[Gta04-owner] GTA04A3 System Manual

Dr. H. Nikolaus Schaller hns at goldelico.com
Wed Oct 12 10:08:16 CEST 2011


Am 12.10.2011 um 09:57 schrieb NeilBrown:

> On Wed, 12 Oct 2011 09:22:23 +0200 Christoph Mair <christoph.mair at gmail.com>
> wrote:
> 
>> On Tue, Oct 11, 2011 at 11:41 PM, NeilBrown <neilb at suse.de> wrote:
> 
> 
>>> And the interrupt line from the accelerometer(s) are connected to GPIO lines
>>> on the CPU rather than on the power controller, which seems to suggest that
>>> the accelerometer cannot wake the system from sleep mode.  Is that correct?
>> I'm not sure about this but I think the processor can tell the power
>> controller that it wants to wake up.
>> 
> 
> Thanks.  I managed to find
>  http://processors.wiki.ti.com/index.php/AM/DM37x_Overview#General_Purpose_I.2FO_.28GPIO.29_Interface
> 
> which says
> 
> --------
> These pins can be configured for the following applications:
> 
> .....
>    Wake-up request generation in idle mode upon the detection of external events. 
> -----------
> 
> Which certainly supports your theory.

Yes, that is the way it is done on the OMAP system. The CPU isn't completely
powered down. But I am not sure how well this is implemented in the drivers.

> 
> There is certainly lots of documentation around for some of this stuff.
> Making sense of it when you are a hardware-newbie can be a challenge though.
> 
> Another correction:
> The feature comparison says:
> 
>     Feature    GTA02 / GTA01             GTA04
> 
>     RAM        256 MB (GTA01: 128 MB)    512 MB
> 
> And I thought "what, only twice the RAM", but I just checked my GTA02 and it
> says:
> 
>     Memory: 128MB = 128MB total
> 
> So either I was short-changed, or the comparison is wrong.

We over-estimated the GTA01 and GTA02 by factor 10 (in binary system)...

But there is a missing piece in the board initialization so that the GTA04
currently sees only 256 of the 512 MB that are installed [1].

Nikolaus

[1]: http://projects.goldelico.com/p/gta04-uboot/issues/261/



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