Using two pairs of 433Mhz RF transmitter and Receiver problem

beramodk

Hello,

I'm having some trouble using two pairs of 27980 and 27981 RF transmitter and receiver modules.

When I hook up the transmitter to a power source, the receiver refuses to work. It only works when the transmitter is not hooked up to a power source.

I tried using different grounds for the transmitter and the receiver, but still no luck.

I'm using the freescale 6812 MC. I'm also using two pairs of this RF module because I need to send data back and forth, not one way.

Thanks for the help.

sylvie369

I think that in order to get useful help you're going to have to explain what you mean when you say that the receiver "works" and "refuses to work". How can you tell that the receiver is working when there's no power to the transmitter?

I would get one-way communications working first: just hook up one transmitter and one receiver, and get them to send and receive "1 2 3 4 5 6 7 8 9 10 11..." correctly. Are you getting that much to work?

If the problem comes up when you connect the second set (xcvr, rcvr), it seems that you might either have a power supply problem or you haven't coded the transmitted data correctly. If you're trying to send numbers from one unit to another, and also from the second unit back to the first, what's going to keep the first unit from receiving the numbers that it is sending instead of the ones the second unit is sending? In PBasic, you would put a unique code in front of the data to be sent, and use the "WAIT" function in SERIN to make sure you were receiving what you wanted to receive.

Post Edited (sylvie369) : 3/15/2008 11:13:33 AM GMT

beramodk

Yup, one way communication seems to work fine. I can see that the receiver is getting the correct data via a logic analyzer, and also output the data through the hyperterminal.

But the instant I hook up a transmitter(+5V and GND) near the receiver, the receiver data goes flat and doesn't seem to be able to collect any data.

The transmitter seems to work when both the xcvr and the rcvr are powered. It's only the Rx that goes flat. I'll try a different power source for each module, see if that helps any.

I'm pretty sure it's not my code because in my code I only have one way communication going on, yet the rcvr goes flat.

Thanks!

Bean

You must make the PDN pin on the transmitter LOW unless you are actively transmitting.

Bean.

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Leon

The transmitter is swamping the receiver. You might·be better off with a pair of transceivers, unless you set up some sort of protocol using Bean's suggestion.

Leon

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Post Edited (Leon) : 3/15/2008 2:50:43 PM GMT