Otg + charging solution for btssm w/ vag-com?

I picked up a cheap android phone to use as a dedicated btssm screen and can't seem to find a direct solution to otg + charging using the vag-com cable. Btssm works fine directly connected to the vag-com with a usb c adapter. I've tried a usb hub and that powers the vag-com but doesn't charge the phone and I've also tried a Y type adapter but that either charges the phone or connects to the vag com depending upon order of plugging in, but not both. Has anyone come up with a solution for this? Ive been reading through the nexus 7 thread but I don't think that the timur rom applies to the newer os (10)

Are you sure that your phone supports otg at all?

Yes, confirmed before I bought it. Seems like it’s a common issue that otg data transfer and charging don’t work at the same time. There’s a fix I found with a resistor soldered on a the back of a micro usb (pin 4 to pin 5) but this phone is usb-c. Samsung Galaxy A01.

Maybe ask the question on the BtSsm official thread. You may get more feedback. I can't answer your question cause I am still using the good ol N7 with Timur on it.

Maybe ask the question on the BtSsm official thread. You may get more feedback. I can't answer your question cause I am still using the good ol N7 with Timur on it.

 

 

Done. Thank you!

Does it work if the phone can do wireless charging?

Does it work if the phone can do wireless charging?

 

 

What a great point. I hadn’t considered this. After some quick research I find the phone doesn’t support wireless charging though.

I am using an old Galaxy S7 which does support wireless charging - I couldn't say whether it will work with the VAG-Com cable though...

 

- I am using it in my 2021 Crosstrek to run Android Auto via Hot spot from my main phone... probably to no benefit and a bit of unnecessary hassle - but I wanted to see if it would work LOL

 

AND don't really use phone much for phone stuff when driving - just wanted maps working without paying a premium for OEM Sat NAT system!

I answered in the BtSsm thread, but this is a better place for it:

 

OTG + Charge totally depends on the device. On the Nexus7 2013, you need a hacked kernel (Timur's ROM has that hack, and I ported it over to ElementalX at one point in time). I use a Galaxy Tab S2 8" currently for in-dash tablet purposes, and that just requires a 121 kOhm resistor from the ID pin to GND to enable OTG + fast-charge (I run LineageOS 16, so Android 9).

 

If you don't know how to do any of the above, then your best bet is to ask over at xda-developers forums.

 

If your device is a Samsung device, it may likely also work with the 121 kOhm resistor trick (or maybe another value). Here's my post on the xda-developers forms showing where I found the resistor value for OTG + charge for the the Tab S2 8.0 (built-in support from the factory, likely similar for other Samsung devices): https://forum.xda-developers.com/showpost.php?p=83675315&postcount=15

Edited October 26, 2020 by solidxsnake

Thanks solidxsnake. Did some research and parts are on the way to try the resistor mod. Most info I could find was for micro usb but looks like it translates to usb-c as well. Will report back with my findings.

Hey mate did you happen to get your setup to work?

 

I have a nexus 7 (2nd gen) and a tactrix 2.0, it is driving me insane... It worked for a little while, now it just sucks.. BTSSM and timur's rom worked great at the start, it would connect properly, shut down when the car turned off etc. BUT it would discharge about like 5% per hour if i left the tactrix usb cable plugged in. Without the tactrix it would be <1% per hour no worries.

 

Now days, it wont charge or recognise that there's plenty of power avaiable to charge whilst being connected to the tactrix. Half the time it wont open btssm properly or go to sleep when the car turns off.

I've tried the 120k resistor trick, made my own OTG cable with thicker wire (could get over 1000mah charge rate), tried a 4 port USB hub (though it was a very cheap unit). NOTHING seems to work anymore.

 

I hope you have had better luck than me!

I think your total setup is wrong from beginning.

If tactrix is draining power in pad sleep mode - you had to connect it via a relay circuit to shut it up on ACC power loss. Or via ACC powered hub.

If your pad stopped working fine - first i would try to connect normal charger and monitor the app behavior. If it works same - reset the pad and try again. If it works in same manner - your pad is faulty.

 

When i had Nexus in my car - I paid for custom intelligent power supply unit, which was integrated to my pad (and battery removed) along with USB hub via otg.

the PSU had following features:

- simulated nexus battery, so I never had battery "discharge" issues

- it has idle mode (it had 8 hour sleep counter - so if I use my car within 8 hours after last ride - it wakes up from sleep).

- it went to power off mode after 8 hour idle time and powered up when car started.

- it has a self made otg solid wire between devices (to avoid bad contacts or any other problems of cheap China otg wires).

- it has integrated 4 port USB hub, powered via otg.

- it has 15 seconds sleep delay (to avoid sleeping/waking up during car restart)

- and it has a separate charge cable for my mifi router which i used for internet.

Additionally i made an external plate for power and volume buttons which i integrated in the convenient place.

Well strangely enough, it started working pretty well!

 

I think the biggest thing people don't realise is the order in which you plug you OTG in. Must be plugged into the power supply first, then slave, then N7 right?

 

I also bought an "ORICO 4 Port USB3.0 Desktop HUB" which has an extra micro usb port for power supply. My OTG cable was not a Y type cable (but it also seemed to work reliably compared to the cheap Y cables I tried, so I bought a "USB 3.0 Cable Dual Power Charge Cables Y Adapter Male to Female Cord" off ebay.

 

These cables and my existing power supply give up to 8-900mA charge rate so far PLUS my discharge problems look to have disappeared. This morning showed 63hrs off time for11% loss. 0.17% per hour seems pretty good.

 

Now I just have to make BTSSM more reliable. I drove to the fuel station, turned the car back on and got a "usb virtual something something" error..

BtSsm has been very reliable for me since 2016. When it is not, it is usually due to an issue with poor (USB or OBD II) connections.

Since you're using Timur's ROM, you made sure there is no app waking up the tablet right? I think it is called RTC alarms, making sure everything is unchecked. Usually, as soon as you install or update an app, something will get checked there again.

 

 

Having said all of that, the long term issue that I have never resolved is the ROM being unable to remount all USB devices after several on and off cycles of waking up the tablet. Only remedy so far is reboot. It sucks but oh well.

And now it stopped working... This is the bit that frustrates the hell out of me! It was working great, next minute it give is the "error reading from usb/otg: attempt to invoke virtual etc etc".

 

Now I can't get it to reconnect at all, says its charging though nothing is plugged in, the list goes on.

 

I have another OTG cable on its way from amazon, maybe that might help. Otherwise I think I need to remove the tactrix and try something else?

 

FYI my nexus is running 6.0.1 android which I believe is the marshmellow version which potentially gives issues?

 

EDIT: I just saw on the BTSSM thread that the port in the hub which you plug the tactrix into can affect things, it might need to be in the last position or something. I have downloaded and OTG app the check things later on.

 

Edit 2: New cable just arrived, still the same issue. I also read that the use port on the tactrix can fail, time to try a new OBD reader!

Edited February 25, 2021 by crjohnson

fwiw, I don't use a tactrix cable. I've been using a cheap vag com cable.

Yea I think I need to try that next. I actually had it working last night without the hub plugged in. BUT it would discharge like >1.5% per hour. Got home and switched the car off etc.

Plugged in the hub this morning, now it says USB not connected. Tried multiple times to plug it in in the correct order etc, nothing still... Might be worth going to an android head unit of some sort soon.

I also recall that I had to invest in a higher quality USB hub. I first used a cheap one and I kept having problems. After 'upgrading' the USB hub (and having it powered as well), it's been pretty stable.

Hey guys small update. After a number of issues where I had to restart the nexus, something made me think about the power turning on-off-on when starting the engine and if this screwed up the nexus.

I changed the power supply from the 12v accessory plug in the console to the "headlight washer" which is on during starting and normal running, off when the key is on the first click.

 

So far this is working great, no issues, fingers crossed it keeps going!

 

You'll have to check which fuse this is on your cars or check with a voltmeter. Goodluck!

Forgot to mention that I have a Time Delay Relay device for that (similar to this one). Essentially, when the key goes from the on to off position (or when I crank the engine), the timer begins the countdown and keeps power to the device for ~15 seconds. Without it, I was getting similar issues where the USB devices try to unmount since power is getting lost, and then remount when power comes back. Big mess..

I have one I need to install. I solved it with a simple switch that I just don’t turn on until the car is running.

Yeah. As a matter of fact, I installed two of these in the car: one for the cranking issue, and one for the back up camera. This way, when I back up, the camera turns on, then when I disengage the rear gear, the camera stays on for an additional 10-15 sec as well. Quite helpful in some backing up situations.

 

Unrelated to the Nexus, but also installed a 3rd brake light flasher a few years back (from the same manufacturer) for the tailgating folks.. This one has a nice feature where it flashes the first time you hit the brakes, but then will not flash if you hit the brakes again within 10 secs of the first time you did. This time frame is customizable as well as the flashing rate.

Another option is just two diodes. Pull 12v from both the ACC and hot when running, put a diode on each line, then tie the output of the two diodes together and use that for your 12v. Just make sure the diodes are rated higher the the amperage you'll be pulling. Works well for me.

On 10/25/2020 at 7:23 PM, solidxsnake said:

I answered in the BtSsm thread, but this is a better place for it:

 

Not sure, but I think the BTSSM thread was deleted...

SC

Yes it was after the server update