Problems with external 5V supply

[Jacques Bride]

hello all

I tried to apply the simple software patch on my 12.02  ubuntu
SnowBall system (on emmc) but seems that I cannot create the extvbus
file and set it to 0, even though I am root. Looks like the directory
is locked

when I type the command:

echo 1 > /sys/devices/platform/musb-ux500.0/musb-hdrc/extvbus

I get answer: "extvbus : no such file or directory"

I tried creating the file in the repertory but always same answer....

Any clue?
Thanks


2012/4/4 Patrik Klinger <patrik.klinger at stericsson.com>
>
> Hi,
>
> A wiki page has been created for the USB Host issue experienced on the Snowball A9500. http://www.igloocommunity.org/support/Work-around_for_USB-Host_issue
>
>
> Patrik Klinger
> Snowball Program Manager
>
> ST-Ericsson
> Office: +46 46 104525
> Mobile: +46 768 433547
> Email: patrik.klinger at stericsson.com
>
>
> On 2012-04-04 05:51, Håkan Berg wrote:
>
> Patrik: I have tried only USB2 devices. Mouse and keyboard direct and also via dongle. I have also used an 8 GB memory-stick, and it worked fine as well. So high-speed USB works, but I have not tried Ultra-Speed.
>
> Jacques: Regarding OTG power detection, I suppose you are rigth. I probably means that the detection somehow fails.
>
> Since I heard something about wardware error causing the USB problems I asked a guy at ST-Ericsson and got an explanation. The ground wiring for the power and USB parts was not done properly on the Snowball, causing ground level noise. This could have a huge impact when connecting and disconnecting a cable at the OTG port if current goes in either direction of the +5V lead, since that also means the same current goes through the ground lead.
>
> /Håkan
>
> Den 2 april 2012 17:00 skrev Richard Curnow <richard.curnow at stericsson.com>:
>>
>> Hi Kalle,
>>
>>
>> On 04/02/2012 03:47 PM, Kalle Vahlman wrote:
>>>
>>>
>>> But yes, there's a funny discrepancy on behavior with OTG power and
>>> "wall power" wrt bootup, mainly due to flashing I guess.
>>
>>
>> OK, that makes sense.
>>
>>
>>>
>>> Another way to reset the board is to press the blue button for 10s
>>> (yes, that long) to shut it down and then press it again to boot up.
>>
>>
>> That works for me.  Apart from the delay, I think it's preferable, because the switch feels a lot more resilient than the other one.
>>
>> Richard
>>
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>
>