[time-nuts] M12+T ASCII interface - I'm confused?

[David C. Partridge]

Aren't potential terminating chars doubled up if in the datastream?

Check the protocol specification very carefully.

Cheers
Dave 

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Stephan Sandenbergh
Sent: 19 November 2008 14:30
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] M12+T ASCII interface - I'm confused?

Hi All,

Up until now we've been interfacing my Motorola M12+T's using the Oncore
software. However, at this point we are trying to have it interfaced
directly to a FPGA. To my mind this should be simple - the commands are
discriminated (framed) by looking at the start and terminating bytes
sequences when they enter the FIFO, check summed, decoded etc.

However, I noted something very peculiar about the motorola ASCII protocol:
The start bytes @@ and he terminating byte <CR><LF> aren't unique with
respect to the data bytes. For instance one could receive a time of 13hrs
and 10mins which would look identical to the terminating characters.
Initially I thought it made sense since the data is also sent in ascii
format. It appears not to be the case.