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USB DAC on AC8227

Hi, I was searching the net and did not find anything, so maybe android gurus here can help.
I have Tesla style head unit based on autochips AC8227 processor cortex a53 quad core processor. I have android 4.4.4 installed on head unit, despite the fact it says it's android 6.0. I've rooted it or it was rooted initially, do not know, however I have access to the system files.
So what I need^
1) I need the best way to make backup of the firmware in case I brick something manipulating with system files.
2) I need to be able to redirect whole sounds to external USB sound card in particular to USB DAC based on PCM2704 with SPDIF output.
from searching the net I found that if I enter commands in terminal emulator:
su
ls /dev/snd
I'll get all sound devices recognized and used by android system and there should be USB sound system listed as well (if it's recognized of cause) However external sound card is not there. So I need to add modules (drivers) for it into the system.
Where to get them and how to prepare to be usable with AC8227 processor I have no clue.
Please help me to find solution to my challenging questions.
thanks

Flyaudio G4xxxx - Intel Airmont Spreadtrum SC9853 8-core 1.8 GHz + 4GB RAM + 32GB fla

Flyaudio in Russia sells head units for a variety of cars that are also based on the Intel Airmont CPU, similar, but not equal to Joying latest Intel Airmont head units (see https://forum.xda-developers.com/an...ying-android-8-1-intel-airmont-eight-t3897206 and https://forum.xda-developers.com/an...ing-finally-head-unit-digital-output-t3891087 )
I purchased a G4909R unit, a 10 inch (=no knobs) unit for Volkswagen Passat B7 (https://flyaudio-shop.ru/products/g4909r-magnitola-android-volkswagen-passat-b7-2010-2015)
Youtube video https://www.youtube.com/watch?v=HZhE30W5ej8
Similarities to Joying’s units:
- Android 8.1.0 “user” build with its limitations for rooting, adb, debugging, etc.
- DSP with quite a lot of equalizer settings, but it seems to be a slightly different DSP
- FYT/SYU system apps (oh dear…)
Differences to Joying:
- No SPDIF audio output
- No 3G/4G modem
- Different BT chip
- Completely different form-factor (see video linked above at timestamp 6:06 https://youtu.be/HZhE30W5ej8?t=366 )
Passwords
Factory Settings: 3368
Developer Settings: 3368
Backlight current adjustment: 5768
Door lock interference: 0000
I was able to root it with the same approach (but not using the ready-made files!) as documented for the Joying units https://forum.xda-developers.com/an.../howto-root-joying-sc9853i-head-unit-t3915530
I noticed that some apps that I used on Intel Sofia and Rockchip PX5 units without problems now run into crashes on this unit, actually ANRs (Application Not Responding).
Actually, the Android 8.1 version on this unit is quite different compared to a “stock” Android 8.1, both from its UI and also “internally”.
SYU has created a monster of a Settings app. Car related settings and standard Android settings are all mixed without any structure. Not very clever at all!
Another Android modification: The steering wheel controls for PREV and NEXT only work when used in the SYU system apps (e.g. FM radio and Music player). No other standard app works, also not my DAB-Z app. Reason is that the FYT middleware is circumventing the Android framework MediaSession handling completely and thus the MediaControl interfaces in apps don’t work.
The SYU Bluetooth app still kills Google contacts, a bug that existed already 3 years ago in the Intel Sofia units with Android 6.01. They have not done anything about it!
My conclusion after some days with the unit on my desk, and now in the car for about a week:
Nice hardware, but the software is crippled more than ever…

realzoulou said:
Similarities to Joying’s units:
- Android 8.1.0 “user” build with its limitations for rooting, adb, debugging, etc.
I was able to root it with the same approach (but not using the ready-made files!) as documented for the Joying units https://forum.xda-developers.com/an.../howto-root-joying-sc9853i-head-unit-t3915530
Click to expand...
Click to collapse
Now that you have it rooted, you can make the /system read-writable from a rooted terminal.
Code:
su
mount -o remount,rw /system
Can you change the build.prop?
Code:
ro.build.type=user
to
Code:
ro.build.type=userdebug
and add:
Code:
persist.adb.tcp.port=5555
ro.debuggable=1
ro.adb.debuggable=1
And reboot?
Maybe you can then adb over tcpip?
I'm not sure whether this will work, but you can try.
On a normal user build adbd is not enabled/started. So it also might require the addition of "start adbd" in the "/system/bin/install-recovery.sh".
(But maybe when you set the debuggable properties, it is started automatically. I should take a look at the rc files in the boot image)

I enabled adb over WiFi persistently. However, it was a bit tricky.
1. Enable USB device mode in Developer Menu (very well hidden: First click on "..." on uper right corner, then the second option in the Chinese dialog)
2. Connect head unit to PC via USB (not all USB ports of the device allow adb, so try out all of them)
3. Use "adb shell" to execute
Code:
su
setprop persist.adb.tcp.port 5555
After a reboot you can connect via adb over WiFi.
The property ro.build.type is set usually by the kernel. You cannot set it via build.prop.

realzoulou said:
I enabled adb over WiFi persistently. However, it was a bit tricky.
1. Enable USB device mode in Developer Menu (very well hidden: First click on "..." on uper right corner, then the second option in the Chinese dialog)
2. Connect head unit to PC via USB (not all USB ports of the device allow adb, so try out all of them)
3. Use "adb shell" to execute
Code:
su
setprop persist.adb.tcp.port 5555
After a reboot you can connect via adb over WiFi.
The property ro.build.type is set usually by the kernel. You cannot set it via build.prop.
Click to expand...
Click to collapse
i know this is old, but...
I have adb over wifi enabled... when i connect to ADB i get device unauthorized. I shouldn't need usb drivers since its wifi, right? I am 99% sure its device related and not my laptop or software, because I have an 8227 headunit that connects fine. Is there anyway to authorize my TS9 Topway unit through terminal without root?

Question for Surfer or any other Android guru.

Is adb not able to connect over even see these Joying FYT Airmont units with Oreo on it?
The head unit has a switch to allow debug over usb but when I connect a usb to my laptop I don't get the dialogue screen on the head unit asking if I want to connect to this device and the laptop cannot see the unit at all.
I figured maybe it needed device specific drivers in Windows so figuring Joying hasn't made any I found universal usb drivers for it. Nothing.
I got an app called Naptime or something that's supposed to be able to put the unit in full doze. It's designed to work on rooted devices but also says that can be worked around by using adb to give certain permissions. I can't do that if I can't even connect adb to the damn thing.

Also, is rooting these using that Magisk method result in the same type of full root the normal way on other devices? It isn't limited compared to the normal way is it?

You can't use adb over tcpip on these units.
You can use adb over usb. You have to enable the developer options (tapping it 7 times). Go out, go in, and you have the adb over usb (OTG) option which does require an OTG cable.
@rigattoni posted in one of the SC9853i threads a step-by-step approach if my one-liner doesn't give you enough info.
rooted = rooted.
It doesn't make a difference in functionality whether the boot.img is rooted (called systemless rooting) or /system.
You always need an apk to "hand out" root rights, be it SuperSU, Superuser, Magisk or another.
In general the current systemless boot.img rooting is preferred. One of the big advantages is that it allows for OTA updates. But... we know that our units do not support that.
If you want to know more, just google for "systemless root" (sometimes "system-less root").
And I don't consider myself a guru. I read a lot and I have a good memory

surfer63 said:
You can't use adb over tcpip on these units.
You can use adb over usb. You have to enable the developer options (tapping it 7 times). Go out, go in, and you have the adb over usb (OTG) option which does require an OTG cable.
@rigattoni posted in one of the SC9853i threads a step-by-step approach if my one-liner doesn't give you enough info.
rooted = rooted.
It doesn't make a difference in functionality whether the boot.img is rooted (called systemless rooting) or /system.
You always need an apk to "hand out" root rights, be it SuperSU, Superuser, Magisk or another.
In general the current systemless boot.img rooting is preferred. One of the big advantages is that it allows for OTA updates. But... we know that our units do not support that.
If you want to know more, just google for "systemless root" (sometimes "system-less root").
And I don't consider myself a guru. I read a lot and I have a good memory
Click to expand...
Click to collapse
If the USB connection does not work for any reason, you could try the following:
Some units (as mine SC9853i) ADB can be used by WiFi, if you first run some commands on the unit.
You need a shell app and run these commands:
Code:
setprop persist.adb.tcp.port 5555
setprop sys.rkadb.root 1
reboot
After that you can connect via ADB from your laptop if both are in the same network.
Unfortunately that doesn´t work with all units.

rigattoni said:
If the USB connection does not work for any reason, you could try the following:
Some units (as mine SC9853i) ADB can be used by WiFi, if you first run some commands on the unit.
You need a shell app and run these commands:
Code:
setprop persist.adb.tcp.port 5555
setprop sys.rkadb.root 1
reboot
After that you can connect via ADB from your laptop if both are in the same network.
Unfortunately that doesn´t work with all units.
Click to expand...
Click to collapse
These commands require root

surfer63 said:
You can't use adb over tcpip on these units.
You can use adb over usb. You have to enable the developer options (tapping it 7 times). Go out, go in, and you have the adb over usb (OTG) option which does require an OTG cable.
@rigattoni posted in one of the SC9853i threads a step-by-step approach if my one-liner doesn't give you enough info.
Click to expand...
Click to collapse
Maybe I'm doing something wrong then. The developer options are enabled and I have it set for unlocked bootloader but my laptop can't see it whether I'm connected through the OTG usb port or the standard one and the HU doesn't give the popup dialogue asking if I want to allow the connection like my tablet and phone did. Maybe they changed something with these particular units with the new UI?
I did notice on another thread someone that had a FYT Joying Airmont with 8.1 and they said something about the 3 dot menu on the top right for "USB Connection" that brings up two options both in Chinese an his only worked on the lower option. I did try that too but still nothing. IDK. Maybe I had something else set wrong when I tried that lower option that made it not work in all my effort yesterday to get adb to see it and connect.

PX6 / MTCE / Android 9 / Extract Stock ROM

Hi there,
I got myself the following unit on aliexpress: https://de.aliexpress.com/item/4000805871840.html?spm=a2g0s.9042311.0.0.52ef4c4dBTvhGh. It has a CHS MTCE.
When I look at factory settings, it says "A-Media Auto" as device name.
It came with zlink Carplay PCB mounted on the PCB and worked with stock rom. When I changed to mod firmwares (e.g. HAL9k or Malysk) I actually lost the CarPlay functionality. zLink just stays at "waiting", however my phone identifies the unit as CarPlay available and connects over bluetooth using the carplay connection dialog. However the "use carplay now" dialog doesn't pop up. Manufacturer says, the unit would need to be returned to factory to reprogramme. Not sure this entirely the only option.
They said they don't offer the stock rom, just updates.
A friend of mine has bought exactly the same unit, so I was wondering if I could extract the OEM stock software from there and flash onto my unit. I am not an Android expert, however already changed a couple of iPhones/Tablets OEM software e.g. to LineageOS. So, with some turoials I normally find my way around. I am ok experienced on admin level on WIN and Linux.
Not sure the OEM Android is fully rooted, but I can find out, when I have the OEM unit in my hands.
Is there a (relatively safe) process to extract the stock rom and update the modded rom HU?

See my OTG thread, extract partition by partition from your friends unit, which you mention is the same, then flash your SOM.

Thanks for replying.
My SOM has an USB port soldered to it. (See photo). Chances are, I do not even use the "wire" method to connect, but just use this port?

wupperi said:
Thanks for replying.
My SOM has an USB port soldered to it. (See photo). Chances are, I do not even use the "wire" method to connect, but just use this port?
Click to expand...
Click to collapse
PX6 board has a HDMI connector on it - do you mean that?
I am also interested in a PX6 stock Android 9 partition export image, as I recently bought a PX6 board which has Android 10 preinstalled and therefore I am currently limited to it and can´t "downgrade" to my preferred ROM Hal9k v4 beeing Android 9 based...

SP7731E TS7.4.5-100 HU Root or how access USB debugging with PC?

Hello, I have chinese radio with these spec:
CPU: Quad-SL8141E
Android: 10
Hardware info: sc7731e_1h10_v1.1.0 (sometimes it says SC7731e... and in other places it states SP7731e..., not sure what I have )
MCU: Ts7.4.5-100-13-A2A39D-220104 (whatever that is)
I'm looking for a way to root it OR access radio through USB debugging. I need to resize my screen as screen nearby borders is very insensitive (I found this ADB overscan command).
I couldn't find any root for this device, or maybe I can't search, maybe you know something?
Other thing is that I don't have option to turn debugging over Wi-Fi, there's only USB debugging option in developer settings (engineer mode or something like that also doesn't include that option). So I bought USB cable with type A male on both plugs, but I guess that won't work because I can't see this device on my laptop. Like the head unit is in host mode or something, not device mode? Maybe that I can change to "device" so it acts like smartphone when connected to PC? Terminal emulator doesn't work, root required to enter adb commands.
I'm completely exhausted with this screen and unit, many options missing, although it's working fine.
Or maybe there is a way to extract rom image from this head unit, copy to pc, edit it on PC so it has root and then update head unit with "fixed" rom?