Re: [Paparazzi-devel] UBX vs NMEA Protocol Inquiry

[Jake Stewart]

I've got a spare Fastrax UP501 module.  It uses the MediaTek 3329 chipset. 
(same chipset as ArduPilot modules)

There's probably a way to set it to use the MTK binary protocol.  Fastrax has 
created a custom firmware though and there's no mention of anything but NMEA in 
the manual.  I might have to see if I can get the OEM firmware and risk 
flashing it.  As far as I can tell all fastrax does is mount the mediatek to a 
board and upload a custom firmware.  There seem to be a lot of MT3329 chip 
based modules out there.  I'll try to contact fastrax and mediatek and see 
what's going on.  There must be an OEM firmware kit out there since it seems 
like everyone has a custom firmware.

I'm really not to the point of worrying about the GPS just yet and probably 
shouldn't have jumped in to the discussion about NMEA.  But I see lack of NMEA 
support as somewhat of a shortcoming since every GPS I'm aware of uses it.  I'm 
more than happy to work on the parser when I get to that point.  Maybe there's 
more uBlox GPSes out there than I thought, but I'd never heard of them prior to 
Paparazzi.  They don't seem to be available through standard distribution 
channels (digikey, arrow, etc.).  As a percent of total GPS units, uBlox in 
binary mode must be a very small percentage of the total.

Chris suggested they're one of the big three, but it looks like they were 
ranked 6th out of GPS chip manufacturers (at least in 2009).  In the last 
article I read Sirf and broadcom owned 90% of the market with the other 8 or so 
manufacturers spliting the remaining 10%.

None of that really matters as NMEA is the standard and will be here to stay.  
If a slightly different driver for each unit is required due to space 
limitations that should not be difficult to do.  Between configuring the module 
and tweaking the driver it should not be hard for paparazzi to support every 
GPS out there.

Gareth, thanks for pointing out another way Megacorp (diydrones) is trying to 
lock out competition.  It really looks like they're trying to capture the 
market and then shut everyone else out.  Looks like they have anti-clone code 
on the AP software and the GPS units. They'll probably be doing it with IMUs 
soon, if they already haven't.  Kind of funny that they wrote their own binary 
protocol just to lock people out when there already is one for the chips 
they're using.  Doesn't get much more obvious than that.


-Jake


> ----- Original Message -----
> From: Gareth Roberts
> Sent: 03/13/12 04:07 AM
> To: address@hidden
> Subject: Re: [Paparazzi-devel] UBX vs NMEA Protocol Inquiry
> 
> Hi Jake,
> 
> What GPS do you have? Maybe you could create a binary driver for it 
> instead? There are already drivers for UBlox, MediaTek and SkyTraq.
> If your GPS is supports one of the popular binary protocols (SIRF for 
> example) it could be really useful, and possibly simpler than getting the 
> NMEA parser working.
> 
> Getting NMEA working for a single case GPS (or even vendor) should be 
> possible, but for more information on why it's very difficult to write a 
> general NMEA parser see [2].
> 
> > I do have to get a NMEA GPS working since I don't have the luxury of 
> > using an oddball, esoteric GPS protocol.
> 
> You may be interested to know the GPS for the latest version of ardupilot 
> actually outputs an ardupilot specific protocol, only available on GPSs 
> purchased from their store [1].
> 
> Cheers,
> Gareth
> 
> [1] - 
> https://store.diydrones.com/MediaTek_MT3329_GPS_10Hz_Adapter_Basic_p/mt3329-02.htm
> [2] - http://esr.ibiblio.org/?p=801
> 
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