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RE: AT91 ADC support


Hi Sergei,

I have attached an updated var_io.h that includes ADC support for the
AT91M55800A. I took the opportunity to define the number of channels per
ADC in this file. It can be overwritten per platform basis since
AT91SAM7L64 for instance has 4 channels only.

The definition of AT91_MAX_ADC_CHAN must be removed from
devs/adc/arm/at91/current/src/adc_at91.c. I have not joined any patch
for it since I will hopefully submit a new driver that support both
ADCs.

Christophe

-----Original Message-----
From: Sergei Gavrikov [mailto:sergei.gavrikov@gmail.com] 
Sent: 27. mai 2010 18:38
To: Christophe Coutand
Cc: John Dallaway; eCos Patches
Subject: RE: AT91 ADC support

On Thu, 27 May 2010, Christophe Coutand wrote:
> Hi John,
>
> It's pretty easy to add the required definition for the AT91M55800A
> targets. The only thing I see now is that this device contains 2 ADCs
> which I have not considered before. I guess there are several ways out
> of this:
>
> 1- Update the actual AT91 ADC driver to make full use of the
> AT91M55800A targets. I guess should be done by loading a second ADC
> instance (one for each ADC. I have not been through all the thinking
> here...).
>
> 2- or limit the AT91 driver to use only ADC0 of the AT91M55800A target
> for the time being.
>
> 3- or exclude AT91M55800A targets for the time being.
>
> IMO #1 is best but I cannot give any time frame for completing it.

Hi Christophe, John

I would prefer #1, if you want I can add that in AT91/ADC CDL/sources.
One thing: I won't be able to test it on real hardware (only build
process can be tested me).

John, what do you think: Can we add the second ADC instance without a
testing?

> One additional weakness of the driver is that it is made for up to 8
> channels. It is defined nowhere what the targeted CPU can actually
> handle, this is left to the user when configuring eCos. I believe this
> is pretty fine since the user must anyway know which signal he wants
to
> sample but you might disagree on that one.

I know only one target which would use all 8 channels :-) That's eCos
i386/Linux synthetic target.

Thanks for collaboration.

Sergei

> Regards,
> Christophe

Attachment: at91_M55800A_var_io
Description: at91_M55800A_var_io


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