Fwd: [gta02] u-boot boot menu regression ?

Wolfgang Spraul wolfgang at openmoko.com
Wed Apr 16 16:48:11 CEST 2008

Begin forwarded message:

> From: Werner Almesberger <werner at openmoko.org>
> Date: April 16, 2008 7:36:22 PM GMT+08:00
> To: gta02 <gta02 at lists.internal.openmoko.org>
> Subject: [gta02] u-boot boot menu regression ?
> Miles keeps on telling me about troubles with the factory and the boot
> menu, but I can't quite figure out what's going on. Can anyone please
> help ?
> The problems seem to be related to the latest change where I reduced
> the time u-boot spends sampling the buttons by one second. Now, while
> this could theoretically create a very small window in which AUX has
> to be pressed, all the delays u-boot incurs before even getting to
> that loop should leave more than enough time.
> Let me repeat the procedure for invoking the boot menu:
> - Press and hold POWER
> - give u-boot a few milliseconds (let's be generous and make this  
> 100ms)
>  to load itself and move out of harm's way
> - Press and hold AUX
> - Continue holding POWER and AUX until the boot menu comes up
> - Release POWER and AUX in any order
> The red LED (underneath AUX) can be used as an indicator for the
> deadline to press AUX. The LED flashes briefly when the device is
> turned on.
> If AUX is pressed and held by the time the LED flashes, u-boot will
> enter the boot menu. If AUX is not pressed and held until more than
> one second after the LED flashes, u-boot will not enter the boot menu.
> If AUX is pressed at time 0s < t < 1s after the LED flashes, the boot
> menu will be entered with probability (1s-t)*100%.
> So to make sure to enter the boot menu, just press AUX before the
> LED flashes. There should be about 1-2 seconds between pressing
> POWER and the LED flashing, so it should be very easy to get this
> right.
> Here's a timing diagram:
> http://svn.openmoko.org/developers/werner/bm.pdf
> If there is still a problem, I need to know what exactly is going
> wrong. Have you encountered a case where the timing is vastly
> different ? Is there something at the factory that prevents the
> use of the correct timing ? Does u-boot fail to bring up the menu
> despite following the correct timing ?
> Thanks !
> Cheers, Werner
> _______________________________________________
> gta02 mailing list
> gta02 at lists.internal.openmoko.org
> https://lists.internal.openmoko.org/mailman/listinfo/gta02

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