ll discover steps to clone and construct the mission.

The subsequent repository, aaos_device_brcm_rpi4, incorporates three components: 

The primary and most essential is to make the most of the brand new rpi4-car mission and take away conflicting gadgets from the bottom mission.  

Within the aosp_rpi4.mk file, there’s a new line  

$(name inherit-product, system/brcm/rpi4-car/rpi4_car.mk) 

to incorporate a brand new mission. 

Within the system.mk file, the product attribute is modified to automotive,nosdcard, and all customized overlays are eliminated, together with the overlay listing subsequent to the file. 

Within the manifest.xml file, the android.{hardware}.automotive.automobile HAL ({Hardware} Abstraction Layer) is added. 

The second ingredient is to configure the construct for the display I use. I needed to set the display screen decision in vendor.prop and set the display screen density in BoardConfig.mk. You most likely don’t want such modifications in case you use a normal PC monitor, otherwise you want another one on your customized show. Bear in mind that the system received’t begin in any respect if the decision configured right here is just not supported by your show. 

The final ingredient incorporates my regional/language settings in aosp_rpi4.mk. I’ve determined to make use of this file, because it’s not automotive-related, and to depart it within the code to indicate find out how to modify it if wanted. 

The principle half 

Probably the most main modifications are situated within the aaos_device_brcm_rpi4_car repository. 

The rpi4_car.mk file is predicated on system/generic/automobile/widespread/automobile.mk with few modifications. 

Conditional, particular settings for the Generic System Photos are eliminated together with the emulator configuration (system/generic/automobile/widespread/config.ini) and the emulator audio package deal (android.{hardware}.audio.service-caremu)

As a substitute, you want a mix of vendor-specific and board-specific parts, not included within the widespread/automobile makefile designed for an emulator. 

Android Automotive OS is strictly coupled with an audio engine, so you might want to add an automotive audio management package deal (android.{hardware}[email protected]) to make it work, even in case you don’t wish to join any audio system to your board. Additionally, AAOS makes use of a particular show controller with the flexibility to make use of two shows on the identical time ([email protected]), so you might want to embody it too. The subsequent half is SELinux policy for actual boards (not an emulator). 

BOARD_SEPOLICY_DIRS += system/generic/automobile/widespread/sepolicy 

Then you might want to add permissions to some pre-installed, automotive-oriented packages, to permit them to run within the system or consumer areas. 

PRODUCT_COPY_FILES += system/google/cuttlefish/shared/auto/preinstalled-packages-product-car-cuttlefish.xml:$(TARGET_COPY_OUT_PRODUCT)/and many others/sysconfig/preinstalled-packages-product-car-cuttlefish.xml

The subsequent part is EVS  – Exterior View System launched to AAOS 13. Even in case you don’t actually wish to join a number of cameras to the system to date, you need to embody the default implementation of the part and configure it to work as a mock. 

DEVICE_PACKAGE_OVERLAYS += system/google/cuttlefish/shared/auto/overlay
ENABLE_EVS_SERVICE ?= true
ENABLE_MOCK_EVSHAL ?= true
ENABLE_CAREVSSERVICE_SAMPLE ?= true
ENABLE_SAMPLE_EVS_APP ?= true
ENABLE_CARTELEMETRY_SERVICE ?= true
CUSTOMIZE_EVS_SERVICE_PARAMETER := true
PRODUCT_PACKAGES += android.{hardware}[email protected]
PRODUCT_COPY_FILES += system/google/cuttlefish/shared/auto/evs/init.evs.rc:$(TARGET_COPY_OUT_VENDOR)/and many others/init/init.evs.rc
BOARD_SEPOLICY_DIRS += system/google/cuttlefish/shared/auto/sepolicy/evs

The final half is to regulate variables for a system when operating. You set two system properties straight within the makefile (to permit a pressured orientation and to allow the AVRCP Bluetooth profile).

PRODUCT_SYSTEM_DEFAULT_PROPERTIES +=
    config.override_forced_orient=true
    persist.bluetooth.enablenewavrcp=false

Ultimately, you override the next system variables, utilizing predefined and customized overlays.

PRODUCT_PACKAGE_OVERLAYS +=
   
system/brcm/rpi4-car/overlay
   
system/generic/automobile/widespread/overlay

Usually talking, PRODUCT_PACKAGE_OVERLAYS permits us to overwrite any worth from a property file situated within the supply code. For instance, in our case the overlay root listing is system/brcm/rpi4-car/overlay, so the file system/brcm/rpi4-car/overlay/frameworks/base/core/res/res/values/config.xml overwrites properties from the file frameworks/base/core/res/res/values/config.xml.

Let’s dive into properties modified.

  • frameworks/base/core/res/res/values/config.xml file:
  • config_useVolumeKeySounds disables utilization of {hardware} quantity keys, as they aren’t current in our setup,
  • config_voice_capable allows data-only mode, as there isn’t a chance to make a voice name from our board,
  • config_sms_capable disables SMS capabilities for a similar motive,
  • networkAttributes and radioAttributes units the system to make use of WiFi, Bluetooth and ethernet connections solely, as there isn’t a GSM modem onboard,
  • config_longPressOnPowerBehavior disables long-press on an influence button, as there isn’t a energy button linked,
  • config_disableUsbPermissionDialogs disables USB permission display screen, because it shouldn’t be used within the AAOS,
  • config_defaultUiModeType allows the automotive launcher by default,
  • config_defaultNightMode allows evening mode because the default one.
  • frameworks/base/packages/SettingsProvider/res/values/defaults.xml file:
  • def_wifi_on allows WiFi by default,
  • def_accelerometer_rotation units the default orientation,
  • def_auto_time allows acquiring time from the Web when linked,
  • def_screen_brightness units the default display screen brightness,
  • def_bluetooth_on allows Bluetooth by default,
  • def_location_mode permits functions to make use of location companies by default,
  • def_lockscreen_disabled disables the lockscreen,
  • def_stay_on_while_plugged_in units the system to remain enabled on a regular basis.
  • packages/apps/Automobile/LatinIME/res/format/input_keyboard.xml file units the default foreground colour of the default keyboard, because the default one is just not very readable. Set keyTextColorPrimary and textColor parameters to regulate it.
  • packages/apps/Automobile/LatinIME/res/values/colours.xml units colours or image characters on the default keyboard and the letter/symbols swap on the underside proper nook.
  • packages/apps/Automobile/SystemUI/res/values/colours.xml units the background colour of the standing bar fast settings to make the default font colour readable.
  • packages/apps/Automobile/SystemUI/res/values/config.xml hides brightness settings from the highest bar, because it doesn’t work with no particular drivers for the show.
  • packages/apps/Settings/res/values/config.xml file:
  • config_show_call_volume disables quantity management throughout calls,
  • config_show_charging_sounds disables charging sounds,
  • config_show_top_level_battery disables battery degree icon.
  • packages/modules/Wifi/service/ServiceWifiResources/res/values/config.xml allows 5Ghz assist for the WiFi.
  • packages/companies/Automobile/service/res/values/config.xml disables operating a devoted utility when the system begins up or a driver is modified.

You may learn extra about every of these settings within the feedback within the unique information which these settings got here from.

The final repository is aaos_android_hardware_interfaces . You don’t want it, however there may be one helpful property hardcoded right here. In Android, there’s a idea referred to as HAL – {Hardware} Abstraction Layer. For AAOS, there may be VHAL – Car {Hardware} Abstraction Layer. It’s accountable, amongst others, for HVAC – Heating, Air flow, and Air Conditioning. In our setup, there isn’t a automobile {hardware} and no bodily HVAC, so you utilize android.{hardware}.automotive.automobile@V1-emulator-service whose default implementation is situated beneath {hardware}/interfaces/automotive/automobile. To vary the default items utilized by HVAC from imperial to rest-of-the-world, you might want to modify the {hardware}/interfaces/automotive/automobile/aidl/impl/default_config/embody/DefaultConfig.h file.

Constructing

The constructing course of for AAOS 13 for Raspberry Pi is far simpler than the one for AAOS 11. The kernel is already precompiled and there may be a lot much less to do.

Simply name these three instructions:

. construct/envsetup.sh
lunch aosp_rpi4-userdebug
make bootimage systemimage vendorimage

On a Home windows laptop computer (utilizing WSL, after all) with the i7-12850HX processor and 32GB RAM, it takes round 1 hour and 40 minutes to perform the construct.

Making a bootable SD card

There are two choices – with or with out the mkimg.sh script. The script is situated beneath system/brcm/rpi4 listing and linked in the primary listing of the mission as rpi4-mkimg.sh. The script creates a digital picture and places 4 partitions inside – boot, system, vendor, and userdata. It’s helpful as a result of you should use Raspberry Pi Imager to write down it into an SD card nevertheless, it has a couple of limitations. The picture at all times has 7GB (you possibly can change it by adjusting the IMGSIZE variable within the script), so that you received’t use the remainder of your card, irrespective of how massive it’s. Moreover that, you at all times want to write down 7GB to your card – even when you need to replace solely a single partition, and together with writing zeros to an empty userdata partition.

The choice method is to write down it on the cardboard by hand. It’s difficult beneath Home windows as WSL doesn’t comprise card reader drivers, nevertheless it’s handy in different working methods. All required information are constructed within the out/goal/product/rpi4 listing. Let’s put together and write the cardboard. Warning! In my system, the SD card is seen as /dev/sdb. Please modify the instructions beneath to not destroy your knowledge.

OK, let’s clear the cardboard. It is advisable to wipe every partition earlier than wiping your entire system to take away file methods signatures.

sudo umount /dev/sdb*
sudo wipefs -a /dev/sdb*
sudo wipefs -a /dev/sdb

Now let’s put together the cardboard. This line will use fdisk to create 4 partitions and set flags and filesystems.

echo -e "nnnnn+128Mnantn0cnnnnnn+2Gnnnnnn+256Mnnnpnnnwn" | sudo fdisk /dev/sdb

The final step is to write down knowledge and put together the final partition.

sudo dd if=boot.img of=/dev/sdb1 bs=1M
sudo dd if=system.img of=/dev/sdb2 bs=1M
sudo dd if=vendor.img of=/dev/sdb3 bs=1M
sudo mkfs.ext4 -L userdata /dev/sdb4
sudo umount /dev/sdb*

Abstract

Android Automotive OS is a huge leap for the automotive trade. As there isn’t a manufacturing automobile with AAOS 13 to date, you possibly can expertise the longer term with this guide. What’s extra, you are able to do it with a low-budget Raspberry Pi pc. This manner, I hope you possibly can develop your functions and play with the system simply with out an extra layer of utilizing emulators. Good luck and pleased coding!