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device-reveng

License CI

Rooting, reverse-engineering and replacing the software on a Choiceway / AiNavi "GT6-EAU" aftermarket Android 13 head unit (Qualcomm QCM6125), as fitted to a 2019 Toyota RAV4 (XA50).

Two things live here:

What it is
launcher/ Car Launcher — a Kotlin/Compose HOME launcher that talks to the car. Installable today; see Quick start.
HEAD_UNIT.md The research: EDL backup, TWRP + Magisk root, the MCU serial protocol, the reverse-camera stack, debloat.

Car Launcher home screen

⚠️ Read this first

  • This is personal research on hardware I own, shared in case it helps other owners.
  • Not affiliated with Choiceway, AiNavi, Toyota, Qualcomm or Magisk. All trademarks belong to their owners.
  • No firmware, ROM, MCU images or decompiled vendor sources are redistributed here. Only findings and original code.
  • Rooting can brick your unit. Flashing the wrong firmware or MCU image is a well-known way to permanently break these head units. Everything is provided as-is, with no warranty. The launcher itself does not require you to reflash anything — but it does need root for the car-integration features.

Does this fit my unit?

Developed and tested against exactly one configuration:

Value
Unit AiNavi / Choiceway GT6-EAU (XDA "Ainavi H6" family)
MCU RLC0_GT6E
SoC Qualcomm QCM6125 (ro.board.platform=trinket)
OS Android 13, API 33
Screen 1920x720 landscape @240dpi
Root Magisk (bootloader unlocked, SELinux permissive)

Check yours:

adb shell getprop | grep -E "ro.product.(model|device)|ro.board.platform|persist.sys.mcu"

Variant matters. A GT6-SE (MCU AT01_GT6SE) is a different unit. The Android ROM is broadly common across QCM6125 units, but the MCU image is manufacturer-specific — never flash another vendor's MCU.

The launcher degrades rather than crashes on a unit it does not recognise: without root or the vendor gateway it still runs as a plain HOME launcher, and the car-specific panels report themselves unavailable. If you try it on another unit, a hardware report is genuinely useful — including a negative one.

Quick start

1. Install the launcher

Tagged builds are published to armeehn/carlauncher-releases — a public, releases-only repo. Grab the latest APK there, then:

adb install -r carlauncher-<version>.apk

Once it is running, it can update itself: Settings → Updates checks that same repo and installs the newer build, so this is a one-time side-load.

Press HOME and pick Car Launcher. The stock launcher (com.szchoiceway.customerui) stays installed — this registers as an alternative home, not a replacement, so you can always switch back.

2. Run the Setup Doctor

Open Settings → Setup Doctor inside the launcher. It checks root, the vendor gateway, each special-access permission and the companion app suite, and prints the exact adb/su command to fix anything it finds. Start there rather than guessing.

3. Optional: grant the extras

Without root the launcher works, but reverse/steering-wheel/day-night events and SysVar writes are unreachable — those broadcasts are signature-protected and the vendor platform key is confirmed unobtainable. With root it picks them up automatically. Two grants are worth doing once:

adb shell pm grant com.ripostelabs.carlauncher android.permission.BLUETOOTH_CONNECT
adb shell appops set com.ripostelabs.carlauncher WRITE_SETTINGS allow

Upgrading from a build that was still com.reveng.carlauncher? The application ID changed to com.ripostelabs.carlauncher. Android treats that as a different app, so the new APK installs alongside the old one rather than upgrading it, and it does not inherit the old settings. Migrate deliberately:

# 1. In the old launcher: Settings -> Backup & restore -> Create backup.
# 2. Copy it off the unit BEFORE uninstalling anything.
adb pull /sdcard/Android/data/com.reveng.carlauncher/files/backups/
# 3. Install the new APK and set it as HOME, THEN remove the old one.
adb install -r carlauncher-<version>.apk
adb uninstall com.reveng.carlauncher
# 4. Push the backup into the new app and restore it from the same screen.
adb push <backup-file> /sdcard/Android/data/com.ripostelabs.carlauncher/files/backups/

Order matters: uninstalling the old launcher while it is your HOME app leaves the unit with no launcher until a new one is set.

Build from source

Requires JDK 17 and an Android SDK with platform 34. Nothing else — the Gradle wrapper pins Gradle 8.9.

git clone https://github.com/armeehn/device-reveng.git
cd device-reveng/launcher
./gradlew :app:assembleDebug

APK lands in launcher/app/build/outputs/apk/debug/.

./gradlew test              # JVM unit tests — no device or emulator needed
./gradlew :app:lintRelease  # lint
./gradlew :app:assembleRelease

Two things that bite:

  • Clone in full. versionCode is derived from git commit count, so a shallow clone would silently produce a wrong version. The build detects this and fails with an explicit message instead.
  • Release signing is optional. With the RELEASE_* environment variables unset, assembleRelease falls back to the debug key so the build still works out of the box. A debug key is generated per machine, so APKs from two different machines will not install over each other. See launcher/SIGNING.md.

The rav4-apps submodule holds 26 companion apps and is not needed to build the launcher. A plain git clone skips it; that is fine.

What the launcher does

Car integration goes through the vendor gateway com.szchoiceway.eventcenter over hand-written AIDL (CAR_API.md), with a root fallback for the signature-protected parts.

  • Home — dashboard, live car state, media, favourites, app drawer.
  • Motion awareness — parked-only locks driven by real speed, so text-heavy screens stand down while moving.
  • Media & radio — now-playing, transport, presets, band switching.
  • Climate — read-out from the CAN/MCU stream. Writes are deliberately not shipped.
  • Steering-wheel controls — the whole app is drivable from the wheel.
  • Notification shelf, on-screen keyboard, driver profiles, theming with an editor and import/export, Setup Doctor, backup/restore, and a CAN capture tool for further reverse engineering.

Honest status, including what is guessed and what is unvalidated on real hardware, is in launcher/README.md and STATUS.md. The radar byte layout in particular is unconfirmed.

Repo map

Path What
launcher/ The Car Launcher app (:app + :carlib)
HEAD_UNIT.md Root, EDL backup, camera and MCU findings, debloat
CAR_API.md The vendor car-integration API
OEM_SYSTEM.md Every OEM app decompiled: contracts, keys, and the replacement matrix
AIDL_ORDINALS.md Transaction ordinals for the vendor AIDL
LAUNCHER_DESIGN.md UI/UX spec and capability tiers
CUSTOMERUI_NOTES.md Stock launcher, decompiled — reference
CUSTOM_ANDROID.md Custom-ROM feasibility; why the platform key is out
ZLINK_NATIVE_ANALYSIS.md / CARPLAY.md Projection stack
can-integration/ CANable / LIN tapping plans and decoders
boot-speed/ Boot-time measurement and tuning
FINDINGS.md, STATUS.md Raw findings, live status
backup.sh, root.sh, debloat.sh, camera-diag.sh Runbook scripts

Runbook scripts

They expect the vendor files (Firehose loader, TWRP image, Magisk) in a workspace directory. That defaults to ~/rav4-headunit and is overridable:

RAV4_HOME=/path/to/workspace ./backup.sh

Each script checks its inputs up front and tells you exactly what is missing rather than failing halfway through. Sourcing those files is on you — see HEAD_UNIT.md.

backup.sh first, always. It is read-only and it is the only thing standing between a bad flash and a dead unit.

Contributing

Bug reports from other GT6 owners are the most useful thing. See CONTRIBUTING.md — the short version is: one feature per PR, never commit vendor material or device secrets, and say which unit you have.

Security issues: SECURITY.md.

License

Apache License 2.0. Third-party components and the vendor-interface carve-out are listed in NOTICE.