Originally Posted by Karmarock
What an incredible news!
There are quite a bunch of posts around about Razr USB host capability, but up to now (to my google capabilities) no one succeeded in connecting any external I/O!
I'm pretty sure about the wirings (at least according to pure guessing from your schematics) as I checked all of them with a tester.
The wiring I made is quite simple
on the micro USB side:
contacts 4 and 5 bridged
Data wires connected to its corresponding ones on the female USB.
Power and ground on the female USB taken from an male USB connected to a charger.
Now it comes the detail requests:
1) What does it happen when you connect your cable to the Razr. Does it recognize it in some way giving any notice?
2) Rooted is needed? (Mine is not yet rooted).
3) Any special setup/tweaking to have OTG working?
4) Where do you access the external I/O contenct? From a directory in \SDcard otherways where else? Can you name it?
5) What I/O have you succesfully connected? Any kind of memory stick works? Any kind of HD? Mouse? Keyboards?
Thanks in advance in the name of all of the Razr's users interested in usb host functionality!
The first try was with the Motorola LapDock, the second one with a custom USBOTG cable.
When you connect the RAZR to the USBOTG cable or to a LapDock, it says that a dock has been connected to the device (HD Multimedia Station or LapDock, both are recognized as docks, obviously).
So you have to connect something to your RAZR and it will be instantly recognized but the USB Device Connected notification is shown only in WebTop, not in Android.
The USBOTG cable HAS TO give power to the RAZR and to the devices you're connecting to it, otherwise the RAZR won't recognize the Dock Connected status.
Be sure your AC power is 5V with at least 1A, otherwise there won't be enough amperage for RAZR and the connected device and since the RAZR has got the priority, you'll only charge the device's battery and your connected USB device won't have the necessary power for working correctly.
ROOT is not needed for OTG USBHost operation as the device has been configured by Moto to work in USBHost Mode.
When you connect an external pendrive, the device will automatically create a device node and will automatically mount the connected pendrive/USBHDD in a directory created in /mnt.
I've successfully connected all the device I was able to use on ATRIX, including keyboards, mouses, an 8GB PenDrive and a 500GB external HDD.
I'm also about to see if I can do a modification to the ATRIX LapDock for including into it another USB HUB and a switchable (ON/OFF) 2.5 250GB SATA->USB HDD. If I'll success in this, I'll also post on xda-developers a thread with the instructions on how to do that.