text transmission using rf module and pic

[aswinishere007]

Hello, I have to do a mini project on this year...i searched a lot...and finally decided to choose wireless text transfer system....i want to send a text from pc via serail port and low cost rf module and receive it using a pic 16f77a and display the text in an lcd.....i want to know what is ur opinions about this project?is it possible?i seen lots of circuits which used to transfer 4 bit,bit data using rf modules...but no such sites tell nothing about text transfer...ie to transmit data such as a,b,c,d,e.....z ...if anyone have any prior experience in it,pls give me assistance...it is very important..suggestions are welcomable

 

[betwixt]

I think you are confusing 4-bit with the circuit that interfaces with the LCD. Text data transmission is normally 7 or 8 bits of data.

It is possible to do but there are some problems. As long as you understand the problems it isn't difficult but you can't just feed data in at the transmiter and expect it to come out at the receiver. Although data will come out, you will almost certainly find it is corrupted and at the end of the transmission, the noise picked up by the receiver will produce random characters. You have to adjust the data in software before sending it and then adjust it back at the receiver, this will minimize the risk of it becoming corrupted. If you need high reliability, you should also consider a method of asking the PC to resend data that wasn't received properly.

I suggest you research "Manchester encoding" which is probably the most commonly used transmission method and also ASCII coding and how 4-bit LCD interfaces work.

Brian.

 

[zeeekay]

Since you are doing it as a mini-project... why don't you buy an off the shelf RF transmitter/receiver pair. Any transparent module will work for you. I have been using HopeRF HM-TR modules for a while for such applications. They can receive data directly from serial port. The other end (transceiver) will hand-over data to microcontroller.. You can easily display received data on LCD. I suggest you to do it in steps:

1. Try driving LCD along using ur PIC MCU
2. Second, connect your circuit with computers serial port via a wired connection.
3. Replace wired connection with a wireless RF module.