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How do I link two microcontroller board via RF?

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binnyr

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Hi:
I am working on a project which uses two boards build around Atmel AT90S8515. At present I am using RS232 to communicate between these two boards. In a longer run I would require to use RF to link these two boards.

I know there are ready-to-use RF Tranceivers modules that I can buy and use directly. (e.g check h--p://wxw.linxtechnologies.com/). However this will shoot up the cost of the solution (after the US$ to INR conversion).

Is these any way I can achieve two way RF communication between these two boards by some simple trick and low cost components?

Thanks and Regards
Binny
 

Hi,

It depends on the distance you wanna reach and the data rate.

For short range and low data rate, you can use one uC output pint to command a transistor that turns on and off an oscillaotr at, say, 27MHz. That is, data is sent using OOK. It's up to you to implement the communication protocol.

Some "wireless" mice use this principle (logitech for instance).

There are also some low cost transmitters (see Micrel) and you have to look for the matching receiver.

Good luck

Humungus
 

I'm afraid the previous solution suggested will work ok. However, if communication distance exceeds 30cm then your only option will be an off the shelf radio module. A good option might be to design electromagnetic induction coil the same principle RFID tags work on but u'll get to realise that is too much trouble than its worth for your application cos u'll need at least a pair per MCU. And of course you can design your own radio module.

Good luck
 

Hi:
The distances i am looking for are in the range of 5-feet to 25-feet max(at present). I need to show this stuff as a POC (Proof of Concept) first before I can get the rugged RX/TX modules.

The baud rate also can be as low a 300bps.

Binny
 

For that distance the only other option will be IRDA link. This option will be cheaper but u'll face all the limitations of infrared link. If this is just a proof of concept then either you stick to the rs232 cable or get a proper radio link
 

Try RfSolutions, they have something to suit all budgets.

**broken link removed**
 

Dear all:

Thanks for all the suggestions and links. As stated earlier, I knew few of such sites which offer ready to use modules.

At the current stage of the project we will not be able to invest additional funds into it to make the POC with the RF link with readily available modules. Hence I was looking at all options to see if i can get a home cooked solution for the POC.

Also trying to import these stuff to India (when you don’t have their representatives in India) is a mess and will sometimes take more time.

Also online Credit Card order is not common in India when it comes to US payments.

Thanks
Binny
 

hi:

I have found someting that might be of intrest.

Its a 900 MHz tranceiver Reference Design kit article with Schematic/ PCB and documents. I am uploading the files in it:

Thanks and Regards
Binny
 

you can use CC1010 from chipcon
 

Transmitter is easy to build but receiver is harder, check out the Ming Modules
 

I don't want to sound negative but you will get to realise the research and development cost involved in building your tranciever from scratch in comparison to buying a ready made module will be relatively high. Unless of course you system will go into a full scale production eventually.
 

In addition to the design of a radio reciever. Use of a PLL to demodulate the signal if FM is a very good idea. It should reduce the component count significantly.

Good luck
 

In addition to the design of a radio reciever. Use of a PLL to demodulate the signal if FM is a very good idea. It should reduce the component count significantly.

Good luck
 

Since you data rate is very low, you can use those single chip transceivers. Please check the RFMD site.
 

I have experience with aurel component. It works very good but pcb must designed for RF aplication. Now you have aurel Transimiter that you don't need Extern Antenna. (100m).
 

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