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Author Topic: Design questions GPS-Raspberry-Wifi-mediaDROIDX  (Read 3094 times)

Justme

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Design questions GPS-Raspberry-Wifi-mediaDROIDX
« on: April 22, 2017, 02:18:34 PM »
Hi there!

I am building a location-based media system for a vehicle by using GPS, Raspberry PI, and mediaDROIDX player. So I watched the tutorial from DigitalSignage a few times (... video_tutorials.html?videoNumber=locationBasedPro), and also Googled around to understand how this all should be done.

I want to configure the mediaDROIDX in a local LAN to get the GPS coordinates from the Raspberry (sendLocalCommand), which will in turn get media updates from the Cloud server when the vehicle is back in Wifi range at the home base.

The Raspbian image made available by DigitalSignage assumes attaching an Adafruit Ultimate GPS HAT to a Raspberry PI2, which in turn will be the Wifi Access Point for the media player and the Wifi Router for media updates from the Cloud server.

GPS
Instead of attaching an Adafruit GPS HAT to the Raspberry, I want to use a USB GPS Receiver on a 1-2m cable such as the MG-220 or Columbus V800. These devices also send data as per NMEA protocol the same as the Adafruit Ultimate GPS HAT from the tutorial, but via USB and not UART.
1. Is there any known problem with using a USB GPS Receiver on the PI?
2. Is there a recommended USB GPS Receiver for this? An accuracy of <5m and cold start of say 30secs is fine.
3. Is there any changes to be made to the getgps.js script?
4. Will the cgps command work with getting GPS coordinates from USB instead of UART?

Raspberry PI
The tutorial recommends using a PI2, but that model is outdated and does not have built-in Wifi. Also, according to the Adafruit GPS HAT article, it will not work on the PI3 (other articles mention some workaround). Note that the image from DigitalSignage assumes PI2 and Wifi AP+Routing.
5. For data link reliability, I am thinking of connecting the Raspberry to the mediaDROIDX with an Ethernet cable and Eth/USB-OTG converter, instead of Wifi AP. Is my assumption correct that it will make no difference for GPS coordinate data transfer, for example via sendLocalCommand? Any recommended Ethernet/USB-OTG converter?
6. Even if using Ethernet cable, I still need Wifi Routing capability for media updates from the Cloud server. What is recommended to get this on the PI2?
7. Since I intend to use a USB GPS Receiver, is it safe to use the PI3 anyway as it has built-in Wifi that can be configured for Routing? Can I still use the same Raspbian image from DigitalSignage for this?
8. Can I use a Raspberry PI Zero W instead (and also use the same Raspbian image from DigitialSignage)?

Any help is much appreciated!


admin

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Re: Design questions GPS-Raspberry-Wifi-mediaDROIDX
« Reply #1 on: April 24, 2017, 02:47:09 PM »
1. Is there any known problem with using a USB GPS Receiver on the PI?
you can use any GPS device and the JavScript send will remain the same.

2. Is there a recommended USB GPS Receiver for this? An accuracy of <5m and cold start of say 30secs is fine.
I don't have specific hw to recommend but any will be just fine!

3. Is there any changes to be made to the getgps.js script?
script remains the same as it is not related to the hw at all.

4. Will the cgps command work with getting GPS coordinates from USB instead of UART?
all remains the same.

The tutorial recommends using a PI2, but that model is outdated and does not have built-in Wifi. Also, according to the Adafruit GPS HAT article, it will not work on the PI3 (other articles mention some workaround). Note that the image from DigitalSignage assumes PI2 and Wifi AP+Routing.
For data link reliability, I am thinking of connecting the Raspberry to the mediaDROIDX with an Ethernet cable and Eth/USB-OTG converter, instead of Wifi AP. Is my assumption correct that it will make no difference for GPS
correct, no difference.

6. Even if using Ethernet cable, I still need Wifi Routing capability for media updates from the Cloud server. What is recommended to get this on the PI2?
Best to google for that.

7. Since I intend to use a USB GPS Receiver, is it safe to use the PI3 anyway as it has built-in Wifi that can be configured for Routing? Can I still use the same Raspbian image from DigitalSignage for this?
Yes you can, our script just uses tcp/ip to send command to the player, it doesn't matter the origin or device its running on.

8. Can I use a Raspberry PI Zero W instead (and also use the same Raspbian image from DigitialSignage)?
yes you can



Justme

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Re: Design questions GPS-Raspberry-Wifi-mediaDROIDX
« Reply #2 on: May 12, 2017, 04:47:43 PM »
Thanks Admin, that was very helpful!

So I purchased the PI3 and installed O/S and GPS functionality from scratch: Raspbian, networking incl dhcpd, xrdp (for Remote Desktop), samba (for copying files from Windows to PI), wifi connectivty, nodejs (from NodeSource), gpsd, and even Navit with OpenStreetMaps to verify accuracy of GPS receiver. It all works very well. BUT.... 

Now I got stuck with the getgps scripts from DigitalSignage. I only found nodeLocationClient.js on Git Hub. But when I run that on the PI, it rains error messages because of missing scripts. Where can I download these: getgps.js, getgps.py, and also other scripts I would need (module.js, jsonp-client... etc).

I know there is a ready-made image available from DigitalSignage, presumably with all these scripts included, but I got so far already with the Raspberry PI configuration myself that I prefer to finish it without the ready-made image.

Please help, thanks!

admin

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Re: Design questions GPS-Raspberry-Wifi-mediaDROIDX
« Reply #3 on: May 14, 2017, 06:40:32 AM »
All that you need is just the sendCommand.js script as our player expects the post of GPS coordinates and does not care from which device they come.

Justme

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Re: Design questions GPS-Raspberry-Wifi-mediaDROIDX
« Reply #4 on: May 14, 2017, 04:15:21 PM »
Where can I get /root/gps/getgps.py? Is this part of some Python library? Getgps.py is executed from nodeLocationClient.js which in turn calls the sendCommand function (either sendLocalCommand or sendRemoteCommand).

admin

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Re: Design questions GPS-Raspberry-Wifi-mediaDROIDX
« Reply #5 on: May 14, 2017, 06:45:14 PM »
You can download the files from here: http://www.digitalsignage.com/files/getgps.zip

Craig K

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Re: Design questions GPS-Raspberry-Wifi-mediaDROIDX
« Reply #6 on: May 17, 2017, 12:28:46 PM »
I am an extreme novice to Raspberry Pi3 but can follow detailed instruction on most hardware and software. My Linux knowledge is low. Can someone provide me with detailed instruction how to set this up from start to work? I want to use this application to plug into different LED's on the fly using all the functions of DigitalSignage.com

 

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