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Topic: Wireless Suggestions (Read 1 time) previous topic - next topic

baum

I am interested in getting some wireless networks working for remotely controlling a robot w/ arduino from another arduino. Before you say Xbees, I have a mac and therefore can't config them.

I'm not really interested in extreme speed, but I want something that is cheap and easy to use. Any suggestions?

jgalak

Well, the vast majority of xBee configuration can be done with just a terminal program, so you can do almost everything you'd need on a Mac.  Only thing you need a PC for is to install the firmware onto the xBee in the 1st place, so if you can occasionally borrow a friend's PC, you should be ok.

That being said, here's a good summary of what's out there:

http://www.sparkfun.com/tutorials/128

baum

But Xbees will be overkill. Some of them have a freakin' 1 MILE range! I'm talking about ~20ft maximum. Do the General TX/RX (from sparkfun, cheap) work well if I use the virtual wire library?

Thanks!

Inopia

http://jeelabs.com/products/jeenode ?

tkbyd

Quote
Do the General TX/RX (from sparkfun, cheap)


If you mean the ones I think you mean, I don't think they can do what I think you think they can.

baum

This is the general TX/RX

The JeeNode uses this. Has anyone used it? Is it easy to use/reliable? It is smd, but the pin spacing is 2mm.

Thanks!

I've used these cheap RFs successfully.
RF Link Transmitter - 434MHz
http://proto-pic.co.uk/products/RF-Link-Transmitter-%252d-434MHz.html

The VirtualWire library makes programming it easy.
http://www.open.com.au/mikem/arduino/
Paul Allen

pluggy

The simple TXRX pairs work in line with what you pay for them, the virtualwire library is a software fudge to get around some of the issues with such primitive radio gear (in theory it should work with plain old serial).  Theres no error detection/correction as there there is with the bluetooth/wifi based kit, you write it yourself and live with the limitations.  
http://pluggy.is-a-geek.com/index.html

baum

But all I want to do is to send two integers- joystick y axis and joystick x axis. I should be able to send this with good enough speed and reliability as there is no noticeable errors or lag, right?

pluggy

I ran mine at 1000 bits / second to get the errors down. It worked but it wasn't fast. I used a checksum system for error detecting and ignored the stuff that didn't pass the checksum. Its one way only, so you need a pair to get a back channel.  I would have doubts about running a TX and RX together on similar frequencies in close proximity.  Its crude ASK modulation which is just on/off keying, the limitations of the simple AGC on the receiver is what the virtualwire library is supposed to help out with.

http://en.wikipedia.org/wiki/Amplitude-shift_keying

If one way and two values will do, its probably worth a stab for the low cost.

You're probably limited to checksums as error detection and there is no back channel to request a resend.

Just don't expect too much
http://pluggy.is-a-geek.com/index.html

baum

What about the Hope RFM12 or 22 modules? are those any good? There only $2 or $3 more expensive.

And I don't need 2-way: just sending 8 bit integers in 1 direction.

pluggy

No direct experience with them, but FSK has to be an improvement on ASK.  Its still just on/off keying though.
http://pluggy.is-a-geek.com/index.html

baum

What would you do for single direction, cheap RF?

pluggy

I used mine to avoid the need to run wires on a fixed installation, I abandoned wireless and just ran a cable in the end. I suspect the Hope kit using FSK would work better than the cheap ASK type, due to the AGC situation with FM modulation rather than AM, I reckon using the virtualwire library wouldn't give you any advantages over straight serial.   I'd certainly look at it.  FM/FSK is much less prone to interference than AM/ASK. 
http://pluggy.is-a-geek.com/index.html

baum

Or how about a nordic module such as this one? They are as expensive as xbee's, but you need minimal supporting hardware.

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