[ECOS] Ethernet traffic causing loss of bytes on UART

Gary Thomas gary@mlbassoc.com
Tue Sep 1 15:24:00 GMT 2009

On 09/01/2009 08:36 AM, Alex Lindeijer wrote:
> Hi All
> This problem is fixed. The drivers that came with our Python MPC8541
> eval board, acknowledged the ethernet interrput in the DSR (after
> processing!) and not in the ISR.
> It seems to work fine now.

How does that have anything to do with losing bytes on the UART?

BTW, IMO it's not safe/proper to acknowledge the interrupt in the ISR.
The ISR masks the interrupt and only after the network stack has fully
processed the data is it acknowledged and unmasked.  Acking the interrupt
in the ISR could lead to missing some interrupts.

> -----Original Message-----
> From: ecos-discuss-owner@ecos.sourceware.org
> [mailto:ecos-discuss-owner@ecos.sourceware.org] On Behalf Of Alex
> Lindeijer
> Sent: 1. september 2009 08:24
> To: ecos-discuss@sourceware.org
> Subject: [ECOS] Ethernet traffic causing loss of bytes on UART
> Hi
> We are running a serial port on 38400 baud and are seeing loss of Rx
> bytes. When unplugging the ethernet cable we have no problems.
> We are using a MPC8541, it has a PC16550D programming model for the
> UART. I see that the driver uses the FIFO and reads until the FIFO is
> empty.
> The Ethernet driver is a tsec driver .
> We encountered similar problems when writing to flash. We got some
> verification/write errors with Ethernet traffic going. In that case we
> masked the interrupts while writing to flash. But we don't want to do
> that when receiving bytes on the serial port of course.
> Has anybody else encounter such problems? Any hints in were to look? We
> have been looking into this now for some time and are getting a bit
> desperate.....;-(
> Cheers
> Alex Lindeijer

Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world

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