Xbee telemetry problem

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Xbee telemetry problem

Postby kempo » Sat Mar 15, 2014 8:34 pm

Good evening,

While using Gluonpilot v2 with Xbee 2.4 Ghz I have problems using telemetry.

The main issue is that, in the majority of cases, I cannot write a flightplan to the board using Xbee(I can Read from the Gluonpilot V2 but I cannot Write/burn/Auto-sync..).

It is very frustrating that i am going to the field and try to make some modifications on the flightplan uploaded from home and it is not working.

Today for example, the flightplan loaded from home was not on the wing direction and to change it it took a lot of time (several restarts of the laptop, multiple open/close of the groundstation, powered several times the autopilot....).

Can you advise me what to do in these cases ? How to debug the issue, what to follow,measure?

Thank you,
Alex
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Re: Xbee telemetry problem

Postby Tom » Sun Mar 16, 2014 9:25 pm

Hi Alex,

Do you experience the same at home on the bench?

Tom
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Re: Xbee telemetry problem

Postby kempo » Mon Mar 17, 2014 4:07 pm

Tom wrote:Hi Alex,

Do you experience the same at home on the bench?

Tom


Hi Tom,

In the majority of cases it happens outside.

It is something that i can measure (pin voltage or something else/ maybe it is an imperfect contact...) to see from where it is the issue?

Thank you,
Alex
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Re: Xbee telemetry problem

Postby Tom » Mon Mar 17, 2014 7:46 pm

There are AND gates used to multiplex the serial input.

Since your problem lies with the output, there is only a small resistor (82Ohm if I'm not mistaken, R18), to limit the current. You could try to short it.

As an alternative test you could try to connect a USB cable and see if the XBee works, or the USB signal works...
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Re: Xbee telemetry problem

Postby kempo » Mon Mar 17, 2014 9:17 pm

Tom wrote:There are AND gates used to multiplex the serial input.

Since your problem lies with the output, there is only a small resistor (82Ohm if I'm not mistaken, R18), to limit the current. You could try to short it.

As an alternative test you could try to connect a USB cable and see if the XBee works, or the USB signal works...


With the USB cable connected directly to the dedicated port from the board I have the same random problem.

By R18 you mean the resistor market below ? I should remove it and connect directly the 2 pads ( a drop of solder)?

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Re: Xbee telemetry problem

Postby Tom » Tue Mar 18, 2014 12:22 pm

Yep,

R18 and R19 are only there to limit the current in ESD situations... In the previous versions they were not there....

Always worth a try to see if it makes a difference :-)
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Re: Xbee telemetry problem

Postby kempo » Tue Mar 18, 2014 6:08 pm

Tom wrote:Yep,

R18 and R19 are only there to limit the current in ESD situations... In the previous versions they were not there....

Always worth a try to see if it makes a difference :-)


Thanks for the advices but before going on this "road" I want to have some feedback from other users -persons that are using Gluonpilot V2 and 2.4 ghz Xbee ( http://www.buildyourowndrone.co.uk/Ardu ... el-kit.htm ) , if they encounter the same issue.

Due to the fact that i have 2 left hands it will be very easy to remove the resistors, but it will be very hard to put them back...

Thank you,
Alex
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Re: Xbee telemetry problem

Postby kempo » Mon Mar 31, 2014 5:31 pm

Hi Tom,

Small update : I have replaced R18 with a blob of solder and now it seems that the telemetry works better.

I will do more tests and come with feedback.
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Re: Xbee telemetry problem

Postby Tom » Mon Mar 31, 2014 5:59 pm

Strange... the resistance is really low already at 85Ohm.

Keep us updated. If you no longer have this problem I will change the resistor with a smaller value in the next release!
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Re: Xbee telemetry problem

Postby Tom » Tue Apr 08, 2014 6:17 pm

Has it been fixed? I think I might have found a bug...
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