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Re: Interrupts and Serial Ports
- From: Andrew Lunn <andrew at lunn dot ch>
- To: Steve Knowlton <sknowlton at custom-mfg-eng dot com>
- Cc: ecos-discuss at sources dot redhat dot com
- Date: Mon, 8 Nov 2004 15:16:01 +0100
- Subject: Re: [ECOS] Interrupts and Serial Ports
- References: <53e0555cc0fb5972fe3b7b33d4cd3088418ccf3e@Custom>
On Fri, Nov 05, 2004 at 08:33:07AM -0500, Steve Knowlton wrote:
> I have an EB40A board. I am trying to read an incoming data stream on
> Serial Port 1
> that arrives about every 15 sec. I can see the Rx LED on the port
> flashing every time
> a packet arrives.
>
> I am trying to read data coming into the port using cyg_io_read using a
> polling method.
>
> I was reading the documentation on the ecos serial driver and it claims
> that the
> incoming data is buffered until it is read. Is this true because it
> doesn't seem to work
> that way. I never seem to read anything from the port. I have tried both
> blocking
> and non blocking reads. Occassionally I get a -11 error which means that
> the data is
> not available and that the user should try again later. The returned
> length is always 0 so
> that seems to prove that I am not reading anything.
>
> This does not seem to be a very good method and I was wondering if there
> is an ecos interrrupt routine I can use that would execute whenever data
> arrives at the port.
> Presumably ecos assigns an interrupt vector for the port. If so, how can
> I use this?
eCos comes with two serial drivers. There is a very basic one as part
of the HAL. This is designed for diagnostic output and is
polled. There is also a full serial driver which is interrupt
driver. You should make use of this full serial driver and you should
then get better results.
Andrew
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