Wire worked by not wireless

[dhouston]

The Laipac modules (also widely available under other names) use ASK and the suprerregenerative receiver has AGC/ATC so the output line will have continuous noise in the absence of a signal. I would not try to use serial in and out but would use some type of preamble that will serve to tell the receiver that a message is coming and also allow it to set its AGC/ATC. I use the NEC IR protocol and have never had much of a problem sending/receiving. However, it may or may not be the best choice depending on the type of data you need to transmit. The length of messages casn be a determining factor.

I don't recall what Bruce Reynolds uses in his examples but he does have some examples using these modules on his web site.

[mankan]

I am doing RF Tx/Rx not an IR. Is there anything special to be taken care of something?

Thanks,
Mankan

[dhouston]

It doesn't matter whether it's IR or RF. A protocol is a protocol and the priciples are the same. The only difference is that on the receiving end most IR receivers are active low while RF receivers are active high. X-10 has used the NEC IR protocol for their RF remotes for about 20 years, now.

But, even if you want to use manchester coding, you will still need a preamble to alert the receiver.

There is one other key difference with IR. IR receivers do not output continuous noise in the absence of a signal, so a preamble is not always necessary. Nevertheless, most protocols still use one.

[mankan]

Hello Chris,

I followed your suggestion and I added a pull-up resistor but nothing improved. Any other suggestions.

I am planning to look at the txmitted code pattern.

-Mankan

[Christopher4187]

If you can't find someone who has used these modules or get tech support, there is an easier option. Linx Technologies has a transmitter and receiver pair that can cost as low as about $16 (depending upon quantites and where you get them) in the SMT version. Bruce at Rentron.com sells the pinned versions and while I have never used them before, I'm sure they work fine. I have made many different designs with these modules and Linx claims 3000+ feet but I have never seen that but it's probably due to my inefficient layout of the PCB. If your power supply is clean and the correct voltage, you don't need any external components except for the 10K pullup on the receive line. The data in is the data out. If you need a short range, something like 500 feet, you can use the HETH antenna for your frequency which sells for .67 cents. They are easy to use and relatively cheap. One thing I need to mention, if you don't purchase an evaluation kit, they won't give you tech support. However, if you do want one, I have one here that I will sell for a cheap price. No worries though, if you don't want to purchase one, I will still help you if you need it.

[mankan]

Hello,

Is the other way to test a RF link? Like using PulsIn and wait for the RF pulse on a particular pin.

Just to make sure that link works.

Thanks,
Mankan

[Squibcakes]

Gidday mate,

You can make this work! Say it out loud 10 times OK!

When the TX is not sending data the RX will be picking up noise, the PIC will see this noise as data, so you need to do a few things.

1. Encode the data (which you have already done) and decode at RX.
2. Add a preamble before you send your data strings,

eg send about 10 bytes of data (eg "RFDATAREADY") and on your receiver have it waiting for the text "READY"

Then start sending your data.

I found that it was useful to use an oscilliscope so you could see the data at TX and RX chips, and see the noise when your not transmitting.

Good luck
J