Discussion for the Tau Labs android application
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pug398

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xbee and android gcs

by pug398 » Tue Apr 15, 2014 1:11 pm

Currently xbee radios are working with the pc based gcs (fast) but I am having a little problem with android gcs. Haven't spent a lot of time on the problem yet but thought I would ask if anyone has ideas to speed up the troubleshooting process. Serial connection opens, connects and data is transferred but stops at loading the uavo set or at least never said it loaded. The settings are 57k 8,N,1 no flow control both sides and as of a few days ago android app was connecting with bluetooth and 3dr radio links on two different devices. So far looks to be the fastest, most solid link yet and would like to get the android app connected.
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Re: xbee and android gcs

by peabody124 » Tue Apr 15, 2014 1:31 pm

So my prediction would be that if you go to the browser and hit the firmware IAP object a few times that eventually it will show something other than zeros and it will work. Can you confirm this?

I see the same issue. I need to dig into why object requests fail so much with 3dr radio. My theory is it doesn't do well with bidirectional data.

Multiple people (myself included) see the same problem with GCS. Do you see the system health gadget ungray quickly too, or does that take a while?

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Re: xbee and android gcs

by pug398 » Tue Apr 15, 2014 3:11 pm

I will see what I can find out for you later today. I didn't think anything showed up in the android browser but will check it out. Perhaps there is data overflow at beginning. When connected to pc GCS the objects appear to have as fast throughput as usb with these radios.

Is android app interface rate fixed at 57k?
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Re: xbee and android gcs

by peabody124 » Tue Apr 15, 2014 9:56 pm

It's not that the rates at different. It is that android ignores all objects until it is fully connected. That is because it waits until it knows the firmware running on the board and then loads up the appropriate objects.

This is good and bad:
- The good news is that it makes it compatible with lots of versions of the firmware.
- The bad news is it needs that information to become functional
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Re: xbee and android gcs

by pug398 » Wed Apr 16, 2014 12:42 am

As far as pc GCS goes it seems 100%. It downloads objects as fast as wired and health monitor goes active in about 4 seconds. A few short flights and it never dropped any data. Doesn't appear to be any interference on 2.4ghz at least not that I see so far. It is still not functional with android but there were a couple of hitches. The transceiver module requires ~250ma and some adapter cables don't have all pins connected and also some trickle chargers don't supply that much current. Apparently I was mixing these components trying to get it to work. Bottom line with enough power to the module and good serial connection it will connect and transfer lights blink but does not finish the job I guess from what you say. As you said all 0's in browser and never does show any different. Lots of radio settings but from the data sheet don't see anything that stands out. The upload/download arrows go to about 1020/60 with initial connection and stay there.
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Re: xbee and android gcs

by pug398 » Wed Apr 16, 2014 1:39 pm

It seems the N7 never wants to completely load all the objects unless you do a cold boot each time and even then it is intermittent. The galaxy S3 works as well with xbees as it did with 3dR radios but the point was to improve. Going to bypass the android serial interface with a xbee-ttl-bluetooth bridge and see what that does.
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Re: xbee and android gcs

by pug398 » Thu Apr 17, 2014 12:44 am

Well that made a difference. The portable xbee-bluetooth bridge seems to be working well. Very few transmission retries in GCStelemetry stats. Will give it a distance test here in the next few days and check for interference. Everything is on 2.4Ghz which is a little scary. Ended up not needing anything between the modules since Bluetooth module had the uart already and all I had to do was plug it into the Din/Dout, 5v and grnd lines on xbee adapter. Then just plug xbee usb adapter into usb power pack. Clean setup. The 3dr should work the same just connect Bluetooth uart to the rx/tx lines of Hope radio module and get 5v from usb.
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Re: xbee and android gcs

by peabody124 » Thu Apr 17, 2014 3:21 pm

OK sounds like I need to do some digging this weekend then. Maybe something isn't optimal with how I handle the serial port. That cold reboot issue also implies I don't close the port properly. Is that reproducible with N7 but not with Galaxy?

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Re: xbee and android gcs

by pug398 » Thu Apr 17, 2014 7:27 pm

I don't know how you find the time to do all you do. Do you ever sleep? :)

The N7 seems to always require cold boot to connect and the S3 does not. The N7 has never loaded the full set while the S3 will eventually end up talking to me. This is with xbee. With 3DR they both eventually load the objects after a delay and talk. The 3DR seem to lose some data during session. Both devices seem to work fine with radio bridges with the xbee appearing to be the fastest (not necessarily the best). Using both will determine which is best at medium range. I am still reading all your old posts regarding this.
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Re: xbee and android gcs

by peabody124 » Fri Apr 18, 2014 12:50 pm

Could you actually do me a favor. Create a github issue for android connectivity and make a table listing your various results for 3dr/xbee/BT tests. That way when I sit down to work on it I have the information organized in one place.

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