AW: [ntp:questions] Re: AW: Re: AW: convert_rawdcf: parity check FAILED on my embedded Linux system

Torsten Krieger Torsten.Krieger at krieger-mis.de
Wed Oct 18 19:56:38 UTC 2006


Hi folks,

many thanks to all specially to Uwe his explanation help me a lot. It is now
working fine, the fault was that my embedded system FOX Board has not
scanned the RAW DFC receiver with 50 baud. The driver has set to the default
of 9600 baud when I tried to set it to 50 baud, but feeds back to the stty
call 50 baud. Mad World!!!

Ciao,
Torsten

-----Ursprungliche Nachricht-----
Von: questions-bounces at lists.ntp.isc.org
[mailto:questions-bounces at lists.ntp.isc.org]Im Auftrag von Uwe Klein
Gesendet: Sonntag, 15. Oktober 2006 17:01
An: questions at lists.ntp.isc.org
Betreff: [ntp:questions] Re: AW: Re: AW: convert_rawdcf: parity check
FAILED on my embedded Linux system


Torsten Krieger wrote:
> Hi Uwe,
>
> I made a small c program which reads the serial port /dev/refclock-0
> character by character, ntpd switched off. Shall I see one character by
> second (second = 1/60 minute) 0xf0 for low bit and 0x00 for high bit? If
> this should be the case then something went wrong with my serial
interface.
It has been a couple of years that i had contact with DCF and
I have never used this in conjuction with ntpd.

if the raw DCF carrier detection is used as RXD and
the serial line is configured properly raw, 50Baud 8bits/char no parity,
ignore parity and framing errors (IGNPAR) , break as zero ...
25 or 40 Baud worked better for me.
you should receive 1 byte ( or a framing error/break ) every second for 59
seconds
every 60 seconds.

100ms -->  5 Bit times -> 1 stop and 4 LSbit low, rest high -> 0xf0
200ms --> 10 bit Times -> 1 stop and 9 LSbit low, the high -> either 0x00 or
framing error
only jitter between leading and trailing edge is relevant.
The distance between acceptable low and high indicating chars is always big
enough.

uwe

ER Hmm: What do you receive?

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