Re: [Gumstix-users] Re d LED GPIO21 blinking

[Ash C. <ash...@gm...>]

The LED may simply be triggered by the kernel on a heartbeat trigger
or similar.  Have a look in /sys/class/gpio/gpio21 and do a 'cat
trigger' to see if there is a trigger set up.
-Ash

On Fri, May 13, 2011 at 1:22 AM, Victhor <vic...@gm...> wrote:
> I found a way to make it stop blinking, but I suspect what I did wasn't
> the right procedure(it's a workaround, rather). The LED did stop
> blinking, but I can't use it for GPIO for some reason.
> devmem2 0x480025e8 w 0x11D0000
> should fix it. Actually, I found that what controls the behavior of this
> pin is the first 3 bits, there is likely documentation about this on
> http://wiki.gumstix.org/index.php?title=GPIO and
> http://www-s.ti.com/sc/techlit/spruf98 but I have no idea on how to use
> the information.
> If you don't add the last 4 bits, the LED will be always lit. Same if
> you set the first 3 bits to something else than 11D, but I didn't try
> looking much into it.
> The register will reset upon reboot, and so you will get the blinking
> LED again. The wiki article above explains how to make such changes
> permanent.
>> Any news? I am having the same issue. I don't remember having it before. I
>> haven't tested it fully, so I can not tell exact problems at this moment.
>> But GPIO21 blinking red doesn't feel good.
>>
>> -david
>>
>>
>> tcf011 wrote:
>> >
>> > I am booting my Overo water / summit board off a microSD card configured
>> > with Ubuntu 9.04. However, unlike when I boot into Angstrom (w/o the SD
>> > card), the red GPIO21 LED starts blinking when booting of the microSD
>> > card. I can log in, compile code and execute code, but communication over
>> > the extra UART ports does not appear to be working. As a side note, I am
>> > remap two GPIO pins on the 40 pin header to ttyS1 so I can communicate
>> > over it, this is done after I log into Ubuntu though. The console, ttyS2,
>> > appears to work fine. Does anyone know what would cause this LED to blink,
>> > and if it could be affecting my ability to communicate over serial?
>> >
>>
>
>
>
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