RF Transceiver – Recommendations?

AndyO · Post by **AndyO** » Tue Apr 14, 2009 12:31 pm

I’m looking to set up a wireless link between two Pics. Nothing very fancy – max range would be around 30m but it would need to go through a few walls. Data rate isn’t critical – 2400bps would be fine but higher would be a bonus.

My problem is that RF stuff is, and I fear always will be, a total black art to me. Therefore I’m looking for an off-the-shelf module which is as ready to go and as idiot-proof as possible. Something with an antenna at one end, power and data pins at the other, and magical bits in the middle which take care of encoding, transmitting, receiving, decoding, rejecting the nonsense, collision avoidance etc. would be ideal!

The XBee modules look interesting - http://www.digi.com/products/wireless/p ... module.jsp - but I wasn’t too sure how they would cope with going through walls or how straight forward they might be to use in practice. Anyone had any experience with these?

Anyone have a recommendation for anything else which might fit the bill?

Cheers,

Andy.

Toley · Post by **Toley** » Tue Apr 14, 2009 12:44 pm

Did you get a look at Linx modules :

http://www.linxtechnologies.com/

I use them and they work fine. But you have to implement a Squelch to avoid permanent noise to trigger the receiving PIC. You can use the internal comparator of the PIC to do that. Some Linx receiving modules already include a squelch.

ohararp · Post by **ohararp** » Wed Apr 15, 2009 12:41 am

XBEE is dead simple and will work right out of the box for this app. They default to 9600 so I would choose that for a baudrate

normnet · Post by **normnet** » Wed Apr 15, 2009 6:16 am

Does XBEE mesh network?

Relaying data from one to the next and if one drops out the others will
pick up the relaying.

Norm

AndyO · Post by **AndyO** » Wed Apr 15, 2009 12:04 pm

Thanks for the replies chaps. Think I'll try and get hold of a couple of XBee modules and have a go. The Linx modules look good and the datasheets are very clear but I fear that any tweaking needed to get them working would be beyond me at this stage!

Cheers.

Raistlin · Post by **Raistlin** » Fri Apr 17, 2009 10:19 am

Does XBEE mesh network?

yep they do

normnet · Post by **normnet** » Sat Apr 18, 2009 2:01 am

Does XBEE mesh network?

yep they do

Could you give specifics found such as distance of reliable transmitions and data rate?
Building construction and other possible factors?
If one drops out do the others pick up in real world setting?

Sorry if a little skeptical.

Norm

Raistlin · Post by **Raistlin** » Mon Apr 20, 2009 2:31 am

Take a look at digi's websire all the pertinent info is there.
the 868 and 900mhz versions have a rage of 10km or so with the right antenas

AndyO · Post by **AndyO** » Sat Apr 25, 2009 9:22 am

XBEE is dead simple and will work right out of the box for this app.

Wow, you weren't kidding. Just took delivery of the modules. Connected one to my laptop via USB and another to the serial port of my desktop via an RS232 driver. Fired up HyperTerminal the two were talking to each other straight away! I feel slightly cheated - surely it shouldn't be this easy!!

Looking forward to having a proper play with these and finding out what they can do (and getting them working with a PIC).

If anyone's looking for a UK supplier, I bought mine from here:

http://robosavvy.com/store/index.php/cP ... 50b0a923eb

They weren't the absolutely cheapest place but I used them because they do a nice breakout board which has an onboard 3.3v regulator and brings the pins of the XBee out to a breadboard-friendly 2.54mm spacing. They also do a USB board which I used to connect the XBee to my laptop.

AndyO · Post by **AndyO** » Sat May 09, 2009 12:23 am

Further to this, just went to the Robosavvy site and their prices have gone up by nearly 50%!!

Perhaps not such a good recommendation after all... Shame, as their service and delivery were excellent.

TonyR · Post by **TonyR** » Wed Oct 05, 2011 11:13 pm

In case anyone searches out this link with Xbee Swordfish problems, the Series 2 Xbees don't work straight out of the box as promoted. I tried. You need to download X-CTU and do some simple configs. and set device addressing. There are some blogs around with how to do that. They work great once thats done though.

Senacharim · Post by **Senacharim** » Thu Oct 06, 2011 2:47 pm

There are also "transparent" serial-to-bluetooth modules available which once configured pretend to be a 'wireless wire' and need no control from the PIC; just serial communication. I've used them myself and can vouch for their efficacy.

A quick search for "serial bluetooth" or "rs232 bluetooth" will net ya plenty of results.

Good luck! Please remember to reply later on this post with an anecdote as to your success/learning experience/spectacular failure so others can learn from your example.

yllis · Post by **yllis** » Thu Dec 08, 2011 8:34 am

Lo!
I have a similar situation as AndyO. And I'm a noob as well.
I'm building a radio controlled window shades, and I'd like the result not only work, but to look good as well. For this reason I'd like to use a ready remote controll, like this one:
http://www.beckermotors.co.uk/ec545-p-39.html

How easy is it to make that remote communicate with my project? Does it matter if I don't have the datasheet information of the remote? In other words, if I buy a rf reciever with the same frequency, how can make them work together or can I?

Thanks already..

Senacharim · Post by **Senacharim** » Thu Dec 08, 2011 2:23 pm

yllis wrote:Lo!
I have a similar situation as AndyO. And I'm a noob as well.
I'm building a radio controlled window shades, and I'd like the result not only work, but to look good as well. For this reason I'd like to use a ready remote controll, like this one:
http://www.beckermotors.co.uk/ec545-p-39.html

How easy is it to make that remote communicate with my project? Does it matter if I don't have the datasheet information of the remote? In other words, if I buy a rf reciever with the same frequency, how can make them work together or can I?

Thanks already..

I've worked with similar devices. If it works like the ones I've used, then you'll have paired microchips which require that a series of pins be set the same (in order to put them on the same "channel") after which they function almost like a wireless TTL signal--with some small delay.

My advice--get the spec sheet, read the spec sheet, read the spec sheet again.

yllis · Post by **yllis** » Fri Dec 09, 2011 9:25 am

Lo!
Thanks for the reply..
How ever the problem is that if I buy a commercial, good looking remote, then I won't get the data sheet for it.. I could maybe ask the manufacturer for it, but I doubt if they are willing to share that data.

So is there a way to find out how to make them communicate?