From: Jonathan Larmour <jlarmour@redhat.com>
To: harri.siirtola@vtt.fi
Cc: ecos-discuss@sources.redhat.com
Subject: Re: [ECOS] AT91 interrupt driven functionality
Date: Wed, 12 Sep 2001 11:05:00 -0000 [thread overview]
Message-ID: <3B9FA3E0.6B21E474@redhat.com> (raw)
In-Reply-To: <3.0.32.20010912110840.009b1730@vttmail.vtt.fi>
harri.siirtola@vtt.fi wrote:
>
> I wrote:
> >> 1. I can't find any references to the tx & rx buffer pointers & char
> >> counters (US_RPR, US_TPR, US_RCR, US_TCR), not even in the register address
> >> definitions in plf_io.h. Shouldn't there be some in order to use buffered
> >> I/O (or non-blocking transfers)?
>
> Jifl:
> >All we need to know is that data is ready, and we can just read the RHR to
> >get it, surely? I'm not particularly familiar with the AT91 driver, but the
> >driver code seems to make sense.
>
> Looking at the USART description, the Peripheral Data Controller takes care
> of buffered USART I/O. I think one should init the buffer pointer (US_TPR
> in tx case) and write data count to US_TCR. The transfer is triggered by
> TXRDY and ENDTX interrupt is asserted when the buffer is empty. Transfer is
> restarted by writing a non-zero value to US_TCR. There's still something
> unclear in the rx case, so please look at it when you have time.
I'm afraid time is not something we have in abundance. Can I suggest you
have a go at it yourself? You seem like you have a promising theory, so
perhaps just follow it up and see if it works!
> I don't use any net functionality, nor did I enable it in my config. I
> updated my CVS a month ago, are there some modifications to USART
> functionality or just networking?
It was just a suggestion as if you had had the net package enabled, it
might mean a particular bit of code may be responsible for the dropped
characters.
Jifl
--
Red Hat, Rustat House, Clifton Road, Cambridge, UK. Tel: +44 (1223) 271062
Maybe this world is another planet's Hell -Aldous Huxley || Opinions==mine
next prev parent reply other threads:[~2001-09-12 11:05 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-09-12 1:09 harri.siirtola
2001-09-12 11:05 ` Jonathan Larmour [this message]
-- strict thread matches above, loose matches on Subject: below --
2001-09-11 6:26 harri.siirtola
2001-09-11 18:02 ` Jonathan Larmour
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