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401kill

Member Since 09 Oct 2013
Offline Last Active Dec 22 2018 06:05 PM
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Posts I've Made

In Topic: Adafruit Ultimate GPS with N+2. Any experiences?

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!


In Topic: Send data from netduino 2 plus to a Service with xml serialization

07 May 2014 - 08:32 AM

RESTful services will get you up and running, but URLs have a maximum length.

 

Correct - so if you are sending a lot of data, send a POST request with the message body containing JSON (or similar) serialized data. The max POST size is defined by your web server, not by the HTTP spec (and is usually adjustable).

 

XML serialization is anything but short! :) JSON is more lightweight, so faster to process and transmit. Less RAM usage too.


In Topic: Send data from netduino 2 plus to a Service with xml serialization

26 April 2014 - 11:47 PM

For my project (somewhat similar, N+2 reporting to a WCF web service), I tried to use DPWS. Sending a request worked fine, but  the firmware doesn't implement the XmlReader class, so DPWS can't deserialize the response. This might work for you if your service calls are one-way only.

 

As jrlyman3 said, XML generation is comparatively slow due to the verbosity of the language. I configured my WCF services to use JSON instead (exposed via RESTful URLs), and used Json.NetMF to (de)serialize the data sent / received.

 

I did eventually end up forking the library to strip out the bits that I didn't need, but its a good starting point.


In Topic: Adafruit Ultimate GPS with N+2. Any experiences?

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?


In Topic: Adafruit Ultimate GPS with N+2. Any experiences?

11 April 2014 - 10:11 PM

currently my N+2 with the Adafruit Ultimate GPS is working in 99% of the tests. I added a low-pass filter (10 Ohm resistor/47nF capacity) into the power supply and now I get a sat fix in most cases. Also, I have the backup battery installed which somehow makes the whole thing more stable.

 

Thanks for the heads up!

 

How much would you say having the battery increases stability by?

 

I've implemented a low-pass filter as you described (10 ohm in series with the GPS, 47 nF in parallel), and it has improved things (it sometimes works now!), but it is still very unpredictable.

 

As far as I can see, your implementation using the battery is the only significant difference.

 

Attached File  WP_20140412_038.jpg   298.85KB   1 downloads


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