Re: [gpsd-users] An endian problem? - nevermind!

[Chris Howard]

Well, now I think I was wrong.
I'm not sure, but I think maybe the "od" program
was doing it.

I have written a bit of a parser and the everything coming
from the GPS looks fine.

Sorry to bother you.



On 10/16/2014 10:41 AM, Chris Howard wrote:
> 
> Hi,
> 
> I am new to gpsd and this may turn out to be the wrong place for my question.
> 
> I have a Trimble Resolution-T GPS which I have incorporated into a gps 
> disciplined
> oscillator, sort of a home-brewed Thunderbolt.
> 
> I'm looking at the TSIP data coming out of the thing.
> 
> First, let me say that the windows program which I downloaded from Trimble
> appears to talk to it just fine.  That's on my windows PC.
> 
> But my problem comes when I try to use a BeagleBone single board computer
> which is running debian linux.
> 
> So my lash-up is the Trimble Resolution-T GPS talking to the BeagleBone.
> The BeagleBone has multiple serial ports.  I am successful in talking
> to various other boxes through this same serial port.  I can use minicom,
> or other programs, seems to work ok.
> 
> I have two programs on the BB which claim to understand TSIP: ntpd and gpsd.
> Neither will talk to this GPS.
> 
> So I decided to drill down into the TSIP protocol a bit and see what's wrong.
> 
> I gathered some data directly from the serial port using cat into a file.
> I look at the file with 'od -x'.
> 
> Here's where we are getting to the strange part.  My packets only look right
> if I swap bytes:
> 
> dd if=<serial port>  of=gps.datafile  conv=swab
> 
> I am flummoxed.  Is there some config on the Resolution-T which will send
> data in swapped format?  Is there something really wrong with my BB serial
> port (seems unlikely)?
> 
> Ok... so I'm wondering if there is some way to do this byte swapping on
> the fly.  I created a named pipe (fifo) and put my dd command output
> there.  Gpsd didn't want to read from that because it's not a serial port.
> 
> Is there some way to get gpsd to read from a stream?
> 
> Resolution-T config?
> Can gpsd read from a stream?
> My own ignorance?
> 
> Thanks
> 
> Chris
> 
>