Let's Make Robots!

Help me connect Xbee to Picaxe!

OK, so I’m going to make a remote control to my next robot. I want to connect a picaxe 28x1 to a Xbee and I have ben trying to find
some good examples but with limited success.

As the Picaxe operates at 5V, whilst the Xbee operates at 3.3V I understand that the signal from the picaxe has to be regulated. (not just the input voltage to drive the device).
Of Cause I could run both the picaxe and the Xbee at 3.3V, but that would just screw with everything else I'm gonna connect to it.


I have Ben looking around for adapter-kits that would take care of the signal regulation, but if it would be possible to make a simple one (PCB with on-board Picaxe) , that would be preferred.
Will this circuit fry my Xbee?? This is probably all wrong so I need your input! What am I missing?? I'm a noob so go hard on me!



Will this simple voltage divider do the trick?


Also I have come to understand that you will have to program the xbee module to run at a lower speed to be able to communicate with a Picaxe.
The Xbees default Baud Rate parameter is 3 (9600 bps).
So it seems that I will have to buy at least one Axe210 PICAXE Connect Board and use the Xbee wizard in the Picaxe programming editor to lower the Baud Rate to 2400, and set the Brodcast channel,network group, destination nickname etc...

Also any recommendations of adapter boards or links to information is welcome.

(powerpoint version for windows of the connection at: http://dl.dropbox.com/u/8788764/bigbot/xbee%20ppt.pptx)

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Thank you all for your kind and helpful answers! I decided to buy a XBee adapter. And then I got another problem after this one witch LMR-members where able to solve! Hope this forum post will help others who want to connect an XBee to picaxe.

 

 

I have had an Xbee working successfully with a picaxe for debugging but you cannot use then for program uploading because the picaxe bootloader requires a special command that the Xbees can't emulate :(

Below is the interface I used. This give the Xbee a 3.2V supply, translates voltages and very importantly for picaxe, it inverts the signals.

 

You can always use a level shifting interface board for the XBee like this one.

I do believe that the xbee is 5 tollerent so you shouldn't have any issue with level conversion. In fact, I've run an xbee and arduino without any divider without issue. In fact here is from there page at digi:Serial Data Interface: 3.3V CMOS UART (5V tolerant inputs)

http://www.digi.com/products/wireless/zigbee-mesh/xbee-digimesh-900.jsp

Also, doesn't the 28x1 go up to 9600? You should be able to run it no problem.

If your Xbee's have survived 5V then I think it was as much luck on your part (flat batteries perhaps) rather than any tolerance to 5V. Unless your manual states they are 5V tolerant then I wouldn't risk it.

well, thats why I posted this in my response....

 from their page at digi:Serial Data Interface: 3.3V CMOS UART (5V tolerant inputs)

HI,

I've never worked with Xbee, but I know about the different voltages ;)

The voltage divider on out7 looks OK, 3.333 volts going to the Xbee, which is perfect.

But I thing there is a problem with In7: as Xbee works on 3.3V, the signal it sends out wil not be strong enough for the picaxe µC. This, I don't know for a fact but I think the the signals won't be good...