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Permalink Reply by Mogly (Umesh Tharanath) on August 18, 2009 at 12:33pm

Does any one know or writen custom/builtin Serial program code for 9Xtend?
Like
servo actions, motor, video streaming, Chat window. or file transfer ...

let me know.. Thanks, Mogly

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Permalink Reply by Noth666 on August 20, 2009 at 9:36am

I've now found a "solution" for this, but it will kick up the duty cycle above the allowed 10% (not a bad thing in everyones eyes).

I wrote a small program which just basically simulates sending servo position update packets via the XBee 868 to a receiver unit. What I tried out now is to simply reset the modem and wait for a small moment before retransmitting data, between every full update packet.
Of course this is not optimal, it should not reset so often etc, but I did it like this to test the theory with minimal work.

And it works like clockwork, but it does have a delay between payloads and thus is slower than it would be without the reset and delay. So I will work on an optimal transmit loop count between resets based on my payload, and anyone else could do the same.

To reset the modem connect a cable between the RST pin on the adafruit module and one of the digital pins on the Arduino/ArduPilot.

Then just simply add this:
in void setup()
pinMode(resetPin,OUTPUT);
digitalWrite(resetPin,HIGH);//set the RST pin high, low will reset the module

And then in the loop code with apropriate counter (you can find this out easily if you transmit a same size payload every time, otherwise make it low enough to be safe - otherwise use response ACK packet timeout to activate)
delay(TXdelay);//wait for data to transmit
digitalWrite(resetPin,LOW);//press reset
delay(RSTactiveDelay);//spec minimum is 100us to register
digitalWrite(resetPin,HIGH);//release
delay(RSTrecoverDelay);//wait for XBee to initialize

Of course you'll need to tune your variables for your particular application, and define them.

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Permalink Reply by limaiem on December 31, 2009 at 6:32pm

Great job Noth666
I was searching how to hack this 6 minutes wall :)
Thank you !

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Permalink Reply by Kim Halavakoski on November 21, 2010 at 9:42am

Hello,
has there been any progress with this duty cycle issue with the 868:s? Has anyone tested the "solution" by Noth666?
Does it work reliably?

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Permalink Reply by James Turner on November 21, 2010 at 11:58am

HI Kim,
I don't think there can be much more progress with the duty cycle problem other than resetting the device from time to time as it's a restriction imposed due to the frequency it uses. I personally have not tested the exact solution posted by noth666 because I fly using PIC32 but process I use is exactly the same and it works just fine. If I'm only using one way comms for servo control then my Lipo's run out long before the duty cycle is ever a problem @ 9600bps so I leave resetting off. I have had a good 12 months of flying with these modules alone (no standard TX) and have never had a crash caused by duty cycle problem so it seems reliable enough. the only modification I did use was to fit a small heat sink on the chip, I could never decide it if actually made much of a difference with the power I had it set too but fitting one is never a bad idea.

Regards,
James

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Permalink Reply by Dorulet on November 26, 2010 at 7:33am

Which would be the reset "pin" on the XtreamBee Adapter?
http://store.diydrones.com/product_p/br-0015-01.htm
I looked pretty well at the markings on the adapter but there is no RESET or RST pin...

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