# USB Host not working in CM7



## skunkfu (Sep 2, 2011)

Hey guys,

I've tried mounting a few flash drives to the TouchPad using at least two different OTG connectors but to no avail. I've looked in the /mnt/usbdisk directory but it's empty. There's no notification of connection (not sure if one pops up anyway) I've tried fat, fat32, and ntfs flash drives, restarted while connected, and even a keyboard. Nadda.

Does this current build of CM7 support USB Host atall? I had asked dalingrin a few weeks back and he said its supported, just like the Nook.

I've also updated to alpha 2.1 and noticed this change: * USB mounting in vold added

I must be missing something here!

Cheers


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## green (Sep 2, 2011)

We did not get self-powered usb host to work yes, so you need to also supply usb power somehow. Either with a hub that powers upstream port or by using a Y cable to supply power from somewhere


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## skunkfu (Sep 2, 2011)

Sorry green I should have mentioned that yeah I am using a Y cable with the power port connected to the PC.

cheers


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## green (Sep 2, 2011)

works for me, so it should be something on your end.

Try plugging your otg cable into touchpad all by itself, then plug back normal cable, adb in and do dmesg, see if EHCI Hub messages are there.
If not, that means your otg cable is not really otg as it does not short pin4 to pin5.


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## chefjw (Sep 15, 2011)

Works with everthing I have tried. Keyboard, hard drive, usb thumbdrive, usb card reader. I happen to use a gigawire usb mini hub from radio shack and a iphone usb backup purely for portability. Hub is model 26-424 ultra compact usb 2.0 hub its only like an inch square and thick as a number 2 pencil. Plug the red usb into backup battery, plug the black into the otg and off you go.


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## skunkfu (Sep 2, 2011)

I connected the OTG cable, disconnected, connected USB cable and ran adb. Not sure what I'm looking for here so I attached the results, but I think that might be the EHCI hub messages your talking about.

Good to know it works for a range of goodies! I just always have bad luck with things not working :erm (1):

cheers

View attachment 4620


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## green (Sep 2, 2011)

Yes, this otg cable is good. everything should be working.
Make sure external power actually makes its way to the device.
Try with a hub too?


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## skunkfu (Sep 2, 2011)

Good to know that works. I've got another Y cable coming my way and if that doesn't help, I'll fetch a hub. Needing one anyway.

I'll post when I eventually get it working.

Cheers for the help green, and for the work you've been doing so far


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## thehappysquirrel (Sep 27, 2011)

So what cables do I need exactly in order to hook up, say, a thumb drive? Do you have any recommendations for where to get a reliable one? Thanks


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## skunkfu (Sep 2, 2011)

squirrel, have a look at this thread here...

http://forums.precentral.net/hp-touchpad/296505-functional-usb-host-touchpad.html

Just ignore all the WebOS bits!


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## thehappysquirrel (Sep 27, 2011)

I get that a y cable is necessary for something like a portable hard drive (one of the bigger ones) but for a normal thumb drive is it necessary?


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## skunkfu (Sep 2, 2011)

Yeah as I see it any devices that are connected with USB needs power in order to function, that will include thumb drives and even keyboards.


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## chefjw (Sep 15, 2011)

Not only does the usb device require power but the otg cable needs upstream power to be recognized by your touchpad. Fat32 seems to be required on thumbdrives and hard drives in my experience. I have a frankenstein setup myself using a ipod emergency charger for power.


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## exponent (Aug 24, 2011)

chefjw said:


> Not only does the usb device require power but the otg cable needs upstream power to be recognized by your touchpad. Fat32 seems to be required on thumbdrives and hard drives in my experience. I have a frankenstein setup myself using a ipod emergency charger for power.


Yeah, I think I'm gonna make a mintyboost just to power the usb host. I'm just wondering... could you use an OTG cable, a Y-cable (to have external power, of course), and a usb hub to have multiple usb devices (such as keyboard, controller, flashdrives, etc)?


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## TchnclFl (Aug 22, 2011)

exponent said:


> Yeah, I think I'm gonna make a mintyboost just to power the usb host. I'm just wondering... could you use an OTG cable, a Y-cable (to have external power, of course), and a usb hub to have multiple usb devices (such as keyboard, controller, flashdrives, etc)?


Yup.


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## chefjw (Sep 15, 2011)

If you get a hub with powered upstream like the gigawire I posted earlier you do not even need the y cable. I need to make make a shorter cable for the hub so I do not have to wrap up the cable.


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## twosheds (Oct 2, 2011)

I've been testing my TP with an OTG cable and a powered hub ( didn't need a 'Y' cable) and have successfully attached everything I've tried but after using it last night I left it overnight (in Webos with the screen off in airplane mode) to charge using the HP supplied charger and cable. This morning the battery had only 17% charge and the battery indicator showed that it wasn't charging. After a reboot (back into Webos) it's charging again.

I'll have to remember to reboot before putting it on charge after using the OTG cable.

Has anyone else experienced this ?


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## ozzuneoj (Oct 14, 2011)

Just an idea... you may want to check which ends of the Y you are using. I'm not sure if it matters which you use but technically the two short ends should go into your Touchpad and your power source (usually a thinner wire), with the long end going to your USB device. This is how a USB-Y cable would normally work when connected to a computer that didn't supply enough power through a single USB port.

It may work another way, but this is how I've seen them work in the past. I have a 2.5" drive from 6-7 years ago that would only work when wired this way.


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