Re: [Paparazzi-devel] custom autopilots

[Andre Devitt]

I can chime in about the NMEA parser. I've been working with some
folks using a mediatek GPS and we've brought the NMEA parser to a more
usable level.

We added support for  satellite signal level reporting (GPGSV msg),
as well as parsing heading, and speed. I'd be happy to submit a pull
request if it'll help out. I also added the gps type "nmea" and
associated files to the new software build system.

I do agree with Felix's thoughts on NMEA not being the nicest
protocol. It's likely that the sirf binary protocol isn't that
different from ublox, it might be worth looking into using it instead.
The ublox parsing code could probably be used as a template for sirf.

Protocol info is here: here
http://www.usglobalsat.com/downloads/SiRF_Binary_Protocol.pdf

We have some other hardware support that we'd like to contribute as
well so contributing the nmea code might be a good start for us to
figure out the process.

Andre

(finally found mediatek binary specs last night and may implement at some point)

On Wed, Jan 12, 2011 at 10:50 AM, Maikel Punie <address@hidden> wrote:
> maybe i should have a look at those boards then,
>
> any sugestion on what board? since i have no idea what board to use.
> about the gps: it supports nmea or SirfBinary format, but it seems that the
> sirf binary format is not supported,
> What about the imu on i2c should it be possible to integrate that one?
>
> Maikel
>
> On Wed, Jan 12, 2011 at 16:38, Felix Ruess <address@hidden> wrote:
>>
>> Hi Maikel,
>>
>>>>
>>>> What limitations do you see? Any hw/technical limitations or is this
>>>> more concerned with availability?\
>>>
>>> buying another board an all new hardware,
>>> we already have all the hardware (except the failsafe rc part)
>>>
>>> so if we are going with a paparazzi board we will need to drop all out
>>> hardware and start over, or is there a possibility to integrate our own
>>> modem, gps servo controller and stuff with the paparazzi boards?
>>
>> Of course you can integrate your modem and GPS with paparazzi.
>> - Modem should be trivial (probably nothing to be done here at all as long
>> as your modems can provide a transparent, serial-like, link and don't need
>> any fancy in-the-air configuration).
>> - GPS should not be a really big deal either (although the paparazzi NMEA
>> parser is not really good and nobody uses it afaik). So you would probably
>> want to have a look at the parser and make sure it works always and does not
>> hang up on unexpected packets. NMEA is not really nice in my (and a lot of
>> other peoples) opinion anyway.... but that is not the point here of course.
>> - Your servo controller you would very likely not need at all, since that
>> is already directly on the paparazzi boards.
>>
>> Nevertheless, personally I think it would be nice to have support to run
>> all the paparazzi stuff in linux userland. That being said, I don't think
>> this is a very good idea in a lot of cases. (You loose tight control over
>> timing, you should probably use a RT linux, etc.)
>> Imho it often makes more sense do do the sensor interfacing and fast
>> estimation/control loops directly on a dedicated board and only do higher
>> level (navigation, payload, perception, etc.) on a (especially when it is a
>> non-realtime) linux board.
>>
>> Cheers, Felix
>>
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