neo7"mini" variant will not work

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strgaltdel
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Joined: Thu Jan 05, 2017 6:48 pm
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neo7"mini" variant will not work

Post by strgaltdel »

Hi,

after building app. 10 Sensors, using GPS devices like neo7"mini", neo7, neo m8n it's the first time i run into trouble.

my last buy of a neo7 "mini" was this kind of type
www.ebay.de/itm/Mini-GPS-Ublox-7-Series ... OSwnHZYQJE~
i'm not able to operate this gps, easy to be identified by the single wire connectors, together with openXsensor
i connected the gps to three Ardus, all worked properly with older "minis", which had futaba like connectors, without success.

suprisingly the GPS worked together with Ublox software without problems.

i can rule out
- Arduino wiring problem
- GPS connector problem
- wrong openxsensor configuration

only thing i'm worrying about is, that by connecting this gps to a nano, the RX led is blinking very slow.
Usually a working gps generates a blink frequency from app. 5hz
This one is about 2hz, like on a not gps configured ardu, so i would think the "initial commands" send to the gps are not supported by this kind of neo7.

are there cheap "OEM" neos on the market which are not supported by oXs ?
any suggestions?

thanks for advice
udo

Carbo
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Joined: Fri Aug 02, 2013 6:55 pm
Country: Germany
Location: Freinsheim RP

Re: neo7"mini" variant will not work

Post by Carbo »

Are you using the actual oXs version with split config files? If so,can you try with an earlier oXs version.
strgaltdel
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Joined: Thu Jan 05, 2017 6:48 pm
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Re: neo7"mini" variant will not work

Post by strgaltdel »

The problem occured by using an "old fashioned" firmware, app. 18Month old (-;
i tried Rev 8.01 too, getting the same result.
https://github.com/openXsensor/openXsen ... _Downloads

My bet is, that this "special kind" of gps doesn't accept the initial commands, given by these firmwares, to set it into a oxs-ready defined state
today i recognized that these devices sometimes are advertized "without compass rc309"
maybe this is producing incompatibility ?

...Didn't follow the actual developments and assumed Rev8 is the newest one
mstrens
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Re: neo7"mini" variant will not work

Post by mstrens »

Perhaps this kind of gps has been configured in order use a different default configuration.
At startup oXs expect that the gps communicates at 9600 bds (and oxs sent some commands to force a specific oXs config (disable nema message, activate ublox messages and change bauds rate to 38400).

I suggest that you first check the baud rate used by the gps when it is just powered on and not connected to oXs (it should be 9600 bauds).
To test it, best is to use a logic analyser.
If you do not have a logic analyser, you could make a test with a USB/serial (FTDI).
Connect GPS to FTDI and open an IDE terminal session(or another PC terminal software). Set the baud rate of the terminal session to 9600 and if the GPS uses the standard default config, you should get some readable text on your PC terminal session.

There is also a ublox program that you can download (free) in order to modify the config. You can try using it to check your GPS config.
Carbo
Posts: 467
Joined: Fri Aug 02, 2013 6:55 pm
Country: Germany
Location: Freinsheim RP

Re: neo7"mini" variant will not work

Post by Carbo »


strgaltdel
Posts: 8
Joined: Thu Jan 05, 2017 6:48 pm
Country: -

Re: neo7"mini" variant will not work

Post by strgaltdel »

Thanks for assistance !

I checked the default Baud rate by using putty: it's the usual 9600.

Furtheron i gave the Ardu a fixed 5.5V Source to rule out, that a "bad supply" would lead to signal levels "on the edge".
(but guessing the neo works with 3.3v too?)

Next step was to modify the oxs_gps.cpp
I changed the delay from 1000 to 2000 to give the gps some more boot time.

All steps without any success.

Now i will read the Ublox center docu how to configure the device by the tool and check if it's real changeable or if it has a lock mechanism to prevent any changes.

It's a little bit the "you get what you pay for" story
These devices would perfectly fit to the "cheap opensource sensor" agenda, cause it's less then 9 Euros.
But it seems to be too cheap (-;
Maybe i'm riding a dead horse

What i worry about is, that newcomers will have to pick the right choice which "mini" they have to buy.
actually i would say "take the one with compass included"



thanks and regards
Udo
strgaltdel
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Joined: Thu Jan 05, 2017 6:48 pm
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Re: neo7"mini" variant will not work

Post by strgaltdel »

Obviously the device parameters can't be changed

i had no problems to change baud rate from the older one GPS's by using u-center
(different rates cross-checked with putty)

The newer ones (without compass) stay on 9600, independent from what u-center sent to the device. :o
Also, the typical poll function to see the actual config after booting wasn't executed.
Tried the actual and an older one u-center revision.
mstrens
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Re: neo7"mini" variant will not work

Post by mstrens »

That is strange. I do not remember that it was possible to lock a Ublox to a configuration.
strgaltdel
Posts: 8
Joined: Thu Jan 05, 2017 6:48 pm
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Re: neo7"mini" variant will not work

Post by strgaltdel »

Maybe that's the cause:
https://www.u-blox.com/en/counterfeit-p ... and-misuse

another odd description :
"GPS is customized for NAZE32/F3 Flight control board
Internal Ublox 7 series chip core of manufacture OEM"

In case you're interested in further investigations i can send you a sample for free.


I came to the result to order some new mini GPS's from another source, assuming these will work.

regards
Udo

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