HDD on OTG port on XM

If I connect an external USB HDD to the OTG port on the XM, using a
mini-A to mini-B cable with pin 4 on the A plug grounded, providing 5V
power to the HDD from either the LCD connector P11 (pins 1/2 to 19/20)
or the camera socket P10 (pins 4/14/20/22/28/33/34 to 24/25/26)
because the OTG port will not provide sufficient power, should it work
correctly please?

Should I use P10 in preference to P11 or vice versa or does it not
matter?

If I connect an external USB HDD to the OTG port on the XM, using a
mini-A to mini-B cable with pin 4 on the A plug grounded, providing 5V
power to the HDD from either the LCD connector P11 (pins 1/2 to 19/20)
or the camera socket P10 (pins 4/14/20/22/28/33/34 to 24/25/26)
because the OTG port will not provide sufficient power, should it work
correctly please?

No.

Should I use P10 in preference to P11 or vice versa or does it not
matter?

The headers aren't going to provide more power than the OTG port.
What you need to do is insert a powered USB hub.

Plan B is to cut the LV side of the power supply and connect two power
plugs - one for the XM power plug and one for the HDD power plug. But
surely there must be somewhere on the PCB that I could just plug into
- the power is all coming from the same supply after all?

You may be able to do this, but there is no place that you can just plug in a cable. there is no connecotr for this. I would read up on it in the System Reference Manualand review the schematic. Either way you will have a cable coming in from the main supply and a cable going out to the auxilliary power conenctor on the USB HDD, even if it comes from somewhere on the board.

Now, you could use the USB Host port and use two USB cables from there to connect to the USB HDD.

Gerald

Many thanks - all working. I simply put a power socket on the case and
connected two power plugs to it inside the case, one for the BB and
one for the HDD. I then connected a mini A to mini B usb cable between
the OTG port and the drive [all inside the case] and it all worked. It
is formatted under RISC OS and appears as SCSI::4.$ (156Gbyte) rather
than under Linux or Windows (and so is not seen by the Linux GUI) but
that is a bit beside the point.

Glad to hear you got it going! Any chance you can share some pictures?

Gerald

Picture here:

http://www.svrsig.org/BBXM.jpg

Case design and parts list:

http://www.svrsig.org/BeagleXM.pdf

Oh and boot.scr added to demo SD card available here
http://www.svrsig.org/software/BootSc.zip (RISC OS ROM image may be
added, 4Mbytes, from RISC OS Open web site).

Some more pictures, this time with RISC OS running:

http://www.svrsig.org/BB1.jpg
http://www.svrsig.org/BB2.jpg

Some more pictures, this time with RISC OS running:

http://www.svrsig.org/BB1.jpg
http://www.svrsig.org/BB2.jpg

I'm looking forward to a blog post I can put in the BeagleBoard.org RSS feed.