Wire worked by not wireless

[Christopher4187]

I forgot to mention, it is possible that your software may have an issue with timing. When I use a wireless link, I typically give a little more time for the transmit and receive signals....maybe an extra 10 to 20ms.

[mankan]

Chris,

Thank you very much for the reply. This is my first project with the PIC. Is there any other issue apart from time-to-transmit?

Do you see anything wrong with my code? It worked fine with the wires.I have even grounded the Rx DataIn pin to overcome the noise.

I am using laipac 434 series of Tx/Rx.

Thanks,
Mankan

[Christopher4187]

I have never used those but I have used Linx Technologies LR series modules. I found that without a 10K pullup resistor (to +5V) on the RX side, they would not work at all. The TX side did not need anything. Are you making only a transmitter and receiver or are you making two transceivers. Don't forget that you cannot have to transmitters transmitting at the same time. With the Linx modules, if you don't pull down the PDN line, the transmit port will always be open making it impossible to send data. Of course, if only using one TX and one RX, this is not a problem. The other thing you may look at is interference in the surrounding area. Let me know if you still have problems.

[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