"AN-21 U" - Unbranded 6.2" 2 DIN Pure Android 4.1 Car Stereo Radio Head Unit [ROOTED]

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Senior Member
Jun 4, 2012
I'm trying the impossible with this unit, to change the main board with a newer one, something with android 9 or 10, 2GB RAM, like those Rockchip RK-PX30 ones.
Does anyone found those type of boards?
My head unit is a Fiat Bravo one, the fw i use is is redmod 0.2.8 and MCU ver is (not sure about the mcu part, maybe i upgraded this one, i'm too lazy to go to my car).
Regards, pierre
View attachment 5431129
Is that even possible? I don't think it would be easy. It would need a rom with compatibility with all hardware of our unit, even if you manage to replace the board i won't be plug & play.

Well, let us know if you progress with this idea.


Mar 26, 2008
Is that even possible? I don't think it would be easy. It would need a rom with compatibility with all hardware of our unit, even if you manage to replace the board i won't be plug & play.

Well, let us know if you progress with this idea.
yes it's 100% possible.
i just received the new headunit erisin ES6971F and it's almost identical with 2015 AN21U.
what do I mean by identical? the metal case is identical except the backside, i had one broken screw inside the latteral bracket and i dismounted the old one from AN21u, it's identical, the metal case have mounting pins holes in the exact same position. the fron LCD support it's the same.
i guess adapting the newer motherboard with rockchip px5 it's simple, maybe some work at back side, front side as i said it's practically the same. of course the LCD is higher definition, but the plastic around the lcd is the same, the same 2 sdcard slots (one little modification, some suplementar miniusb connector for usb adapter on front panel.
but i'm just another consumerist EU idiot si i prefered the lazy approach, to buy a new one. and bravo for the chinese companies, they do the job my lazy europeans don't wanna do.


Senior Member
Jun 4, 2012
Hello, I have a problem. I installed the fullformat of 5 files, it took a while but it eventually finished ("update end"). After a while I manually restarted and now its stuck in the Android boot logo. Any idea?? Thanks guys


Senior Member
Jun 4, 2012
Ok, I understand that what's missing is a firmware now and I should install one. I'll follow first page to flash again the firmware:

Place the update files on your MicroSD card (see "Firmware Updates" section). Then turn the unit on whilst holding down the volume knob and home button. This should start the update process.
Last edited:


New member
Sep 5, 2019
Hi there!

Can anyone please help me to get my car audio into Developer Mode, I would like to do some updates as @heaky didI
My car is the SsangYong Tivoli

The software details are:
Model: SSangYong.AV
OS version : OS.15.01.28
Application Version: X100.15.DO.SOP.06.17
V850 Version: 115.12.01
IR Touch Version:
Framework Version : 15.02.12.R48

Thanks in adance


New member
Apr 6, 2022
My firmware is corrupted and the firmware mcu only updates . I try to make a factory reset or i try to use system aplications and the are closed.

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    "AN-21 U" - Unbranded 6.2" 2 DIN Pure Android 4.1 Car Stereo Radio Head Unit [ROOTED]

    "AN-21 U" - Unbranded 6.2" 2 DIN Pure Android 4.1 Car Stereo Radio Head Unit

    To avoid confusion, below is a picture of the unit this thread relates to.

    I am aware of a previous unit using the same design, but it runs an older version of Android. This thread is for the unit running 4.1 as standard.

    2013-10-27 16.19.46.jpg

    Specification / Features

    CPU: ARM Cortex A9 MST786 Dual Core 1GHz
    GPU: Mali-400 MP
    iNAND: SanDisk 8GB SD1N5C2-8G (1GB system storage, 6GB internal USB storage)
    Bluetooth: BlueCore5 CSR
    Screen: Capacitive 800*480
    GPS: SiRF Atlas V GPS Processor
    Radio: Philips TEF6624
    Sound Effect Processor: BD37534 ROHM
    Outputs: 4x 45w outputs, Toshiba TB2929
    Additional Outputs: 1x Subwoofer, 4x pre-outs
    Microphone: Built in microphone

    Supported Features
    Bluetooth connection to phone for calls.

    WiFi and 3G dongles. These must be plugged in before turning the device on, and are not hot-swappable.

    Compatible 3G Dongles
    • ZTE MF190 Clone (Qualcomm MSM6280 + RTR6280)
    • Huawei E171 (Qualcomm MSM6290)
    • Huawei E180
    • Huawei E261
    • Huawei E1752

    Non-Compatible 3G Dongles
    • Generic Orange/Black eBay dongle (Qualcomm MSM6280 + RTR6275)
    • Huawei E220
    • Huawei E352
    • Huawei E367

    Connection of multiple USB devices through a USB hub, including wireless keyboards, USB memory sticks, and wireless dongles. These types of devices are hot-swappable.

    Multiple USB memory sticks can be plugged in. They mount at "mnt/usb/sda1", "mnt/usb/sdb1", and so on. The limit is not known, three have been tested at once.

    Wiki Page

    This unit has a very useful Wiki page with a lot of good information.

    Tonghai Create AN-21 U Wiki

    It would be really appreciated if before posting any questions, you take a read of it, this main post, watch the video review, or do a search of this thread to avoid any repeats.​

    Video Review

    Other videos showing specific features are also available on my channel.​


    Download links and bugs section updated.​

    Root is now possible.​

    Previous News
    The manufacturer intends to add new features to the unit, they are currently developing an OBD II system, I assume this would be via USB. They say it will require additional hardware.

    Sooner than that, they plan to release wireless mirror link for Android phones.

    I asked about Bluetooth compatibility, they said my request would be sent to their engineer to include Bluetooth modules. Whether this actually gets included or not, we will have to see.​

    File Repository

    This site has links to most of the files in this thread, including firmware and MCUs.

    Android 4.1 Car Stereo File Repository

    All files are of course used at your own risk.​

    Firmware Updates

    To update the unit, extract the update files from the downloaded RAR and copy them to a MicroSD Card, insert the card, go to Settings -> General Settings -> System Update or turn the unit on whilst holding down the 'Menu' and 'Volume' buttons until the update starts.

    System Version 2.7.29
    Mirror 1 - Click here

    Previous Versions
    System Version 2.7.28
    Mirror 1 - Click here

    System Version 2.7.11
    Mirror 1 - Click here

    System Version 2.7.9
    Mirror 1 - Click here

    System Version 2.7.4
    Mirror 1 - Click here

    System Version 2.6.96
    Mirror 1 - Click here

    System Version 2.6.93
    Mirror 1 - Click here

    System Version 2.6.77-2
    Mirror 1 - Click here

    System Version 2.6.77
    Mirror 1 - Click here

    System Version 2.6.73
    Mirror 1 - Click here

    System Version 2.6.70
    Mirror 1 - Click here
    Mirror 2 - Click here

    System Version 2.6.68
    *WARNING* This update appears to cause issues with GPS *WARNING*
    Mirror 1 - Click here
    Mirror 2 - Click here

    System Version 2.6.62
    Mirror 1 - Click here
    Mirror 2 - Click here
    Mirror 3 - Click here

    System Version 2.6.60-2
    Mirror 1 - Click here
    Mirror 2 - Click here
    Mirror 3 - Click here

    System Version 2.6.60
    Mirror 1 - Click here
    Mirror 2 - Click here
    Mirror 3 - Click here

    System Version 2.6.40
    Mirror 1 - Click here
    Mirror 2 - Click here
    Mirror 3 - Click here

    System Version 2.6.23
    *WARNING* This update appears to cause unrecoverable bricking of the unit when changing model or MCU. *WARNING*
    Mirror 1 - Click here
    Mirror 2 - Click here


    "4.2.2" Versions
    Please note that these are actually Android 4.1, but the menu text has been changed to "4.2.2"

    System Version 2.7.11
    Mirror 1 - Click here

    System Version 2.7.22
    Mirror 1 - Click here

    System Version 2.7.26
    Mirror 1 - Click here

    System Version 2.7.26-2
    Mirror 1 - Click here

    System Version 2.7.26-3
    Mirror 1 - Click here

    Changelog (Unofficial)

    System Version 2.7.29
    • Unknown
    Previous Versions
    System Version 2.7.28
    • Unknown
    System Version 2.7.11
    • Unknown
    System Version 2.7.9
    • Unknown
    System Version 2.7.4
    • Unknown
    System Version 2.6.96
    • Unknown
    System Version 2.6.93
    • Unknown
    System Version 2.6.77-2
    • Unknown
    System Version 2.6.77
    • Unknown
    System Version 2.6.73
    • Unknown
    System Version 2.6.70
    • When changing panel keys or steering wheel controls, the notification bar is still displayed
    • New menu option for backing up and restoring both panel key and steering wheel control mappings
    System Version 2.6.68
    • Homescreen design reverted back to four large widgets per page
    • App icon for SWC settings
    • Setting in "Extra Settings" to force USB1.1
    • Factory reset is password protected (See FAQ)
    • Developer options are password protected (See FAQ)

    System Version 2.6.62
    • Bluetooth icon in notification bar (appears Bluetooth is turned on by default now, cannot turn it off)
    • Bluetooth menu, accessed via an app, has "SEARCH FOR DEVICES" and visibility option, however nothing functions when pressed
    • All extra applications removed (ES File Explorer, GPS Test Plus, QuickPic)
    • WiFi Hotspot can be activated without re-plugging the 3G dongle in
    • Background is winter-themed

    System Version 2.6.60-2
    • New home screen design
      2013-11-15 22.17.48.jpg
    System Version 2.6.60
    • Default applications changed back to original theme
    • APK Installer application install by default
    • Bluetooth renamed back to Phone
    • Screenshot feature now fixed and works correctly

    System Version 2.6.40
    • Larger notification bar
    • GPS icon removed from notification bar
    • Home, back, menu, and screen off buttons added to notification bar
    • Default applications changed to red theme (music player, radio, video player, phone)
    • Phone application renamed to Bluetooth
    • ES File Explorer installed by default
    • GPS Test Plus installed by default
    • QuickPic installed by default
    • Non-functioning screenshot featured added in settings menu

    Bugs / Issues


    Updated 2014.01.20
    Newest issues will be put at the top, solved issues, or issues with workarounds will be moved to the bottom.

    Unable to remove applications that are device administrators without factory reset due to security menu being disabled.

    Many applications are unable to "see" the MicroSD card, so the choice of music players is limited. The mount point is "mnt/usb/mmcblk1p1".

    Despite selecting "Front Speakers Only" for navigation sound, the sound comes out of the rear speakers too. Setting to "Front Right" appears to work correctly.

    Bluetooth is restricted to phones only. (Unsure if this is hardware or software related, talking to manufacturer suggests hardware limitation).

    Bluetooth dongles do not work.

    There is a "pop" from the speakers sometimes when changing applications that control sound, this is extremely obvious if you have a subwoofer installed. It happens when the unit is turned on, and when going from mute, to a volume level.

    Screen brightness when buttons illuminated is not user-configurable. This means it may be too bright or dark depending on the conditions. For example, when it is only mildly dark outside, and you have your lights on, the screen is very hard to see.
    Workaround: Enable constant illumination from the "Extra Settings" menu by setting the option to "CLOSE", this will set the keys to always illuminate. Then use an application such as Twlight to control the screen brightness based on sunset and sunrise.

    Random issue when downloading large applications. The progress will usually get to more than 50%, and then no progress is made.
    Workaround: The only fix I have found so far is to stop the download, reboot the unit, start the download, and repeat until download continues. It should download from where you cancelled. This appears to be caused by a limited download cache size.

    Steering wheel controls only work with default applications.
    Resolved: Open the radio (this does not appear to work with the music app), then hold the back arrow in the bottom right hand corner, the app will close, allowing steering wheel controls to function with other apps.

    Most recent default application always opens on boot and continues to play, even if paused. This includes the radio, music, video, and iPod applications.
    Resolved: Open the radio (this does not appear to work with the music app), then hold the back arrow in the bottom right hand corner, the app will close, and no default app will open on boot.

    USB Debugging is password protected.
    Resolved: The password is "[email protected]". Credit to @nikko82

    Screenshot feature does not work, when trying to save the screenshot, a save error appears.
    Resolved: This is solved in system version 2.6.60.


    Root is now possible thanks to help from some great XDA members.

    Credits to @WonderEkin for the Root My AN-21 U app and @bmj67 for supplying SettingsProvider.apk

    2014.06.06 - A new rooting tool named Baidu Root has been added to the repository. You can use this tool as an alternative to following the guide below.

    Files required
    Root My AN-21 U - [ Mirror1 | Mirror2 ]

    Root My AN-21 U has been updated since this video was taken, the app should now correctly show "Step 2".

    1. Download the required files above.
    2. Install Android Terminal Emulator on your unit.
    3. Open the AUX application and close it.
    4. Install Root My AN-21 U and create a link on the homescreen.
    5. Run Root My AN-21 U and press the "Step 1" button.
    6. Reboot the unit.
    7. Once the unit has rebooted the screen will likely be black, press the Home button to display the homescreen.
    8. Run Root My AN-21 U and press the "Step 2" button.
    9. Reboot the unit.
    10. Open Android Terminal Emulator and run the following commands.
      rm /data/local.prop
    11. Reboot the unit.


    Can I root this unit?
    Please see the "Root" section above.​
    HELP! My unit is stuck in a boot-loop!
    Place the update files on your MicroSD card (see "Firmware Updates" section). Then turn the unit on whilst holding down the volume knob and home button. This should start the update process.​
    Can I use Bluetooth OBD devices with Torque?
    Not at the moment, Bluetooth is only for phones and Bluetooth dongles do not work.​
    Does it have the full Play Store?
    Yes, it has the Play Store and all compatible applications are available for download.​
    What is the boot time?
    18 seconds to home screen, 22 seconds until music application starts. If you use the radio application rather than the music player, the radio sounds as soon as the unit receives power.​
    Where can I buy one?
    There are many listings on eBay/AliExpress under the search term "android 4.1 car", some have resistive, and some have capacitive screens. There is also the mention of a faster 1.2GHz dual core, however the unit actually has a 1GHz dual core CPU.​
    How good is the radio?
    The radio reception seems fine, as does the sound quality.​
    Is there a Wiki page?What is the USB Debugging password?What is the Factory Reset / Developer Options password?
    What is the Extra Settings password?
    Skinning/Modding AN21 system apps

    For all people who are interested to "skin" their AN21-U, I'd like to post some of my customizations:

    In general, it is super easy to change the appearance of the AN21 apps. Some experience with XML-based layouting programming languages such as Android, Java or WPF makes life easier but is not mandatory. I attached a detailed HOWTO below...

    A few words about my design thoughts: I tried to combine the red-themed flat style of the new Golf 7 infotainment system with Android JellyBean look&feel. Due to my blue temperature displays (-> first picture) I tried to reuse the same blue color in all system apps:

    Great VW boot animation, downloadable at i-cartech-forum.tk. Credit goes to raabi (YouTube video)

    Screenshot_2014-02-09-18-06-48.png View attachment 2617927
    ADW launcher with Car Widget & custom background
    Custom status bar without soft buttons (SystemUI.apk)

    Radio app: side note - even Radiotext is supported with this unit (not very common with chinese headunits)

    Equalizer, Zone settings

    Equalizer, Faders

    View attachment 2569467
    Phone app; I tried to use as much space as possible to avoid line breaks within contacts like in the factory design

    Phone app; Dialer

    I use Poweramp instead of the Music app; looks a lot fancier with the album covers

    Parking sensors (service app): I changed the car top view, colors and I also modified the smali code to display the range of my parking sensors correctly (outer sensors have less range than center sensors)

    HOWTO: Mod/Skin system applications
    Requires root access

    1.) Download apktool
    2.) Extract it to your hard disk
    3.) Copy the system app to modify (*.apk) from /system/app to an external USB stick
    5.) Copy the apk file to the location of apktool
    4.) Copy the apk to a different backup location (in case that something goes wrong)
    6.) Open command line and navigate to the location of apktool
    7.) Enter apktool d systemapp.apk (this will decompile the system app)
    8.) Change Icons and image resources (located in res/drawable-mdpi)
    9.) Change application layout (located in res/layout)
    10.) Rebuild the app by entering apktool b systemapp systemapp_MODDED.apk
    IMPORTANT STEPS (otherwise the modded app won't work on the unit):

    11.) Open the original systemapp.apk with a ZIP tool (such as 7zip) and extract AndroidManifest.xml and the META-INF folder to your hard disk
    12.) Open your newly generated app (systemapp_MODDED.apk) with a ZIP tool and drag AndroidManifest.xml and the META-INF folder to your app archive
    12.) Copy the systemapp_MODDED.apk back to your USB stick
    13.) Rename it back to systemapp.apk
    14.) Use RootBrowser on your unit to copy your modded systemapp.apk from the USB stick to /system/app/

    Those steps sound more complicated as they are. If you get some practise in modifying apps it actually takes about 1 minute...
    You can also use ADB over WIFI for grabbing and copying the system apps; In that case you have to ensure that you remount the /system partition as Read/Write (rw).

    Please be careful with editing the com.tw.service_a5a4.apk since this app handles all the communication with the MCU (so nearly everything). Coding mistakes will potentially cause constant crashes of the app, causing a modal popup to appear, which makes it nearly impossible to interact with the Android system then. I nearly destroyed my firmware with such a carelessness -> the only possibility then is to reflash a factory image. So please be careful, especially with this app.
    After a while something new from my side:
    I modded the system apps of 2.8.7 to look a bit more like Google's "material design" to harmonize better with current apps. In my opinion the chinese developers tend to add to much of everything, especially glossy buttons :D

    Anyway, here is the SystemUI with a thinner status bar without buttons and with white icons + text:

    Radio app:
    I actually like the layout of the Radio app.
    Moreover, I modified the smali code so that the radiotext always appears centered (that annoyed me a lot ;) ):

    The Equalizer:

    And the Phone app:
    View attachment 3020346

    If someone is interested in the APKs, find them attached. Simply copy the files into system/app and get the permissions right (or use RootBrowser for copying).

    BTW: Does anyone have the link to the post which described how to modify the phone app to display the contacts in alphabetical order? I know that there was a post in this thread, because I did that once (I think it was written by Nikko). However, I wasn't able to find the post with the forum search.
    MCU naming scheme

    --- snip ---
    Has anyone deciphered the MCU naming? I saw a few posts back that someone has.
    --- snip ---

    Ok here it goes... by disassembling one of the system files from 2.7.11, this is what I found:

    DISCLAIMER: This does not mean, that you can change the features in the MCU firmware by renaming the .zip files. You can change how they are presented in the model choose list, but the firmware will remain the same.
    This is purely for informational purpose, about how to identify the various .zip files. I take no responsibility for the accuracy of this information - Viewer Discretion Is Advised as they say.

    ... and before you ask - I don't know what all the features mean or do. The strings are copied from the source.

    Model Choose:

    This function looks for *.zip files in "/system/etc/mcu"
    Translates zip names into various information for model choose list.
    When selecting a model in the list, it unpacks the MCU file from the corresponding zip to "/data/tw/4bf18a00-297a-11e3-ab19-000c29ba27c0"
    ... and flashes it, I presume :fingers-crossed:

    File naming scheme:


    Translates to:
    "Car model(Version, Features, Audio chip, Tuner chip)"

    v = Version
    Used "as is" in building the model choose list.

    a = ?? (hardware revision perhaps ?!)
    (During model choose dialog creation, it looks like some value in the mcu is queried, and checked to be between 1 and 9999 (otherwise model choose aborts). Additionally [a] must match this value for the file to be included in the model choose list.

    bb(b) = Car model (default "Normal")
    Two or three digits. The two first digits are translated to the list below. A third optional digit translates to some additional feature.
    10 = VW
    20 = CRV/CIVIC
    22 = CRIDER
    30 = Camry/RAV4
    40 = Mondeo
    41 = Focus
    42 = F350
    50 = Mazda
    51 = CX5
    60 = IX35
    61 = IX45
    70 = Teana 2012
    71 = Teana 2013
    81 = Opel
    90 = PSA508
    F0 = V5
    F1 = X80
    xx1 = add "RZC" to features
    xx2 = add "HC" to features

    cc = Features (binary bitmask)
    bit 0 (.......1) = RDS
    bit 1 (......1.) = Sleep
    bit 2 (.....1..) = AD
    bit 3 (....1...) = 2Din FZ (bit 3 and 4 are mutually exclusive and mapped to some string array, no value exist if both bits are set)
    bit 4 (...1....) = 1Din FZ (bit 3 and 4 are mutually exclusive and mapped to some string array, no value exist if both bits are set)
    bit 5 (..1.....) = Color
    bit 6 (.1......) = BC6 (most likely code for BlueCore6 module, supporting OBDII - thank you @julsn; ref. #4009)
    bit 7 (1.......) = NODVD

    d = Tuner chip (default 0)
    0 = TEF662X
    1 = SI47XX
    2 = TEF665X

    e = Audio chip (default 0)
    0 = TDA7415
    1 = Rohm37534
    2 = TDA7719

    Some examples:
    4.2.15-1-10-2101 = "VW(4.2.15, RDS, Color, Rohm37534, TEF662X)"
    4.2.15-5-30-8001 = "Camry/RAV4(4.2.15, NODVD, Rohm37534, TEF662X)"
    4.2.15-8-10-E501 = "VW(4.2.15, RDS, AD, Color, BC6, NODVD, Rohm37534, TEF662X)"
    4.2.15-11-902-4501 = "PSA508(4.2.15, HC, RDS, AD, NODVD, Rohm37534, TEF662X)"

    Notice the numbers marked with RED ??
    As stated above, the .zip file will only appear in the model choose list, if this number matches the previously queried value from the MCU. It's probably some hardware revision check, to make sure you only flash an MCU that's compatible with the hardware you have. I don't know for sure though.

    So that's about all she wrote - have fun ;)


    31-07-2014 - Added information about BlueCore6 module. Minor layout change
    USB debugging password


    This is my first post here. I just received my unit, which I think is the same as discussed here, two days ago. I have discovered the password for USB-debugging, and as far as I can tell no one has posted that before. The password is "[email protected]".