Re: [gpsd-dev] Getting the driver-switching logic right

[Andy Walls]

On Thu, 2013-10-17 at 09:50 -0400, Eric S. Raymond wrote:
> Andy Walls <address@hidden>:
> > Actually the MT-3329 will probably gracefully accept the existing
> > sentences the MT-3301 emits.
> > 
> > 1. $PMTK320 is unsupported, so the unit should respond with a NAK
> > $PMTK001 sentence to it.  I will need to test.
> > 
> > 2. The difference in $PMTK300 is the two '0.0' vs. '0'.  I will need to
> > test if the unit will accept '0.0' values.
> > 
> > 3. For $PMTK314, I had tested my unit previously. The unit will silently
> > accept enabling periodic reporting of messages that aren't supported.
> > It simply doesn't generate reports for the unsupported messages.  So my
> > change there is unnecessary.
> 
> I would welcome a patch that quietly supports both variants and explains
> what the relevant differences are in comments.

Hi Eric:

Testing reveals that the Trimble Condor (assumed MT-3329 device) does
not need any changes to the $PMTK sentences currently emitted by gpsd's
MT-3301 driver.

The chip positively acknowledges all sentences as valid.

The chip appears to ignore MT-3301 $PMTK sentence fields that are not
implemented in the Trimble Condor.

I assume the chip is ignoring the $PMTK320 sentence, which the Trimble
Condor don't mention.

I don't see a need for a gpsd patch changing the emitted $PMTK sentences
at this point. 

Regards,
Andy