Thanks to a recent video by reverendkjr on Youtube, we now have a confirmed USB OTG method for CM9.
http://www.youtube.com/watch?v=Nc7tlPwFQpg
This has lots of potential and since I did not see much talk about it here, I decided to create a thread with what you need to buy listed in reverendkjr's video and what works. I would recommend only buying from Amazon Fulfilled sellers as they are backed by Amazon's return policy. All 3 items only cost a little over $10.
OTG Cable:
http://www.amazon.com/gp/product/B005QX7KYU
USB Y Cable:
http://www.amazon.com/gp/product/B0041CFFBM
2AA Battery Powered Portable USB Power Supply:
http://www.amazon.com/gp/product/B003M9Z5F6
(Added September 7th)
OTG Cable With Female MicroUSB (Allows you to use any microUSB charger as the power supply)
http://www.ebay.com/itm/130740524313?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649
OTG Cable With Male Full Size USB (Allows you to use any power supply with regular USB port)
http://www.ebay.com/itm/Micro-USB-H...i9100-S3-i9300-i9220-i9250-XOOM-/140825132367
You can use whatever source of USB power you want including a wall charger, but I bought the 2AA battery powered supply above and can confirm it works.
Compatibility List:
-Multiple USB devices will work if you use a USB hub. A non-powered one works fine for me since you will already have a separate power source.
-USB keyboards and mice work fine including all basic functions like scroll wheel on the mouse, num and caps lock on the keyboard.
-FAT32 formatted flash drives will mount by default under "/mnt/usbdisk".
(Added September 7th)
-If you want to mount NTFS drives or multiple flash drives, download Drive Mount. This software will mount drives under "/mnt/sda1", "/mnt/sdb1", etc. I can confirm it works for multiple drives and NTFS/FAT32. It was removed from Google Play so the apk has been posted. If anybody has had success with other NTFS mounting software please post your results.
(Added April 6th)
-I tried a Rosewill USB SATA/IDE externally powered hard drive reader and was able to mount a 400GB SATA 3.5" HDD using Drive Mount. Just to see what would happen I tried a SATA DVD drive but Android doesn't recognize it and probably doesn't even support the CD/DVD file system.
(Added April 7th)
-USB card readers will work, but I've had mixed results.
USB Device Info:
If you want to diagnose items and see some info about what the Touchpad is detecting, download USB Device Info free from Google Play. Everything shows up under the Linux tab. This shows some useful info about devices including current draw, device identification, etc. I tested it with a USB hub and a few flash drives and it successfully showed entries for the hub and the flash drives. It wont tell you if Android has drivers for the device, but merely IDs the device(s) confirming the connection if working.
(Added Dec 9th)
A plugged in USB OTG adapter will show up as "Qualcomm On-Chip EHCI Host Controller" under the Linux tab regardless of whether or not power is present. This is a good way to see if you have a working OTG adapter.
Flash Drive Unmounting Issues:
Flash drives are called an SD Card when mounted. There is no option to unmount a flash drive unless you use Drive Mount, so if you notice SD card removal error messages they are referring to your flash drive and not the Touchpad's internal memory partition that is mounted as /sdcard.
When a flash drive is removed or powered off without being unmounted, its common to get a "android.process.media" force close, just tap OK.
Charging:
You will not be able to charge via micro USB while using OTG even if your power source has enough current. You can charge via the Touchstone just fine. Knowing this, you can set up a really nice docking station by using the Touchstone as a stand/charger and then using the microUSB slot for peripherals like a USB keyboard and mouse connected to a hub with spare ports for flash drives, etc.
(Added September 7th)
Insufficient Available Bus Power Fix:
If you get this error, I haven't yet, some users have had success using this app posted on Rootzwiki.
http://www.youtube.com/watch?v=Nc7tlPwFQpg
This has lots of potential and since I did not see much talk about it here, I decided to create a thread with what you need to buy listed in reverendkjr's video and what works. I would recommend only buying from Amazon Fulfilled sellers as they are backed by Amazon's return policy. All 3 items only cost a little over $10.
OTG Cable:
http://www.amazon.com/gp/product/B005QX7KYU
USB Y Cable:
http://www.amazon.com/gp/product/B0041CFFBM
2AA Battery Powered Portable USB Power Supply:
http://www.amazon.com/gp/product/B003M9Z5F6
(Added September 7th)
OTG Cable With Female MicroUSB (Allows you to use any microUSB charger as the power supply)
http://www.ebay.com/itm/130740524313?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649
OTG Cable With Male Full Size USB (Allows you to use any power supply with regular USB port)
http://www.ebay.com/itm/Micro-USB-H...i9100-S3-i9300-i9220-i9250-XOOM-/140825132367
You can use whatever source of USB power you want including a wall charger, but I bought the 2AA battery powered supply above and can confirm it works.
Compatibility List:
-Multiple USB devices will work if you use a USB hub. A non-powered one works fine for me since you will already have a separate power source.
-USB keyboards and mice work fine including all basic functions like scroll wheel on the mouse, num and caps lock on the keyboard.
-FAT32 formatted flash drives will mount by default under "/mnt/usbdisk".
(Added September 7th)
-If you want to mount NTFS drives or multiple flash drives, download Drive Mount. This software will mount drives under "/mnt/sda1", "/mnt/sdb1", etc. I can confirm it works for multiple drives and NTFS/FAT32. It was removed from Google Play so the apk has been posted. If anybody has had success with other NTFS mounting software please post your results.
(Added April 6th)
-I tried a Rosewill USB SATA/IDE externally powered hard drive reader and was able to mount a 400GB SATA 3.5" HDD using Drive Mount. Just to see what would happen I tried a SATA DVD drive but Android doesn't recognize it and probably doesn't even support the CD/DVD file system.
(Added April 7th)
-USB card readers will work, but I've had mixed results.
USB Device Info:
If you want to diagnose items and see some info about what the Touchpad is detecting, download USB Device Info free from Google Play. Everything shows up under the Linux tab. This shows some useful info about devices including current draw, device identification, etc. I tested it with a USB hub and a few flash drives and it successfully showed entries for the hub and the flash drives. It wont tell you if Android has drivers for the device, but merely IDs the device(s) confirming the connection if working.
(Added Dec 9th)
A plugged in USB OTG adapter will show up as "Qualcomm On-Chip EHCI Host Controller" under the Linux tab regardless of whether or not power is present. This is a good way to see if you have a working OTG adapter.
Flash Drive Unmounting Issues:
Flash drives are called an SD Card when mounted. There is no option to unmount a flash drive unless you use Drive Mount, so if you notice SD card removal error messages they are referring to your flash drive and not the Touchpad's internal memory partition that is mounted as /sdcard.
When a flash drive is removed or powered off without being unmounted, its common to get a "android.process.media" force close, just tap OK.
Charging:
You will not be able to charge via micro USB while using OTG even if your power source has enough current. You can charge via the Touchstone just fine. Knowing this, you can set up a really nice docking station by using the Touchstone as a stand/charger and then using the microUSB slot for peripherals like a USB keyboard and mouse connected to a hub with spare ports for flash drives, etc.
(Added September 7th)
Insufficient Available Bus Power Fix:
If you get this error, I haven't yet, some users have had success using this app posted on Rootzwiki.
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