yashsingh1/xdaforums huggingface dataset:
[MTCD Hardware Development] SkyBeam2048:
I know it's a while since I posted my last update here. But recently I felt like playing a bit with electronics again and did further investigations.

My initial tests with the RF210 module showed that bluetooth worked after swapping a unit with soldered BQ6 module to RF210 but I did not get any call audio.

I also figured my original BQ6 module had analog MIC input and Audio output. So I was not sure it's going to work. But I had a closer look at the schematics and traced some lines finding that both, analog and digital audio transfer is technically possible by using analog audio to the audio multiplexer chip.

However the RF210 module basically only featuring digital communication on RX/TX pins directly attached to the SOM. The RTS/CTS pins look to me like a serial interface. Indeed the used RTL8761BTV chip featuring UART along with some GPIO pins and I2C (SDA/SCL). So I was puzzled why I did not get any audio on my board as the audio should actually directly be mixed on Android in software and not sent as analog audio to the audio multiplexer. The PCM pins on the RTL8761BTV seem not to be used.

I also ordered another type of module called "BW124". Actually both modules are available here. To my surprise both modules (BW124/RF210) are based on exactly the same Realtek RTL8761BTV chip.

I found that on Android 10 (Hal9k Mod 5.0) I can select WQ_RF210 and BW124 but found that when I select FSC-BW124 it would fall back to MD725 after a reboot.

So I started to question the MCU software which is responsible for setting the right configuration. At this point in time my MCU was MTCE_KLD_3.01bd (sound patched). Just out of curiosity I have uploaded MTCE_HA_3.78. I did get the dreaded version unmatch message but to my surprise Bluetooth call audio started to work immediately.

So bottom line is that it is totally possible to change the bluetooth module. Worst case you might not have a header on your board and you might have to solder the module directly to BT_RX (SOM Pin 26) and BT_TX (SOM Pin 27) pins (of course also to some GND/5V supply).

It might be better just to connect those pins rather than just soldering in the rest of the pins too as the other pins might be wired differently.

But make sure also to upgrade your MCU (unless my sound-patched MCU actually caused the issue... I might need some more tests with stock MCU).

Edit: Tried the latest sound-modded MCU I could find (MTCE_LM_3.42bd) and also here there was no sound in calls. So perhaps sound mod is incompatible with Bluetooth calls.

Edit 2: I kind of confirmed this now. Could not find unmodded MTCE_LM_3.42 but installed presumably older but unmodded MTCE_LM_3.37 MCU and found Bluetooth audio to work fine. So somehow the sound mod seems to break Bluetooth audio.

Another side-effect I noticed was that the BW124 module did NOT work with MCU 3.37. I moved back to RF210 and it was working just fine. Even if both were selectable from factory settings it always reset to MD725 after reboot when BW124 was selected. So I guess support was introduced in later revisions only.
[MTCD Hardware Development] SkyBeam2048:
I even got some more info now I would like to share.

TLDR: My KLD unit is working with MD725 WiFi module and RF210 Bluetooth module on MTCE_HA CMU 3.78 but it required not just plain solering to the provided 11-pin header.

This weekend I tried to upgrade my car unit to Android 10 as I was doing some other maintenance work. Since it is a KLD unit equipped with MD725 I have done the same mod as my bench unit. By the looks of it both boards actually looked almost indistinguishable. But looking closer there were a few differences. My bench unit was equipped with WQ_BC5 (as far as I remember) and I did a successful RF-210 swap (see my previous post).

Solarding RF210 to my car unit header did not work. Measuring 5V on VCC showed 5V but dropped to 2V during bootup sequence. Well, I found that on this unit there must be some data transfer on the VCC line but it provided 5V before MCU initialization.

Also this behavior did not change no matter if using KLD 3.01 (latest KLD I could find) or HA 3.78 MCU.

The I2C bus on pin 3+4 on the header however were connected to the SOM and GND on pin 5 too. So I ended up soldering a cable from the nearby unpopulated 4-Pin header (presumably for a JST fan connector or similar to get solid 5V.

This seem to have worked just fine and RF210 looked OK and I could pair phones and OBD.

However after mounting everything I discovered that my unit will play an annoying beep tone during Android initialization. Also when Bluetooth devices are connected it would output some noticeable noise on the speakers. Mainly noticeable if nothing else is played. Removing RF210 again would also lower the noise level (yes those HTCx units are not specifically famous for their low noise level anyway).

So I discovered that the additional pins of the RF210 module were somehow connected to the audio system on this board. As mentioned earlier in this thread I was suspecting some boards to use additional pins for mic/audio analog output.

I suspect that my RF210 module RTS/CTS which match the BC5 LOUT/ROUT pins are routed to the audio multiplexer so what I was hearing was some digital communication pin connected to analog audio inputs.

The solution to this was to disconnect all pins except I2C RX/TX and GND as well as 5V. The module just working fine like this. But all other pins should not be connected. The noise level is back to normal when not playing any sources.

Another issue I faced was my WiFi immediately turning off automatically on HAL9k 5.0. Initially suspected issues with MD725 WiFi functionality but after re-installing Android 10 on latest HA release I could find it worked. So not sure what was the problem there.

So I think any unit could be upgraded. Worst case solering the module directly to the SOM and getting GND+5V from somewhere on the board should do it. But I wouldn't recommend this procedure to everyone.
[MTCD Hardware Development] brianmullen8:
I ordered the rf210, i installed the unit, upgraded from android 6 to 10, selected rf210 and it worked right away.
[MTCD Hardware Development] petttu:
Upgraded form PX5 to PX6 and replaced md7050 to rf210.

Just snipped off all the excess pins (soldered it to the board) and after changing the settings to rf210 worked straight away (even phone calls).

MCU version was MTCE_MX_V3.78_1
[MTCD Hardware Development] Mr.R™:
Anyone got a source for these in the UK? I've looked but can't find one and Marubox on Ali won't ship here apparently :/

EDIT: Have spoke to Marubox and they have updated their shipping options so it now ships to the UK again.
[MTCD Hardware Development] lancillotto71:
Good evening everyone, I have a Dasaita max 10 PX6 with MCU: mtce_ha_v3.67 bluetooth, I'm having trouble connecting the smart phone, how can I solve the problem?
[MTCD Hardware Development] marchnz:
Has the BT module been swapped and there is a problem?
[MTCD Hardware Development] lancillotto71:
Sorry...
[MTCD Hardware Development] lancillotto71:
Can anyone help me with the bluetooth that no longer works since I updated the mcu mtce_ha_v3.67? how can I solve this problem?
[MTCD Hardware Development] lancillotto71:
Hi

Angelor1​

, I wanted to know if this Bluetooth adapterhttps://www.amazon.it/gp/aw/d/B0899K77QJ/ref=ox_sc_act_image_1?smid=A11IL2PNWYJU7H&psc=1 works perfectly on the Dasaita with Android 10 and where should I connect it?... I assume to any USB port? or dedicated?
[MTCD Hardware Development] sev:
dumb question - i have the rf-210 soldered in and working on my XRC. I upgraded to Android 10 and it appears the bluetooth works good. But Its a bluetooth only module, what to use for wifi? md-725? Does it work?
[MTCD Hardware Development] marchnz:
YES
[MTCD Hardware Development] sev:
thanks! sorry that may have seemed obvious but years ago I had tried to remove my md725 off the main board and lifted a few pads and it was missing. For some reason I thought the rf-210 had wifi also.

Anyway I repaired the lifted pads and soldered the md-725 back in and now my wifi works.

Thank you
[MTCD Hardware Development] marchnz:
Looks odd, I wonder if it's an error in printing on the board. AGND is usually audio ground, but I don't see any [mic] or L, R.
[MTCD Hardware Development] switchboy:
I don't think this aproach is going to work since our boards are specificly designed to use the MD725. The MD725 uses USB to communicate and is solderd to an antenna at the other end. There would not be a need for manufacturers to also outfit the board for the connection type used by other WiFi/BT modules.

Our best shot might be to find another compatible USB WiFi/BT module which will probably have a completly different pinlayout compared to the MD725. But if we know the layout of the MD725 we could just run wires from the pads on our boards to the corresponding pads on whichever compatible WiFi/BT module we find. It won't look pretty, but in theory it should work.

The hardest part is finding a compatible USB WiFi/BT dongle. And if we have that we might save ourselves the soldering hassle and just use a USB splitter cable and extension cable and place the dongle somewere high behind the dash where te reception will be a hundred times better then from the SHARED WiFi/BT antenna which is located behind the headunit.

Just as a side note has anyone who has a MD725 version 1 tried to just replace /system/bin/gocsdk (be sure to give it 755 permission!) with one from android 9? It did not work for the MD725 version 2 in android 6 back in the day due to the fact that static linking was used so the binairy would not excecute. But the changes in architecture from 9 > 10 are much smaller so in theory this might just work. It did for SD-968 on android 9 by replacing /system/bin/sdsdk968 Maybe no one tried this aproach for MD725v1 because we failed with the MD725v2 in the android 8 days

https://nextcloud.gamesdust.nl/s/L3JnpqDzzr6tPfo the android 9 bin. but it is bit identical to the android 10 bin so something else is wrong.

init.hct.rc are both the same so that is not the problem either
[MTCD Hardware Development] marchnz:
I believe your assumption is incorrect.

Units with MD725 combined wifi/bt often do include provision for other BT module, which use serial comms. Mine does, and the others I have see do too, including the GS board I have and HA units I've seen posted here.

No need to replace the MD725 if changing BT. The MD725 for WIFI and the separate BT module is then used. This is how it works - check the schematic if unsure.

For those without the PCB pads, this suggested BT module could be wired in by identifying the relevant connections from the schematic.

I've suggested a source for the module, over to others to give it a go.

Regarding changing the vendor binary for md725, yes a few have tried from Android 6 to 8 and it doesn't work. You could try the Android 9 one, might be worth a shot. Regarding static linking, can you explain more?

Good thoughts. Id say give it a go :)
[MTCD Hardware Development] switchboy:
Checked the libraries on android 9 and 10 that gocsdk is depended on and they are different. So where probably changed and broke our driver. Swapping them with android 9 libs might mess up other stuff and require a reflash of the current firmware to fix it. Or it might magicly work haven't tested it since I own a MD725V2 which is certainly not going to work.

I don't have any soldering skills yet, planning to change that in the near future. One of my projects is going to be finaly changeing my type 2 to type 1.
[MTCD Hardware Development] switchboy:
As far as just soldering on a BC6 i apear to be SOL.

I might as well look for a different MTCD/E mainboard without PX(30 5 or 6) but i havent got any luck finding one on ali express. If anyone has a broken radio with working mainboard I am interested at this point

Edit:

So, I ripped off the pads while desoldering the MD725 module. I can hotwire the ground and 3.3v but I could not trace the two datalines so can't hotwire those sadly. Tried to use the MD725 v1 as a USB device. That worked for 10 minutes but in the end the chip decided that it did not like the 5V input after all and shorted.

Considering my options:

- Order another MD725v1 and solder in a voltage divider to drop the USB 5v to 3.3v and hope this ghetto solution is stable and then try to fix the software problem or otherwise be stuck on android 9 until google app makers drop support (which is going to happen before the end of the car's lifetime)

- Get my hands on another motherboard and hope/pray my screen and custom front with buttons can be transplanted. If I can source a unit with a broken screen or broken PX5 then is is probably the cheapest option but it is difficult and time consuming to source the parts since I can't seem to find the motherboard as a stand alone on AliExpress and dirt cheap broken units are not common on local second hand market sites in my area. (and as a rule lack a good description of the internal hardware)

- Upgrade to a PX6 unit and enjoy faster boot times, better radiochip and better amplifier. These units are still dirt cheap anyways and I found one shipping from within the EU. It is nice not to pay extra import taxes and have acces to warrenty

I chose the last option since the car in which this headunit resides is my daily driver and I don’t have a lot of free time to fiddle around right now. So don’t expect any more updates regarding a software fix from me any time soon. I might make a USB MD725v1 just for fun and giggles but not any time soon. (It takes at least 20-30 days for a replacement chip to be shipped from China)

Important lessons learned:

- Don't attempt SMD (de)soldering without a heatgun!

Even with my biggest soldertip and a copper wire wrapped around the soldered on PCB I just could not get all the solder points hot enough at the same time.

- Double check the input voltage on a board before assuming USB is USB so it is got to be 5v!
[MTCD Hardware Development] SkyBeam2048:
I did a bit more checking on my bench unit and used a scope on the L/R out pins and they do actually carry analog audio signals and seem to be wired up somewhere to the BD3702 chip.

So a direct swap of the modules won't work (at least assuming the Aliexpress module uses digital interfaces as indicated by silk-screening).

I don't know yet if I could somehow connect the BT module differently to the MCU or SOM and where.
[MTCD Hardware Development] marchnz:
Sorry to hear about your damaged board. I didn't have the same experience in damaging the board using good old desolder wick, I desoldered and carefully raised with a needle.

@Aaaron16 has kindly offered a unit that I can test on and aim to create a write up on. Very much appreciated @Aaaron16

It doesn't appear you have some of the BT module pads/options for the likes of a bc6 which could be reused, which would make the process more difficult.
[MTCD Hardware Development] SkyBeam2048:
I did have a look at some schematics and found the witson schematics which show a mic-switch and in the "mic_sel" circuit it shows the 10-Pin Connector presumably. This connector seems to be equipped with audio L/R and mic+/mic- connected to a switching circuit (74LVC1G3157GW) actuated by MIC-EN pin on MCU.

My RF210 module does not have any analog input/output but the 10-pin "MIC_SEL" connector seems also to use RX/TX pins connected to BT-RX/BT-TX on pin 27 (RX)/26(TX) on the SOM connector.

I didn't find any RTS/CTS pins but technically they are not strictly required and could be pulled to GND.

So there might be a chance to wire up the RF210 directly to the SOM. But I am not fully sure if I would perhaps get Serial/BT connection but it might fail to get mic audio during calls. However I noticed that the "MICIN+" connector on the mic switch might switch the microphone between SOM and the bluetooth 10-pin header. So either pulling the selector pin high or low might forward the mic input to pin 11 of the SOM connector. Technically allowing Android to process audio and forward it to the BT module.

Well, there is quite a lot of guessworking involved. So basically I would ignore RTS/CTS and just use RX/TX directly connected to the SOM and wire up 3.3 and 5V supplies to the module.

If I find the time to test it I will perhaps try it. However I guess this is not a mod we would be able to recommend to anybody as it's not a simple plug-in replacement. Some boards out there might have an unequipped 10-pin connector but one would have to individually check if it corresponds to analog-wired module (my bench unit claims to use WQ_BC5) or digital serial RF210 style interface. They are not easily interchangeable.
[MTCD Hardware Development] SkyBeam2048:
I was too curious and decided to do some soldering today on my bench unit with witson 10-pin connector:

Desoldered WQ_BC5 module from main board

Soldered in a socket for easy swap

Tested that the SDA/SCL pins of the WQ_BC5 module are actually linked to Pin 27/26 on SOM (BT_RX/BT_TX)

Soldered a connector just using RX, TX, 5V and GND to RF210 module, ignoring all other (analog audio/mic connectors)

Went into factory defaults and switched BT module type to WQ_RF210, restarted unit

I was pretty surprised that I could immediately pair my phone to the head unit without any problems. I also was able to use the A2DP app to play audio from the phone on my MTCE device with no problems at all.

Now the downsides: I was actually able to start and accept phone calls but no audio during calls on speakers and no mic audio transmitted to the caller on the other end either.

Perhaps the MIC output could be resolved with changes on the mentioned MIC switch IC to switch the MIC input to android system rather than putting it onto the pin going to the Bluetooth module (not connected). However I don't know about the speaker output. Speaker output from the phone should somehow be decoded by Android now (transmitted digitally on serial interface to SOM). And I do not have any clue yet how I can achieve this. Perhaps my device is also somehow muting Android audio output during calls as with the stock module the audio was mixed directly at the BD3702 chip. So I would need to find a way for my headunit to decode and play audio supplied via serial interface.

At least I believe I could use the RF210 module on my car unit; worst case soldering it directly to BT_RX/BT_TX of the SOM which would enable A2DP.

Also MD725 is a combined WiFi/Bluetooth module. So I guess here audio is already transferred using a serial or USB interface, so I might not hit the same problem about audio routing but I might run into problems having 2 Bluetooth modules in the system, one on USB and one on serial attached to SOM - but this might not be a problem on Android 10 where MD725 Bluetooth is not supported anyway.
[MTCD Hardware Development] marchnz:
Great work.

There is no need for the removal of the MD725, as you found, BT would continue to provide wifi.

Also as you found, BT selection is done via MCU/factory settings, selecting RF210.

I believe the last issues with BT mic and call audio is solvable. A later version schematic with this BT module would be helpful to see if there might be board level changes.

Very well done giving it a go, you're helping to develop a solution!
[MTCD Hardware Development] SkyBeam2048:
Also note that the WQ_BC6 module is available for sale on Aliexpress too. So people which do have the 10-Pin "witson style" header with analog input/output might be able to add this module to the unpopulated header.

So before ordering it might be required to clarify which module type might fit. Worst case is that none of them will fit also due to other unpopulated components on the main board.

However the WQ_RF10 module might be more easy to wire directly to the SOM as it requires only a serial RX/TX interface as well as 5V and GND.
[MTCD Hardware Development] abdelmonem:
Hello all

I'm switching from md-705 to RF 210, look at the picture below without problems, just for info, different printing on the board doesn't mean all BTs are using the same protocol when switching in factory setting, that will reconfigure all bin
[MTCD Hardware Development] marchnz:
I dont quite follow. Bluetooth module Pins are labelled differently between the two types.

Are you saying a direct swap worked for you or not?
[MTCD Hardware Development] abdelmonem:
yes exactly don’t care about what’s labelled in this board because it’s different hardware between Bluetooth 4.2 and 5 when you change in factory settings it will read new board , as you see I contact directly I didn’t change any bin

and also I test mic and BT audio and I was have problem fo internet via BT with old one ,now it’s solved, all functions working perfect

only 4 bin most by matching RX ,TX, GIND, 5.v or 3.3v or VDD or ACC all are same

if you want use it with usb for test also you will use this 4bin ,look in picture below
[MTCD Hardware Development] janusz12561@gmail.com:
Czy ten BT da się zamontować w tym miejscu na tej płycie GS?
[MTCD Hardware Development] abdelmonem:
yes it's compatible

here you can order

https://www.aliexpress.com/item/4001003523308.html?spm=a2g0s.9042311.0.0.2fce4c4dwW2boa
[MTCD Hardware Development] abdelmonem:
if any one need FC6000TN i can help ,chines seller thy not sell it separate but i can help for that also all version are compatible to most all mcu

already i made order when i get it i'll post here feedback about
[MTCD Hardware Development] janusz12561@gmail.com:
Kupiłem już. Czy znajdę gdzie opis, jak zainstalować?

Can I solder in the marked place on my BT board?
[MTCD Hardware Development] abdelmonem:
see picture i think it's same your motherboard
[MTCD Hardware Development] janusz12561@gmail.com:
Dokładnie tak samo, dziękuję.
[MTCD Hardware Development] marchnz:
English please.
[MTCD Hardware Development] abdelmonem:
Exactly the same, thank you
[MTCD Hardware Development] janusz12561@gmail.com:
BT is already installed and works great on "HCT4_px5_10.0_ota (20201216)"
[MTCD Hardware Development] abdelmonem:
great news please if you have picture of motherboard for help others
[MTCD Hardware Development] janusz12561@gmail.com:
As in post # 39, and my album is post # 35 without BT yet
[MTCD Hardware Development] abdelmonem:
Hello everyone

just now I finished test all bluetooth module available in Chinese market AliExpress or alibaba or other’s the best module is RF-210 test in 3 Different mcu working very good don’t try other modules you’ll loos your time

just one thing for future I attached bin connector to motherboard after that attach the module I didn’t solder direct to main board

all test with 10 or 9 bin in motherboard

For 12 bin I didn’t trying because I don’t have it but still you can send me picture of your main board and BT module I’ll try to find out

best regards
[MTCD Hardware Development] 0v3rdr1v3:
Deleted
[MTCD Hardware Development] didu73:
Hy

MY HU 5-6 year old MTCD px3 Android 5.1. I upgrade px3- px5 core board (som) and update old mcu HH-2.05 Cross compatible MCUs MX-3.30 work all components fine. I use Hal9k Android 9 rom. I want to update Hal9k Android 10 rom. But it won't work my bluetooth Md725 v1 (Android 9 work)

I want to replace it with a RF-210 module.

My motherboard only this 11 pin connector

I'm not very good at electronics

Could you help me?

Thx.
[MTCD Hardware Development] PolyKingo:
Hi, I had the same problem as you and I bought the RF210 module on AliExpress. I have soldered it, as indicated by "abdelmonem", without removing the other module that came in the radio, when I turn it on everything works fine but without any change or variation, I still get the MD725 as the Bluetooth module and I do not get the RF210. I'm still on Android 8.0, I haven't tried to upgrade yet.

Have you been able to do it without removing the old module?

Greetings and thank you!
[MTCD Hardware Development] marchnz:
This mod came about to support those wanting to change from Android 8 to Android 10.

It's unlikely that the driver/binary exists in android 8, do look in factory settings though.

Best try Android 10 and then changing BT type in factory settings.