Re: [gpsd-users] GPSD 3.5 has shipped

[Ed W]

On 17/04/2012 15:52, Eric S. Raymond wrote:
> Go right ahead and add all the sentences you want.  But I won't take a
> patch that doesn't do the *whole* job for each one - and that means not
> just the fun, easy part at the NMEA driver level but the hard part,
> the JSON marshalling and unmarshalling for the clients.  And the
> documentation.

Please have a look at their code.  I think it's elegant and self 
describing:
    
http://opencpn.git.sourceforge.net/git/gitweb.cgi?p=opencpn/opencpn;a=tree;f=src/nmea0183;hb=HEAD

I'm rather hoping that the long term for gpsd would be that it could be 
kicked into similar shape such that translations could be done like 
this.  With some automated processes the documentation can be extracted 
from the source files (which means it's much more likely to be maintained)

Please give some thought as to whether you could incorporate this?


> > I'm not sure that I yet understand how NMEA2K will fit into all of
> > this - do you have some sketch outlines of what you are looking at?
> > What kind of interface hardware? Quite interested to see how this
> > progresses!!
> Support for reading CAN frames from a controller card has been accepted
> into the Linux kernel.  We get to assume we can read CAN frames from a
> special socket, leaving us with the job of recognizing and unpacking NMEA2000
> frames. At that point it's almost like handling a new type of binary GPS.

Depends on your long term goal, but this will be *EXTREMELY* hard to get 
NMEA2K certification this way.  The sticking point is that NMEA2K 
devices need to be certified with *exact* equipment and software known.  
So lots of people have expressed dismay that the only way to connect a 
computer to an nmea2k network is to get it certified with an exact 
binary image of the software installation - no bug fixes or patches are 
possible without loosing certification...

Clearly you can pretty much stick a vanilla CANBUS controller onto an 
nmea2k network and be done with the certification issues, but I'm not 
sure this ever takes us anywhere other than "hackers"

Possibly a more interesting option is the NMEA2K certified adaptors from 
the likes of Actisys.  This is the workaround where you get a piece of 
hardware certified and then talk to the hardware over usb or something 
that isn't nmea2k - I think we will see this trick used widely as 2K 
gets more popular.

The Actisys bridge is pretty cheap as well and I believe has linux 
drivers, so my vote would be to look at that route for support?  I will 
sponsor a device for anyone who will actively code support? (disclaimer, 
no relationship with actisys, but they are based in the UK and I have 
met some of the folks in the past)


Regards

Ed W