Using OTG port on iMX25 PDK as Host Mass Storage

[geraldvahe]

Hello,

Recently, I was alerted to a customer having issues getting the USB OTG port functioning as a host on the iMX25 PDK with the 09_12 Linux drop.  So, I decided to try it.

It turns out that the loading of the modules have to be done in a particular order, or it will not work.

To get mass storage working to detect a USB Thumb Drive:  (Again, you MUST follow this order)

1) modprobe fsl_otg_arc

2) modprobe ehci-hcd

Of course, these modules must be selected in the USB features. 

Hope this helps.

[geraldvahe]

All,

Want to give you a bit of an update......My experimentation above was with a preliminary iMX25 PDK.  It had a USB MINI connector on it for the OTG connector.  For the production boards, they are now MICRO connectors.  One of my customers was still having problems, so I ordered this device:  (Same as my customer)

http://www.amazon.com/USB-Micro-Female-Male-Adaptor/dp/B0023FTRUO

It just so happens that PIN 4, which is the ID DETECT, isnt grounded.  This is necessary for the OTG port to detect that a HOST is connected!!!!!

So, if you are having trouble using the OTG port with my above description, add these steps (Or get a MICRO connector with Pin 4 grounded, like my MINI to USB A had!)

1) Follow my above instructions, only dont have the device connected when you MODPROBE the drivers.  If your using the 09_12 Linux release, you will see "USB HOST SUSPENDED"  This is because there is no device connected!

2) Plug in your device.  Nothing will happen, because the ID PIN isnt grounded.

3) Take a small PIN (Sewing pin etc), and short pin 4 of the connector u10 to the CASE of the MICRO connector, and hold it there.

WALA!!!!!  Your usb device will mount.

Hope this helps.