Hui Fei Type
- 1 MTCB/MTCC Android Automotive Head Units
- 2 Manufacturers
- 3 Resellers
- 4 Links to MCU and Android OS firmware
- 5 Factory Settings "Passwords"
- 6 Rooting
- 7 Bootloader mode
- 8 System Dumps
- 9 Recovery
- 10 Latest MCU
- 11 Mods
- 12 Supported Hardware
- 13 FAQ
- 13.1 KNOWN PROBLEMS AND SOLUTIONS
- 13.1.1 Bluetooth problem
- 13.1.2 Losing radio station presets
- 13.1.3 Flashing MCU
- 13.1.4 Delay shutdown not working
- 13.1.5 Deafening Beeps upon start up
- 13.1.6 No element menu
- 13.1.7 Install apps from unknown sources grayed out
- 13.1.8 Insufficient memory to download an app even though there is plenty of free memory
- 13.1.9 Using the OBD II
- 13.1.10 Volume knob not working
- 13.1.11 Shows wrong door open
- 13.1.12 "SD Card is missing..." error
- 13.1 KNOWN PROBLEMS AND SOLUTIONS
MTCB/MTCC Android Automotive Head Units
The relationship between Chinese designers, manufacturers, brands, and resellers is not always clear. Based on wide similarities, but some obvious differences between units, it appears there are multiple manufacturers working from a common reference design.
These units are referred to as "MTCB" or "MTCC" head units, named after the developers - MTC, who also produce the (incompatible) "MTCD" head units.
They are often sold by sellers such as Eonon, Erisin, Pumpkin, Joying etc. When posting in the forums please DO NOT say things like "I have a Pumpkin XYZ00345" or I have an "Eonon 456GXL" - this will mean nothing to forum members you are requesting help from, please identify your unit by going into settings and pressing "about device", the 2 or 3 letter code before the MCU will tell you who makes your unit (see below). Please quote this at all times in the forums when identifying what unit you have. If this manufacturer code is not prefixed with "MTCB" or "MTCC" then you DO NOT have an MTCB/C head unit, if it is prefixed by "MTCD" then please visit the MTCD head unit page : http://forum.xda-developers.com/android-auto/mtcd-discussion-questions-development
One manufacturer - Klyde - substantially revised the MCU firmware and named it "MTCC".These "MTCC" MCUs are fully working on most MTCB units, but not all. The hardware is exactly the same as MTCB units, only the software is different.The latest ROMs from Klyde look for a "C" at the end of the MCU name and if its not there will not work properly. These later KLD 5.1.1 ROM updates ONLY work with MTCC KLD MCUs and the last version of MTCB (MTCB KLD6 v2.85). If an MTCC MCU, an MTCB KLD v2.85 or for MTCB units not made by Klyde, theres a way around it that uses Xposed to change the final MCU letter to "C" allowing later MTCC 5.1.1 + ROMs to work on units with non MTCC KLD MCUs (see here : http://forum.xda-developers.com/show...&postcount=810
The units commonly have a main board mounted in the bottom of the chassis which contains the MCU (microcontroller) which provides non-Android functions such as DVD, video/audio switching, radio tuner and front panel button support. A processor board (SoM - System on Module) containing the Rockchip SoC (System on Chip), RAM, flash memory, and an audio CODEC is commonly mounted behind the front LCD screen. It is this SoM which runs the Android OS.
The firmware is divided into two components, that which runs on the MCU, and the Android OS. These are usually distributed in "mcu.img" and "update.img" files. There are different versions of the MCU (e.g. KLD, KGL, JY, GS). These are associated with a manufacturer's specific implementation, and handle differences in button mapping, radio tuners, bluetooth modules, etc. In general, mcu.img files cannot be interchanged. MCU images are referred to using an abbreviation of the manufacturer's name. Some manufacturers have multiple MCU types (e.g. KLD, KLD2). In some cases, interchanging the firmware for these has appeared to work. Flashing the incorrect mcu.img is not known to cause any permanent damage, but the correct image may need to be flashed to restore proper operation.
The units are generally classified by manufacturer, processor (dual-core RK3066 or quad-core RK3188) and screen size (800x480 or 1024x600). The Android firmware is usually specific to a particular CPU/screen combination, e.g. RK3188/800x640.
Known manufacturers (and their MCU identifier) included:
- Joyous (JY)
- HuiFei/Kai Ge Le (KGL)
- Klyde (KLD)
- Kaiyide (KYD)
- Hot Audio (HA)
- RoadMaster (RM & YZ)
- Hansong Electronics (HZC)
- Cusptech (KSP)
- Unknown (BN)
- Unknown (GS)
- Unknown (KD)
- Unknown (KS)
- Unknown (LZM)
- Unknown (MD)
- Unknown (MX)
- Unknown (LM)
- Unknown (ZYC)
Links to MCU and Android OS firmware
booroondook also makes a custom ROM for MTCB, see here 
Coudu's ROMs are no longer being developed
Factory Settings "Passwords"
- 126 - factory settings menu
- 518 has been reported on some devices - factory settings menu
- m123456 - opens Factory Settings in "super" mode -- makes another option visible; Launcher type (a few option tabs not available in standard setup - including changing startup car producer logo, advanced audio settings, tuning the wheel control buttons, etc. Still, it's one of few useful codes)
- adbon - seems to enable adb on the usb port. Might enable it for all usb ports (haven't tested it yet)
- *#hct#root# - enables persistent root adb on usb port(s) (At least on some units with Android 5.1.1, it doesn't work. It shows 'HCT root' notification, but it doesn't work anyway)
- adboff - disables adb on usb port(s)
- keject - simulates the eject button for the DVD drive
- kpower - simulates the power button
- hcttouch - displays information about the touchscreen/calibration?
- hctbtup - some sort of bluetooth update mechanism?
- hctbtte0-9,0-9,0-9 - some sort of bluetooth testing code -- after the hctbtte there should be 3 digits, ranging from 0-9. Meaning unknown.
- sinotech - turn wifi on/off
- 5.1.1 : Type the code - *#hct#root# into the factory settings password box and press "ok", Install the latest version of King Root from their website , open the app and follow the on screen instructions, you need to have an internet connection and maybe some patience as it can take a while, or alternatively install a pre rooted ROM from the link below.
- 4.4.4 : Type the code - *#hct#root# into the factory settings password box and press "ok", or alternatively install a pre rooted ROM from here : 
- 4.2.2 : Files required:
- Root Master 1.3.6 - Mirror1
- Download the file above.
- Install the APK.
- Make sure you are connected to WiFi and you have an internet connection.
- Open Root Master
- Press the button that says Mulai Root. Chinese characters will flash across the screen for a few seconds
- A popup box will appear, press the "Root" button.
- More Chinese characters will flash across the screen.
- A second popup box will appear, press the purple button.
- You are now rooted. Its recommend you uninstall Root Master when finished. Also update SuperUser from the Playstore as this does not install the latest version.
This program connects to servers oversea sending hardware information. The downloads a script that will attempt to root the device. If the first script fails, it downloads additional ones. Future goal is monitor this communication with a data logger and find which script works, so that a unique program can be written to achieve root.
There is also a reported updated to Root Master at: Root Master 2.1.1 but this has not been tested on this device (update, it does work. When you install it, it asks you to update to an even newer version. Do not do it unless you can read chinese. The newest version has different options, all in chinese. Version 2.1.1 just has a button that says "root".) Version 1.3.6 worked on factory rom dated Feb 27, 2014
Holding the power button while turning on the unit will get you into bootloader mode. **This is battery power not acc power**
The screen will be black but plugging in a usb to the front usb will prompt the PC to install the RockChip bootloader drivers - this might help http://www.cnx-software.com/2013/11/08/simplified-method-to-install-rockchip-usb-drivers-in-windows-xp78/
The following are two different system dumps. One if splitting of the images from the factory supplied image. These files are untouched from there. The second is a rom dump of a rooted device. Hopefully from these we can find a better way to root, build a recovery made specifically for this radio. And find a way to unlock the bootloader.
- Press reset button and power button together
- After about 5 secs release reset button, but keep pressing power button
- When booting screen appears release power button.
- It boots into recovery.
- On the KGL-7650G - Power on (battery power) while holding power key without usb connected.
TWRP recovery TWRP recovery working perfect now thanks to Abdul_pt from Freaktab: LINK
You can download from here once you sign in: LINK
To enter stock recovery on Hotaudio units that have no hardware buttons see: http://forum.xda-developers.com/showthread.php?p=62624536#post62624536
On Xtrons this might work: 1) Hold power button until unit turns off and (on my unit) light flashes. 2) Let go and then press the power button again. This somehow shuts off the unit since it would normally just reboot after releasing the button it seems. 3) Press the power button again to turn it on. It should hopefully go into recovery.
I have no idea if this works on other units, but I have not seen a description of this in any of the posts/videos I have seen.
Note: Flashing the wrong MCU can lead to incorrect button mapping and/or no radio reception, however flashing the incorrect MTCB/MTCB MCU can usually be reversed by simply flashing a correct one, flashing an incorrect MCU from another unit type such as "MTCD" or a completely unrelated unit can result in a bricked unit. Before updating an MCU, make note of the version which is currently installed, and its Factory Settings. After flashing an MCU, you may need to reset the Factory Settings to their previous values. You should ONLY flash MCUs with the prefix ("MTCB or "MTCC") and manufacturer code (eg KLD, KGL, JY etc) that matches the version already installed, ie KLD MCUs only on KLD versions, KGL MCUs only on KGL versions etc the only exceptions are BN and HA versions which are interchangeable and some KLD MTCB units that can be upgraded to MTCC by flashing an MTCC MCU.
For MTCD/E interchangable/cross-compatible MCUs are HA, MLT, JY, KD, KGL.
BN-HA: 2.85 | GS: 2.73 | HLA: 2.67 | JY: 2.86 | KD: 2.81 | KGL: 2.83 | KGL1: 2.53 | KGL2: 2.53 | KGL3: 2.84 | KGL4: 2.53 | KGL5: 2.53 | KLD: 2.78 | KLD1: 2.77 | KLD2: 2.78 | KLD2B: 2.81 | KLD5: 2.77 | KLD6: 2.86 | KS: 2.68 | KSP: 2.68 | KSP2: 2.79 | KYD: 2.83 | LZM1: 2.08 | LZM2: 2.08 | LZM3: 2.08 | LZM4: 2.08 | LZM5: 2.08 | MD: 2.67 | MX: 2.82 | RM: 1.85 | RM1: 2.22
KLD5: 2.97 | KLD6: 2.97 | KLD9: 2.98
LM: 1.90 | LM: 1.98
HA: v2.71 | GS: 2.72
MTC Service - petrows
PCV Startup Builder - devilsoft
Xposed MTC - agentdr8
Malaysk Statusbar Mod - agentdr8
MTC Keys - MVG-V70
Xposed MCU - MVG-V70
MTC Volume - MVG-V70
Xposed Volume bar - 7floor
Modded MTC Apps
Bluetooth Red - Malaysk
Stock apps Red - Malaysk
JY Apps - Malaysk
Various apk mods - hadjistyllis
JY modded apps - sabruri1
Radio blue - Mat.
Launcher screenshots - Malaysk
SoM CPU: RK3066 (dual core) can be swapped with an RK3188 (quad core) board
Power button: Add a power button
Wifi/3G USB dongle: http://forum.xda-developers.com/showpost.php?p=60224687&postcount=11185
Front cam: Logitech C930e, Logitech C920
Bluetooth OBDII: ELM 327
Radio signal: Booster Amplifier. Buy antenna booster or power injector. Cylindrical shaped 'boosters' are actually power injectors and will only work if your car has a built in antenna booster, if it does not you will need an actual booster.
3G USB dongle not working: Check APNs. Install Mobile Network Settings
SD Card not working: Make sure formatted to FAT32. SmartDisk FAT32 Format Utility
Factory Settings Password (MCU Settings): 126
Root Access Password (4.4.4 Units, On Factory Settings prompt): *#hct#root#
TomTom not working: Steps (requires change to install-recovery.sh script)
KNOWN PROBLEMS AND SOLUTIONS
Losing radio station presets
- Every time a change is made in factory settings after the reboot, the presets will revert to the original default settings. ExposedMTC has a learn setting that for the most part will prevent this.
- Flashing the wrong MCU is known to cause the radio to stop working and the buttons to be mapped incorrectly. To prevent this, use the "Export" function in factory settings prior to updating the MCU, this will add an "MCU config" (mcu.cfg) file to your sd card card and the MCU settings will be flashed along with the new MCU.
Delay shutdown not working
- If the MCU is older than v2.5 the feature is not available. Otherwise check that the HU has constant power. There are reports that some ISO adapters are wired incorrectly.
- Some cars cut or drop voltage to the IGN (usually red) cable during cranking ('powering off' message then apps reset after engine starts) and engine shutdown (prevents the MCU from managing shutdown delay). Sometimes is fixed by adding a diode+capacitor solution
Deafening Beeps upon start up
- In factory setting under audio. Its the system sound setting. Turn it down.
- Factory setting - Other - RGB LED make sure set to RGB (will ONLY work if your unit actually has RGB LEDs)
Install apps from unknown sources grayed out
- Factory Settings - Other - unchecked Disable App Install
Insufficient memory to download an app even though there is plenty of free memory
- This issue appears to be a cache problem. There is only 1GB of space allocated for programs.
- First option is to uninstall several programs until you are allowed to install a program. Then install a cache clearing app.
- Second is to install a custom ROM such as a mildy modifed, pre-rooted ROM from @dsa8310, or a full custom ROM like @Malaysk's or @booroondook's, these all have at least a 2Gb app partitions.
- Third Option. Reallocate the partition size. here
- Malaysk's Roms can be found here
- This issue appears to be a cache problem. There is only 1GB of space allocated for programs.
Using the OBD II
- The OS is looking for a device named OBD if your reader has another name it will not connect.
- XposedMTC has a fix for this. Install Xposed Framework, then ExposedMTC
Volume knob not working
- Factory setting -other - disable Wheel3
Shows wrong door open
- Factory setting - other - disable rudder
- Rudder is so you can tell the unit if your car is right-hand drive or left-hand drive
"SD Card is missing..." error
- Due to the internal_sd not mounting. In Settings->Storage, if you find the internal_sd sd card and clicking on Mount doesn't do anything, erase it, and it should init to 11GB+ (depending on rom).