xcertplay
An Android head-unit CarPlay receiver. It supports connecting to the MFi chip through a CH341 I2C bridge or directly through the board's I2C controller, and supports both wired and wireless CarPlay connections.
Features
- CarPlay host applications for Android and Android Automotive OS.
- Support for MFI chips connected through a CH341 bridge or native
/dev/i2c-Ndevices, local certificate/private-key files, and Remote MFI authentication (see the API below). - Wired and wireless CarPlay connections.
- CarPlay Ultra triggering (the protocol stack is untested/incomplete, but it can trigger the CarPlay Ultra prompt on an iPhone).
- Voice, navigation, and music multi-channel audio output mapped to the corresponding Android channels.
- Dynamic Activity resizing with automatic re-handshaking to the new resolution.
- Separate web pages for the main and instrument displays (the browser decodes H.264/H.265 directly; the main display supports touch and audio).
- Vehicle head-unit location reporting.
- Android 9 (API 28) support.
Usage
- Pair your iPhone with the head unit via Bluetooth.
- Before a CarPlay video stream starts, tap the Settings button in the lower-right corner. You can also swipe down with three fingers to open Settings.
- Make sure all the settings are configured as desired.
To enable another entry gesture, turn on
More gestures to Settings page. Start with one finger in the upper quarter of the left eighth of the screen, slide down along that strip, and lift in the lower quarter. - Scroll to the bottom and select
Save & Reconnect. - Connect your MFi chip using the method you selected.
- Wait for the connection to complete, then enjoy.
Web displays
- In Settings, under
Web displays, enableMain displayand/orInstrument display, set the resolution, then tapSave & Reconnect. - Put the browser device on the same LAN as the Android device and open the
address shown in Settings (
https://<IP>:8080/mainor/cluster, including the access key; it can be copied). - The certificate is self-signed: each browser warns once, choose to continue.
- Main display page: touch with up to two fingers; while it is open the phone's audio plays in the page. Tap the screen once to turn on sound (a browser requirement). The microphone stays on Android.
- The instrument display page is view-only and needs the iPhone to provide the second display stream.
Use a recent Chrome, Edge, or Safari. If the browser cannot play H.265, turn
off HEVC (H.265) in Settings.
Current progress
It works 👍. It has been tested on car head units and phones. If you encounter
an incompatible car head unit, please open an issue and attach your log from
/sdcard/Android/data/com.shilapi.xcertplay/files/logs/xcertplay.log.
Adapter board: CH341-to-MFI
Local MFI files
Choose Local files under MFI certificate & signing target, then use the two
Choose buttons to select the certificate and private key with Android's system
document picker. The supported formats are a DER PKCS#7 certificate (.p7b)
and its matching, unencrypted DER PKCS#8 private key (.pk8). The app validates
that the files match before starting the phone connection and reloads them on
MFI reconnect.
Store the private key in a protected location. Neither file is copied into app preferences; only Android's persistent read permission and document URI are saved.
Project structure
| Path | Purpose |
|---|---|
common/ |
Shared CarPlay host activity, settings UI, persistence, and app resources used by both targets. |
mobile/ |
Standard Android target using the shared CarPlay host UI. |
automotive/ |
Android Automotive OS target with the shared host UI and advanced audio channel mapping. |
shared/ |
Car App Library code plus the CH341, I2C, MFi, iPhone, iAP2, NCM, VPN, AirPlay, and media implementations. |
Remote MFI
The Remote MFi client treats a remote service as an MFi chip for remote calls, or uses BAA authentication. Remote authentication avoids the process of connecting to a local MFi chip for authentication.
Endpoints
| Method | Path | Purpose | Request body | Success response | Failure response |
|---|---|---|---|---|---|
GET |
/mfi/certificate |
Get the MFi chip version, certificate type, and certificate contents; cached by the client after the first call | None | Certificate JSON | {"detail":"..."} |
POST |
/mfi/sign |
Sign the challenge | {"challenge":"...","requestId":"..."} |
{"signature":"..."} |
{"detail":"..."} |
POST |
/mfi/reset |
Request a reset of the remote MFi chip | {} |
{"detail":""} |
{"detail":"..."} |
(Optional) Standard Bearer Authentication can be used for verification.
Currently, only BAA Authentication has been tested.
Requirements
- JDK 17 or newer to launch Gradle. The daemon resolves Java 25 through the Gradle toolchain.
- Android SDK Platform 37.
- Android 9 (API 28) or newer. On Android 9, Wi-Fi P2P 5 GHz mode is unavailable and LocalOnlyHotspot is used instead.
- Android NDK
28.2.13676358. - A physical USB Host/OTG Android device and MFi hardware are required for hardware validation.
Build
On Windows PowerShell:
$env:JAVA_HOME = "C:\Program Files\Android\Android Studio\jbr" .\gradlew.bat :shared:testDebugUnitTest :common:lintDebug :mobile:lintDebug :automotive:lintDebug :mobile:assembleDebug :automotive:assembleDebug
On macOS or Linux:
./gradlew :shared:testDebugUnitTest :common:lintDebug :mobile:lintDebug :automotive:lintDebug :mobile:assembleDebug :automotive:assembleDebug
Unsigned release APKs:
.\gradlew.bat :mobile:assembleRelease :automotive:assembleReleaseAcknowledgements
Thanks to LIVI for providing important reference for this project. Thanks to the showcase project for providing important reference for the BAA authentication in this project.
License
Licensed under the GNU General Public License v3.0.