Unable to communicate with airplane side xbee modem

[Bryan K]

I have been researching this all day and I cannot figure it out.

 

I bought the Xbee kit from DIY Drones a few weeks ago, and the system worked great right off the bat, but now I am having problems with it. I downloaded X-CTU and I was able to get in and connect to my computer side Xbee, but I am unable to connect to the plane side Xbee. I have tried every different baud rate, but no luck. I have tried to test, write and read, but no luck connecting. I have been trying to go through the forums and figure out what is wrong and how to fix it, but I cannot find the right forum or it doesn't exist. Please help me figure out what I need to do.

 

P.S. The RSSI light stays lit on the USB Xbee adapter on the Xbee that I can't connect to, but not on the one I was able to connect to. Is this normal or is it significant?

[Rigel]

That's what happened to the first adapter I soldered...totally useless too because solder clogged the holes, which is why I ended up soldering the headers with the modules attached.  I've tried removing them but it's next to impossible with a soldering iron.  I guess a hot air station may do it.

[Toby Mills]

Sounds like you are using way too much solder or taking too long to solder the pins.

Soldering pins should be done very quickly, try not to heat the pins themselves too much.

Gently touch the iron on the pin so it is only just touching the pin, immediately touch the solder on the iron between the iron and the pin and then melt the solder onto the pin by pushing the solder 'through' the heat of the soldering iron onto the pin.

This should happen very quickly (around 1 second). The relative coolness of the pin solidifies the solder before it travels too far. If you heat up the pin too much then the solder stays molten and can travel. Don't preheat the pins. Use the soldering iron to heat and melt the solder not the pin and use the iron to guide the solder onto the joint. The pin should only be hot enough to let the solder get to where it needs to then solidify quickly. If it is taking more than about 1 second per joint to solder a pin, then you are likely using too much head and heating the wrong part.

Once the solder is in place, lift the soldering iron vertically and flick it quickly up the length of the pin, this will leave a nice teardrop solder finish. The solder should solidify almost immediately after removing the heat (the pin conducts the heat away as it is relatively cool). If it blobs or leaves a mess, then your soldering iron may not be clean.

It shouldn't matter whether the XBee is in the header or not, solder should not get anywhere near that far into the connector. Beginners should probably not leave the Xbee in the header, as too much heat could damage it.

Here is a userful video...

http://www.youtube.com/watch?v=x0YxEilyQVY

[Rigel]

I contacted DIYdrones store and apparently you can unbrick the Xbee while attached to the adapter.  You'll need an FTDI cable if you're having a problem with the plane side Xbee. 

Go through the unbricking procedure found at the bottom of the manual here: http://code.google.com/p/ardupilot-mega/wiki/Wireless

When you get to the Action needed window you can reset the adapter by grounding the RESET pin on the adapter to one of the available GND pins...and it should reload the firmware.

I've ordered an FTDI cable and will give it a try.  I'll get back to you guys to let you know if it worked.

 

[Rigel]

You can also find a slightly different procedure as suggested by DIYDrones here:  http://todigi.blogspot.com/2010/05/xbee-obituaries-xbee-returns-fro...

 

 

[Rigel]

Ok, so I finally got around to unbricking my Xbees attached to their adapters by using an FTDI cable.  Here's how you do it:

 

1-  Connect your FTDI and Xbee with adapter.

2-  Start X-CTU

3-  Under the first tabe "PC Settings", make sure to set your Baud rate to 9600

4-  Select the "Modem Configuration" Tab and check "Always Update Firmware"

5-  Select your modem type under "Modem":  See bottom of manual for modem types: http://code.google.com/p/ardupilot-mega/wiki/Wireless

6-  Using a jumper wire, connect the "RESET" pin under the adapter to any of the GND pins like this:

Picture shows me touching one of the soldered GND pins but it's much easier to shove your jumper in one of the unused GND holes.

7- In X-CTU click "Write".  You may need a second pair of hands to help.

8- When you get the "Action Needed" popup, simply pull out your jumper and X-CTU should start programing your modem.

9-  You can now quickly test to see if your Xbee is recognized by clicking on the "Test / Query" button under the "PC Settings tab"

10-  If all is well, under the "Modem Configuration" tab reset your Modem ID to one that matches your other Xbee module:

11-  Also reset your Baud rate to whatever you've selected your communication speed to be.  Default for APM is 57600:

12-  Click "Write" again and you're done!

 

You can test again to see if everything is working properly by cliking the "Test / Query" button.  Just make sure to change the baud rate under the "PC Settings" tab to whatever you've just programed into your Xbee.

 

Your Xbee should now be able to communicate with APM Planner.  You can also test communication between both your Xbees by doing a loopback as described in the manual here:  http://code.google.com/p/ardupilot-mega/wiki/Wireless

You'll need to power your Xbee with the proper voltage, and it basically looks like this:

 

Using X-CTU, connect your ground side Xbee and click "Start" under the Range Test tab. 

If everything is working well, you'll get results similar to this.

I hope this helps those of you, like myself, that still have a lot to learn about soldering!  Have fun.

[Colin Bouriquet]

When you tick the RSSI check box in the loopback test, is the number supposed to change to reflect the quality of the signal ? Mine always stays at -82 no matter what... is something wrong ? Thanks.

[Rigel]

It probably won't change if you are stationary.  Try moving one of your Xbees about 100ft away from the other and you should see changes. 

[Colin Bouriquet]

Thanks Rigel... after some investigation i found out that there is a -80dB RSSI threshold for the Xbee pro 900 that's why didn't see the number moving.