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Adafruit Ultimate GPS with N+2. Any experiences?


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#41 Homey

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Posted 18 April 2014 - 01:02 PM

Look at the PMTK command set for the GPS unit

http://www.adafruit....ts/PMTK_A08.pdf

There are actually four settings for how the unit starts up. I use a few of these in my system (aka Set update rate). After running for a number of hours my GPS Logger Shield finally got a good fix (with 11 satellites in view according to the GPGSV messages). With the backup battery installed it now seems to get a fix very quickly on a power cycle - sitting by a window. I still run it off a power supply (not USB).  I would definitely recommend using a backup battery with this unit but I did remove the RC circuit in my setup albeit good to know its an option.

Aye, misery loves company doesn't it. :)



#42 401kill

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Posted 26 April 2014 - 07:54 PM

Still no luck - I've got the low pass filter and backup battery, and tried on two different N+2 boards, but never shows any sign of getting a fix. It's configured for hot start and quickly obtains a good fix using both the gen-1 Netduino and a USB TTL connection.

 

Think I'm out of options - unless anyone has anything to add?



#43 DanielK

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Posted 02 May 2014 - 09:51 AM

this is really strange. If the GPS module works with an older Netduino than the module itself can hardly be the troublemaker.

And if a low-pass filter is installed in the GPS modules power supply ripple should also not be a problem. How do you set up the low-pass?

 

Daniel



#44 Jack Chidley

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Posted 03 May 2014 - 03:08 PM

IMHO the other options has been ruled out and power noise is what remains. There is a switching regulator (ST1S12GR, datasheet) on board and also the microcontroller itself is source of high frequency noise, so it seems some connection is picking that up.


Ahhhh... that might explain some problems that have driven me crazy too. I had the same problem with the GPS/Netduino that Daniel describes.

I have a Saleae Logic (fantastic) but I think that an oscilloscope might be a good investment.

Jack

#45 Jack Chidley

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Posted 03 May 2014 - 03:11 PM

this is really strange. If the GPS module works with an older Netduino than the module itself can hardly be the troublemaker.
And if a low-pass filter is installed in the GPS modules power supply ripple should also not be a problem. How do you set up the low-pass?


I think that the newer Netduino uses a switching regulator, older uses linear. A low pass filter uses an R C (Resistor Capacitor) circuit. See http://en.wikipedia....Low-pass_filter

Jack

#46 lirenaustin

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Posted 05 May 2014 - 12:15 AM

I have gotten the same problem. I have used my oscilloscope to see the noise from the Netduino broad. It looks that both of the 5V and 3V3 pins have the noise on them. The noise looks came from the microcontroller oscillator.



#47 Chris Walker

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Posted 05 May 2014 - 05:53 PM

Hi lirenaustin,

Which Netduino mainboard are you using?

Chris

#48 401kill

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Posted 07 May 2014 - 08:43 AM

And if a low-pass filter is installed in the GPS modules power supply ripple should also not be a problem. How do you set up the low-pass?

 

I used the same wiring layout as shown in your pictures previously:

 

Attached File  LPF.PNG   3.71KB   2 downloads

 

Which is really strange, because it works for you - but I've now tested it on 2 N+2 boards and get nothing at all!



#49 Jack Chidley

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Posted 07 May 2014 - 03:21 PM

Wow. There's a whole web site on interference. http://www.learnemc....-Tutorials.html

#50 lirenaustin

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Posted 09 May 2014 - 02:13 PM

I am using Netduino Plus 2. I have just tried to use Duracell rechargeable battery to power N+2 and connect GPS to 5V/3V3, but no lucky except separate the N+2 and GPS.  



#51 dino4net

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Posted 21 May 2014 - 11:42 AM

I have a similar problem with the MAX6371 chip in the moment.

When I power the chip from a battery it works perfect, connected to the Netduino 5V or 3.3V it's not reliable

 

 

Ok, my problem was because of the 3.3V Header. This is switched off for a short moment when the Netduino resets.



#52 pmb5

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Posted 30 July 2014 - 09:38 PM

Hi,

 

I've got the same problem here, when i power the GPS board fomr my Arduino it works fine, when i use the netduino 2+, even with the low-pass filter in this thread it wont lock on.  Any other experience?

 

Hopefully at the weekend I should have access to oscilloscope and someone who knows how to use it, see if mine needs a different filter setup.



#53 pmb5

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Posted 23 August 2014 - 09:00 PM

So now if I have the netduino2+ powered up trying to read GPS messages it stops me getting a GPS lock.  Does anyone know if the netduino2 has the same problem or is it just the 2+?

 

Also I'm using VS2013, and well i know it's experimental, but it doesn't seem very reliable compared to when i program my arduino.  

 

  • I probably get to program my n2+ once, then i have to unplug/re-plug it back in
  • debugging is SLOW, so slow I'm better off writing to the console.

I really want to work in c# because I can unit test all my code, use DI and simulate everything without needing the board, but at the moment working the the netduino is, well not fun :( I'm close to giving up with it. If i switch to vs c# express will the experience be slicker?






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