Question about using Xbee to transmit waveforms

lzqxek11

Hi,

I am new to the XBee modules so I don't know how to start, what I want is that I want to transmit a piece of 38 KHz square waves using the XBee 1 series. What do I need to do to make it work? I checked the manual and start thinking that it won't work on XBees since its sample rate only at 1ms the maximum. I appreciate that if someone can help

Li

Franklin

Sorry to say you are right, it won't work at 38KHz.

bot7711

Can you explain more about the project or the function you are trying to solve using xbee, and how the 38 KHz fits in?

RobotWorkshop

You might be able to do this easily with a pair of these:

http://www.parallax.com/Store/Accessories/CommunicationRF/tabid/161/CategoryID/36/List/0/SortField/0/Level/a/ProductID/582/Default.aspx

The Xbee modules are cool but they may not be the best choice for what you want to do.

Robert

lzqxek11

bot7711 wrote: »

Can you explain more about the project or the function you are trying to solve using xbee, and how the 38 KHz fits in?

This is the thing, I am simulating a remote control deivce. I give order on a MCU and I want target device to receive the command wirelessly and generate 38KHz in some formats, which will be the IR signal. At first I thought XBee can do this without problem, but further reading leads that it wont, since im tight in time on my project, I guess best way doing this now is to make another MCU at receiving and make XBee to transmit serial data in order to make them talk to each other. Glad to hear more suggestions on this and wish me luck...

Daniel Harris

Hey lzqxek11,

I see. I've done a bit of work with the XBee modules while at Parallax. It sounds a bit like what you want is a "wireless wire" so that you can use only one MCU to generate the pulses and have them wireless transmitted to come out the other side. The XBee devices have "virtual wires" that let you do something similar, but Im not sure if you can have them switch at that high of speed (to generate the 38KHz carrier). Might be worth checking out though, but you have to do some additional configuration. See page 14 on the datasheet:

http://ftp1.digi.com/support/documentation/90000982_B.pdf


IMHO, the best way to go would be the 433 MHz transceivers that RobotWorkshop suggested:
http://www.parallax.com/Store/Accessories/CommunicationRF/tabid/161/CategoryID/36/List/0/SortField/0/Level/a/ProductID/582/Default.aspx

Those act like a "wireless wire" down to about 60 Hz, so the 38KHz shouldn't be a problem. I think the XBees would be more suited to sending configuration data from one MCU to another. For example, your master MCU would use the XBees to send your remote MCU some data telling it what IR code to send.

I hope this makes sense and helps .

micro_engineer

I've actually started working on something similar.

The most generic solution is to "sniff" the demodulated IR bits from an IR sensor, packetize them, then transmit to them to a receiving module to be restored via the required IR carrier frequency.

If you transmit the pure binary values contained the IR pulses observed, when they are packed into a formal protocol with error-checking, etc., you can have reliable data transmission, and it's applicable regardless of which wireless modules you use.

For example, I will be doing this:

IR signal -> IR sensor -> digital signal out -> MCU reads binary values and stores in bytes -> transmitted data message -> receiver gets data message -> Rx MCU remodulates using data via an IR chip or by itself.