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

From: Andre Devitt
Subject: Re: [Paparazzi-devel] UBX vs NMEA Protocol Inquiry
Date: Tue, 13 Mar 2012 13:36:37 -0400

I've worked with a GPS module based on the MTK3329 and am also
interested if there is a generic firmware supporting their binary

What I've found is that when manufactured some vendors of the 3329
module allow the customer to specifiy an NMEA one sentence message
with customized fields, and also specify a binary message field
similar to their one sentence NMEA.

This comes as an option the customer must pay for and I haven't seen a
way to enable the binary mode on the firmware that I've used. Trying
to switch the module to binary mode on a module manufactured without
the optional customization just resulted in a short chirp of binary
data and then continuation of the NMEA stream for me.

The docs on their binary protocol and one sentence customization are
out there on the web, but I don't know if there is an OEM firmware
that works. Please let the list know if you find one!


On Tue, Mar 13, 2012 at 12:49 PM, Jake Stewart <address@hidden> wrote:
> 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] -
>> [2] -
>> _______________________________________________
>> Paparazzi-devel mailing list
>> address@hidden
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> Paparazzi-devel mailing list
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