Carrier Signal Required for Encoded RF Transmissions?

I have these [encoder/decoder components(CIP-8) currently hooked up via these [transmission components.

I am planning to use a PIC or BS2 to send/receive serial data over one of the I/O wires. Do I have to use a carrier signal in addition to the serial data before sending it to the encoder? Or can I just send the serial data directly into the encoder from the chip?

Thanks!](Reviews of Software & Service Providers | SERP)](Reviews of Software & Service Providers | SERP)

Your question seems to be: can one feed data into the decoder that was not transmitted via a carrier on RF and then demodulated by a receiver. That is, a non-RF situation such as a wire + GND carrying serial data.

I believe that the decoder chip accepts serial data. That data can be produced by most any device, including a microprocessor, an encoder chip from the same product line, etc. The use of a transmitter/receiver RF link is kind of "transparent’ to this, except that it is noisy and error prone.

not knowing much about your application, my first thought was “why?”. I’d just use the serial (UART, USART, async) capability of the PIC or what ever.

No carrier is required. The RF link is ASK/OOP, which means the data is transmitted by turning the carrier on and off as opposed to using the data to modulate the carrier (FSK, FM, etc.)

The encoder/decoder you referenced are designed to transmit switch closure state over the RF link and have it reflected on the other end. I believe that they are specially programmed PIC devices that handle the data encoding. They do their job very well. Using a PIC to provide the open/close state to the encoder is the limit that you can do with these chips. If you are talking transmitting serial data over the RF link, that is a different matter all together. There are many threads on this forum and others that describe the required techniques.

The approach you take depends upon what you are trying to do.

Philba:
I’d just use the serial (UART, USART, async) capability of the PIC or what ever.

I do plan on using the UART of the PIC for the serial input/output. The RF components, and en/decoder are just for the RF transmission. Maybe I am incorrect, but wouldn’t you have to feed the output of the UART into the RF encoder and the output of the RF decoder into the receiving component’s UART?

Actually, I was planning on using a software serial implementation since the chip I have does not have a UART.

riden:
No carrier is required. The RF link is ASK/OOP, which means the data is transmitted by turning the carrier on and off as opposed to using the data to modulate the carrier (FSK, FM, etc.)

Ok, that makes sense. Thanks for the help.

riden:
The encoder/decoder you referenced are designed to transmit switch closure state over the RF link and have it reflected on the other end. I believe that they are specially programmed PIC devices that handle the data encoding. They do their job very well.

I have gotten them to do that and it was very straight forward. My questions arose when I started trying to send/receive serial data through the components via software uart.

riden:
Using a PIC to provide the open/close state to the encoder is the limit that you can do with these chips. If you are talking transmitting serial data over the RF link, that is a different matter all together. There are many threads on this forum and others that describe the required techniques.

I attempted to implement a software uart (as the chip I am using, 16F684 does not have a hardware one), but without much success so far. I read [this tutorial but I fear I lost some important logic in the changes I made to make it work with my compiler (PICC-Lite). Some additional online research suggested a sw_uart c library, but I was not able to find it available for download.

I think my searching abilities leave something to be desired (as I did try to search before posting!), could you please point me to any pertinent posts for transmitting the data via software uart?

Thanks - I appreciate the help!](http://www.sparkfun.com/commerce/present.php?p=The%20Serial%20Biggie%20Page1)