[En-Nut-Discussion] Receiving weird 0 on UART

[Manuel Mausz]

Hi,

we've tested a little bit more and we're receiving the "0" even if no client is connected. So the "0" must be from the "transmission
direction turnaround". The question is why do we get this? - And how can we avoid this?

/ manuel

> -----Original Message-----
> From: en-nut-discussion-bounces at egnite.de
> [mailto:en-nut-discussion-bounces at egnite.de]On Behalf Of Ernst Stippl
> Sent: Tuesday, April 18, 2006 11:14 PM
> To: 'Ethernut User Chat (English)'
> Subject: AW: [En-Nut-Discussion] Receiving weird 0 on UART
>
>
> Hi Manuel!
>
> Maybe the weird "0" you are receiving is created by the "turnaround" of the
> transmission direction on the RS485 link? Are you receiving the "0" for
> every character sent? How is the echo done on the client side? Is each
> character echoed immediately when received by the client or is the text
> received and stored upto a cr/lf and the sent back by the client?
>
> regards
> ernst
>
> -----Ursprüngliche Nachricht-----
> Von: en-nut-discussion-bounces at egnite.de
> [mailto:en-nut-discussion-bounces at egnite.de] Im Auftrag von Manuel Mausz
> Gesendet: Dienstag, 18. April 2006 17:56
> An: Ethernut User Chat (English)
> Betreff: RE: [En-Nut-Discussion] Receiving weird 0 on UART
>
> I've just noticed that the list has deleted my attachment.
>
> Test prog @ http://www.netcore.at/misc/test.c
>
> / manuel
>
> > -----Original Message-----
> > From: en-nut-discussion-bounces at egnite.de
> > [mailto:en-nut-discussion-bounces at egnite.de]On Behalf Of Manuel Mausz
> > Sent: Monday, April 17, 2006 5:56 PM
> > To: en-nut-discussion at egnite.de
> > Subject: [En-Nut-Discussion] Receiving weird 0 on UART
> >
> >
> > Hi list,
> >
> > we're currently building a client<->server application and therefor
> > we're using the ethernut 1.3 rev. F board (as server). To communicate with
> the other selfmade boards(/clients), we're using a SN75176BP to convert from
> RS232 to RS485.
> >
> > For testing purpose our client board is just echoing all characters.
> > If we run the attached test program without the RS485 driver,
> > everything works as expected. But if we add the driver and ethernut is
> sending characters first (line 114), we always receive a 0 before we get the
> sent characters. If we run another test program which only let the client
> board send data, we don't get any 0s.
> >
> > Since we're stuck now, any input would be appreciated.
> >
> > Setup:
> > Driver SN75176BP:
> > PIND5 -> ^RE/DE
> > PIND2(RX) -> R
> > PIND3(TX) -> D
> >
> > Ethernut 4.1.3
> > UART1_HDX_BIT = 5
> > UART1_HDX_AVRPORT = AVRPORTD
> >
> > Regards,
> > / manuel
> >
>
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