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How to connect two android devices over USB

First, why:
I own two Coby Kyros tablets that I am using as a part-time car headrest entertainment system. Heck, they are so cheap, buying a dedicated car video just does not make sense.
Tablets work great for that purpose, great resolution (for a car), have games and music. There is only one piece that is missing, simultaneous video playback on both tablets.
Getting this working presents two challenges:
* A fast, stable, always ON connection between the tablets.
* A master/slave video playback software, either streaming or syncing
Glad to report, I've solved the first issue, that I'll describe here. Be warned this is not for the faint of hart and right now is fully manual. If you find it helpful I might work on automating the link.
Tested on Froyo. At least one device has to be rooted and support the USB Host mode.
Now, how:
The idea is simple - use the android debugging bridge to forward TCP ports between two systems over USB. If you do have USB tethering enabled on at least one device (I did not) you could use RNDIS to route all traffic, not just specific ports, over USB.
1. Pick a tablet to be the slave. It must be rooted. Get the adb client compiled for android from here, upload it to the slave /system/xbin ("adb push ...") and make executable (adb shell chmod 755...). Get ConnectBot from the market to access its console.
2. Put the slave into the USB Host mode, disable USB debugging on it. Put the master into the USB device mode and enable USB debugging.
3. Connect the master and the slave using a miniUSB-USBfemale and USBmale-miniUSB combination, a USB hub (make sure it is a high-speed one) or a miniUSBmale-miniUSBmale cord.
4. Now the tough part, typing shell commands on the tablet. You can make it a bit easier by using a USB hub and connecting a keyboard and a mouse together with the other tablet to the slave.
On the slave start ConnectBot for the localhost and type the following
Code:
less /proc/bus/usb/devices
Look for your master's devices BUS# and DEV#. Record both. Note, these numbers change when you re-plug USB.
Now, on the slave:
Code:
su
mkdir -p /dev/bus/usb/001/
ln -sf /proc/bus/usb/[BUS#]/[Dev#] /dev/bus/usb/001/001
5. Test. On the slave run 'adb devices'. It should show your master in the list.
6. Forward slave ports to the master as needed. Run 'adb forward tcp:123 tcp:234'. Now you can use localhost:123 on the slave to reach out to the master port 234 over USB.
If your kernel is RNDIS enabled you could route all network connections over the usb0 interface, essentially creating a one-to-one network. Stock Kyros unfortunately does not support RNDIS so I've not tested it.
The ADB USB speed is not bad, averaging 2.5MB/sec after protocol overhead.
I did some research on the second issue, went several routes (mplayer, VLC and UPNP) and, sadly, found nothing that currently works. If you know of any working video source/sink pair or a sync peer for android, let me know.

sicvolo said:
Tested on Froyo. At least one device has to be rooted and support the USB Host mode.
Click to expand...
Click to collapse
Is there a guide on getting USB Host Mode to work on this device or if there isn't could you write one?

I have two Galaxy S3. I went through steps 1-3, all fine. But in step 4, there is no '/proc/bus/usb/devices'; there are only '/proc/bus/input' and '/proc/bus/input/devices'.
Is there any other method to get dev# and bus#? Thanks.

[Q] Non-branded Android car device - 3g modem problem

It is my first post here, so forgive me any mistakes. I'm a newbie to Android.
I've been drifting throughout the Internet and XDA-developers forum to find a solution to my problem, but I can't find it. You are my only hope. Even original support can't help. I bought a non-branded Android device for my car in April 2014, specifically this one: (happyshoppinglife[.com] / honda-civic-android-autoradio-dvd-navigation-with-dtv-wifi-3g-p-1168[.html]). Since then I can't connect to the Internet using 3G modem.
It seems to have some tailor-made Android version, since normal tablets don't have a DVD or FM radio or wheel-buttons.
Recently the manufacturer/developer upgraded the Android to a version 4.4.2 (chinabatemon [.com] / cargpss / android-update-442.rar)
Precisely it is:
Model SNT-210
Android 4.4.2-0140516-sntb-HOMEMADE
Kernel 3.0101-gdaab9de-dirty
[email protected] #9
Build omnisntb-eng 4.4.2 KOT49H eng.QDroid.20140516.133512 test-keys
iGo 9.6.7.235654-Thin1.1
Manual: autoradiodvdgpstv [.com] / user-manual / car-dvd / android-car-dvd-player-cp1.pdf
Currently I have 3g modems: Huawei E220 (VID 12d1:1003, PID 12d1:1003), Huawei K3770 (VID 12d1:14d1, PID 12d1:14c9), ZTE MF626 (VID 19d2:2000, PID 19d2:0031), Huawei E230 (VID 12d1:1003, PID 12d1:1003)
Wifi works fine, but I need 3g..
[EDIT]
I have no root access:
1|[email protected]: / $
after doing "su":
[email protected]: / $
I'm probably unable to root the device because I cannot connect to it (I got a cable: USB type A - USB type A, but it didn't work: no response from Android device nor from my laptop). After clicking "Build number" once (in the "About CarDVD" menu) it shows "No need, you are already a developer", but there are no "developer options" in the Settings menu.
There is the app "3g reconnect" already installed in the system, but after I connect a modem (E230, E220 or K3770) with working SIM (no PIN) in "Plus" (MCC 260 MNC 01) its LED is blinking green, and then blue after a while (one blink per 3-5 sec) but the system remains unchanged. The support (the Chinese via chat, not very nice experience talking: an hour waiting for response) said I .
I tried PPP Widget to help me, as well as Android Terminal and Slick USB 2 Serial Terminal.
I set PPP widget to start manually, set APN to "internet", left number to dial unchanged, no user, no password. After booting without 3g modem, PPP Widget starts and I connect the modem to a USB port. I click on the PPP icon, choose my E230 modem (12d1:1001) and I click connect. PPP Widget searches for the port and tries to connect.
When I turn on logging, portcheck.log says:
== START LOG ==
PPP Widget version 1.3.3
USB_ModeSwitch log from {date}
Raw args from udev: 1-1.1/portcheck
using top device dir /sys/bus/usb/device
SymLinkCheck called with /sys/bus/usb/ttyUSB0
My name is ttyUSB0
Checking my endpoints ...
in /sys/bus/usb/devices/1-1.1/1-1.1:1
checking ep_81 ...
ep_81 has interrupt transfer type
--> I am an interrupt port
--> No interrupt interface below me
{something was here}
== END LOG ==
When I check the Android Settings (Mobile status) there is:
Network: unknown
Signal strength: 2147483647 dBm 255 asu
Mobile network type: Unknown
Service state: Out of service
IMEI: {my SIM's IMEI}
IMEI SV: Unknown
IP address: Unavailable
WiFi MAC address: {some MAC address}
When I turn Android Terminal it goes:
lsusb:
Bus 001 Device 001: ID 1d6b:0002
Bus 002 Device 001: ID 1d6b:0001
Bus 001 Device 002: ID 05e3:0608
Bus 001 Device 003: ID 0bda:8176
Bus 001 Device 007: ID 12d1:1003
Bus 001 Device 005: ID 04e8:6860
Sometimes There is Bus 001 Device 005 instead of 007 by 12d1:1003
When I try to use Slick USB 2 Serial Terminal it connects to the modem and answers all the AT commands:
ATI
Huawei
E230
Rev. 11.104.20.00.00
IMEI...
+GCAP: +CGSM +DS +ES
AT+CSQ
15.99
AT^SYSINFO
2,3,0,5,1,,4
AT+COPS=?
(1,"Plus","PLUS","26001",0), (2,"Plus","PLUS","26001",2) ... {and other}
AT+COPS?
0,2,"26001",2
I can swich the modem's mode:
AT^U2DIAG=0
the default was AT^U2DIAG=257
After switching to AT^U2DIAG=0 the modem seems to be recognised by lsusb as 12d1:1001
I tried to connect manually:
AT+CGDCONT=1,"IP","internet"
ATD *99***1#
.. and it returned CONNECTED
but when I went back to the home screen and tried to check if there is Internet access (I turned on Chrome), there was no Internet access, but I have to revise this once more.

hi i'm italian and my english is bad, i've buy your same model but i have some problems because i've a short manual only for radio,bt,cd parts.
i want a complete manual to understand the several application infact i don't know which is the app for 3g, if is it possible to use logo of car, why when connect my phone (samsung s5) with bt when download the contacts remain in working without finish.
if i can help me, it is wonderful
thank you in advance
by
alfonso

3g problem => APN list & rooting problem
alfo79 said:
hi i'm italian and my english is bad, i've buy your same model but i have some problems because i've a short manual only for radio,bt,cd parts.
i want a complete manual to understand the several application infact i don't know which is the app for 3g, if is it possible to use logo of car, why when connect my phone (samsung s5) with bt when download the contacts remain in working without finish.
if i can help me, it is wonderful
thank you in advance
by
alfonso
Click to expand...
Click to collapse
HI, alfonso.
Answering to your questions:
1) I've had many problems, which I had to solve mysfel or using chat-support (It was not a pleasant experience, each talk lasted forever..)
2) There is no "a complete manual" for SNT-210. I can only share the one I got from Happyshoppinglife => Manual
3) Changing logo: there should be an application to do that, but in my case the user should enter a password, which was "121212" and could choose the logo for your car
4) I had the issue with downloading the contacts from my phone via BT either. I didn't resolve it, I just quit doing that (downloading contacts). The problem was probably too much records in the phonebook. But synchronising the Android's phonebook with Google Account might be a solution. But.. there is a 3g / wifi connection required, which I still don't have.
Sholud you have any more questions, don't hesitate to write.
Regarding the 3g connection problem:
I am still struggling with the 3g modem case. I found out (thanks to arnoldziq) that my 3g modem is ok (there are modem drivers in Android 4.4.2, Android finds the modem and the usb port the modem is attached to). All the problems may result from a wrong APN list in \system\etc\apns-conf.xml. In my case there is
Code:
<apn carrier="PlusGSM" mcc="260" mnc="01" apn="internet" type="default,supl" />
but it should be
Code:
<apn carrier="Plus" mcc="260" mnc="01" apn="internet" type="default,supl" />
But the next problem is - it is not editable (the device is not rooted). And I tried to root the device using a shor tutorial by an XDA user KID52 for a similar device. I connected both: the device and my laptop to a router so that both devices see each other (ping confirms that). I installed ADB ("15 seconds ADB v1.3.exe" from here) on my laptop. Then I tried to connect. In my cmd (laptop) I run:
Code:
C:\Users\Grreg>adb connect 192.168.170.3
* daemon not running. starting it now on port 5037 *
* daemon started successfully *
unable to connect to 192.168.170.3:5555
C:\Users\Grreg>adb devices -l
List of devices attached
C:\Users\Grreg>adb tcpip 5555
error: device not found
I tried to install adbWireless.apk in the CarDVD device and run the commands again. Without chnage. I read that in order to use adb via Wifi / TCPIP you have to be connected with an USB cable. But I tried, and I can't do it - neither device noticed the connection with USB type A plug - USB type A plug cable.
A question to XDA users: is there an alternative way to root the device? Or am I doing something wrong?

Hi, thank for your assistance
now I'm having another problem, the car is connected to an external display, if I insert a USB stick containing a movie in automatic start a program to read music only, if I use an app for Android naturally from the external screen is impossible see anything ... is there a way to watch movies from usb directly with some programs of the car without using the app of android?
In fact there is a program for dvd....a program for aux in....a program for usb and a program for sd card (this last I have not used yet, infact I don't know is a program for music or movies ...I hope the second!!)
You know something about?
Scuse me for my bad english
thank you

alfo79 said:
Hi, thank for your assistance
now I'm having another problem, the car is connected to an external display, if I insert a USB stick containing a movie in automatic start a program to read music only, if I use an app for Android naturally from the external screen is impossible see anything ... is there a way to watch movies from usb directly with some programs of the car without using the app of android?
In fact there is a program for dvd....a program for aux in....a program for usb and a program for sd card (this last I have not used yet, infact I don't know is a program for music or movies ...I hope the second!!)
Click to expand...
Click to collapse
Hi,
what do you mean by "external display"? my device (youtube.com/watch?v=sEJMvUQhTJA) does not provide an option to connect an external screen - no DVI/HDMI output (maybe some AUX out, but I did not check that) - what would you need one for?
After iserting an SD card (or connecting a USB plug with SD reader or USB Flash memory) Android autimatically turns on a music app, but if you want to watch a movie, just close it and browse to the sdcard / flash using for instance "ES File Explorer File Manager" (I had it preinstalled), then when you see your file, click on it and choose an app you want to opent the file with, MX Player is one of the most popular (I had it preinstalled). is that what you needed?

i have your same software but the car device is different, i can connect an external display for person behind for example, but if i use an app of android to red movies on usb the external display doesen't receive nothing; infact if i use dvd ,or tv connet on aux ,i riceive them on external display.
Is strange that automatically device usa a program only for music fo usb or sd card....is not possible to instal a program (no app android) for use them to see movies?

I found a Russian forum where they've been discussing about this device, there is a lot of information and they are way ahead of us, the URL is
4pda dot ru/forum/index.php?showtopic=578873
you can find the latest firmwares for this device here
pan.baidu dot com/share/link?uk=1529874287&shareid=2934645460#dir/path=%2FCUSP%2FCSDVI-4.4.2[/url] ,
the Malay version always seems to be released first, and instructions on how to update can be found here
cusptech dot com/index.php?c=service

Unstable connection with Xbox 360 wireless controller

I'm trying to get my Xbox 360 wireless controller and wireless receiver (Chinese knockoff that works perfect on PC) I had laying around to work with my OPO. Sadly this has been harder then I expected. I have ran into the following problem. After I reboot my phone and the receiver is connected through a OTG USB cable, my controller is connected to my OPO and I can move in menus and play a SNES game for example. The problem however is that this connection remains for a very short amount of time, it seems that the phone stops seeing the USB device that is connected. When trying other USB devices this problem does not occur, I tried a USB stick and a USB mouse. Once the connection is lost the only way to regain connection is to reboot the phone.
I have no idea why this is happening
I've tried many settings and tested a lot of stuff:
I followed the steps in this thread: http://forum.xda-developers.com/showthread.php?t=1792531
I also messed around with other product ID settings related to xbox 360 controllers: http://www.linux-usb.org/usb.ids
On my Windows 7 PC I used USBview.exe to see with which ID the receiver/controller combination was identified which was: 045e 0291 (Microsoft Xbox 360 Wireless Receiver for Windows)
I used the app USB Device Info to see if my OPO was detecting anything via the OTG cable. As mentioned above after a few seconds ~ < 1min it just disappears.
I've searched in general with Google and specifically on XDA and the OPO forums but I've not found a similar problem with regards to the disconnection problem.
Anyway, if someone here has experience with wireless xbox 360 controller on the OPO or USB devices that disappear. Help would be appreciated!
I think I might have found why this will not work correctly, the default kernel of the OPO doesn't have xpad.ko.
Alex240188 said:
The problem is that there are no drivers for the Xbox 360 control pad.
You need xpad.ko for the controller to work and ff-memless.ko for the vibrators.
Unfortunately these have to be built for the kernel you are running and as far as I know nobody has built any for the nexus 5 yet
Sent from my Nexus 5 using xda app-developers app
Click to expand...
Click to collapse
Some other sources that might have some relevance:
https://jira.cyanogenmod.org/browse/CYAN-4469
http://www.androidsim.net/2011/07/how-to-30-connect-xbox360-wireless.html
http://forum.xda-developers.com/showthread.php?t=1568760
edit2:
This OPO kernel has xpad.ko included, I might check it out and see what happens.
http://forum.xda-developers.com/one...ernel-boeffla-kernel-1-0-2-0-beta-09-t2899974
Edit3:
Tried the kernel, switched on the xpad module, rebooted.... Still the same problem

Unable to use external DAC with S8+

I have no issue getting my Chord Mojo working with the UAPP app on my S8+ but when I try to use band camp, youtube or any other apps it will not route audio to the DAC properly. Note that UAPP uses a proprietary driver for routing data to the extetnal DAC. A notification comes up when connection Mojo to S8+ via micro usb-usb c otg cable(see screenshot below)
I have tried every option in the normal settinsg and developer mode but no matter what it just reverts back to "charge connected device". I have played around with all the USB settings in Developed mode;
Prevent automatic usb routing
Setting the usb device to audio source,
/MTP
Etc
Nothing works.
I even uninstalled UAPP, attached Mojo and opened band camp, still nothing. Worse yet, often it will freeze with Mojo connected and then restart itself or get stuck on the carrier boot screen during restart.
Seems that Android system is not allowing the device to connect properly although I can't be sure. I just want to be able to send all my audio to my exceptional Chord Mojo. Bummer because everything worked fine on S7 Edge running Android 7.0 when I selected MTP under developer options. Unless there's a fix I'll only be able to use Mojo with UAPP.

Im having very similar problem on S8, got an OPPO HA2 DAC, have bought a micro USB to USB C cable, and the phone is charging the DAC? It doesnt let me change the output as per your screen shot above.
Can anyone help?

I've ordered the meenova c to b otg cable, will report back.

i use andoird4viper with my DFR and it works. just had to lock the effect to headset and it should work system wide, as least for my case.

The meenova off cable made no difference with regard to getting Mojo to work with apps other than UAPP.

mstormer said:
i use andoird4viper with my DFR and it works. just had to lock the effect to headset and it should work system wide, as least for my case.
Click to expand...
Click to collapse
I'm not rooted and don't want to root.

Still no fix in sight but it is definitely a software issue and most likely with Android system processes.

Pixel3 not visible to PC (USB Transfer mode)

I am using my USB to USB-C Cable form my Nexus 5X, which works flawlessly with that one.
With the Pixel, however, I don't get it showing up in Transfer mode (as a drive).
When using PTP mode it becomes visible, but of course only showing picture folders.
Cable works 100% fine as far as I know, also with the Tool-All-In-One etc.
Any idea how enable USB-Transfers from PC to Pixel3?

fronten said:
I am using my USB to USB-C Cable form my Nexus 5X, which works flawlessly with that one.
With the Pixel, however, I don't get it showing up in Transfer mode (as a drive).
When using PTP mode it becomes visible, but of course only showing picture folders.
Cable works 100% fine as far as I know, also with the Tool-All-In-One etc.
Any idea how enable USB-Transfers from PC to Pixel3?
Click to expand...
Click to collapse
When the pixel3 is connected did you look in the settings to see what USB mode is selected? You might need to change the mode to File Transfer. Also you have to unlock the phone after connecting it before it shows up. I'm not near a computer so I can't give the exact details.
EDIT: When the phone is connected go to Settings/Connected Devices/USB. Then in the section "Use USB for" make sure File Transfer is selected.

Thank you for the reply.
There's a "Yes" to all of that: USB mode is "Transfer Files", set directly via Setting but also checked on unlocked screen.
PC explorer shows Pixel3 in PTP mode (images folders only), which vanishes completely when switching to file transfer mode.
With Pixel 3 we are able to change which device controls USB connection, - i can't change this for this connection, it stays in "This device" (P3), "other device" (does this mean PC?) fails and reverts to "this device".
Is this a setting relevant only for Phone-to-Phone connections?

My Pixel 3 is doing this now with Android Auto after I got the February update. I can't change USB mode and Android Auto only launches on my phone instead of my car head unit. If I try to manually change the the USB mode to anything other than charging it immediately resets like nothing happened. If I change the control type to "other device" it reverts to "this device" and grays out the option.
I have tried a few cables, two different cars, and enabling USB Debugging but nothing helps. I think Google did this and we might have to wait on a fix.

As a follow-up, I've seen some people with this issue fix it by getting a USB C cable that is 65 ohm, or getting a USB 3.1 SS+ cable. I have one on order and will update when I receive it.

zeropants said:
As a follow-up, I've seen some people with this issue fix it by getting a USB C cable that is 65 ohm, or getting a USB 3.1 SS+ cable. I have one on order and will update when I receive it.
Click to expand...
Click to collapse
Thank you!
So this is a confirmation that this indeed is a bug needing some fix?
I did a quick look around and couldn't really find such a cable - what would I search for specifically?
I did not get confidently lucky with 65 ohm, USB 3.1 or SS+ terms..
(Also, i am quite sour about Google not including an USBCtoA connector.)

fronten said:
Thank you!
So this is a confirmation that this indeed is a bug needing some fix?
I did a quick look around and couldn't really find such a cable - what would I search for specifically?
I did not get confidently lucky with 65 ohm, USB 3.1 or SS+ terms..
(Also, i am quite sour about Google not including an USBCtoA connector.)
Click to expand...
Click to collapse
From my view it's a bug, but I don't have much to confirm with, just personal experience. I'm going to re-check Apple Carplay too to make sure it's not a vehicle fault.

Another failure.
So far I've tried 4 cables, including a USB-C 3.1 cable. I've tried 2 different cars with Android Auto support. No combination has enabled AA on the cars head unit.
I plugged my Pixel 3 into a laptop work USB 3 support and it connected to file transfer.
As a follow up, my wife's iPhone XR connects to Car Play almost instantly.

I found out my issue is specifically with Android Auto, and I have since fixed it. I had to remove all system updates to Android Auto and let it update and setup from scratch.

I finally managed to get my Pixel 3 recognized for file transfer.
Device manager showed a problem with the Portable Device - MTP device (yellow attention sign). I tried to update that driver, failing, even with the one from google directly .
However, i got the hint that missing system update (Windows) might be the culprit.
So I checked, installed the 2 it showed, and .. .. Pixel 3 showed up in device and file manager.