Data Transmission project

[Eplanet]

hello
recently i make a simple project with FSK module for transmission data from PC to LCD.
if you look at this picture you understand me.
in this project i have a problem.
when i connecting enable pin (Receiver) for input data my LCD getting unwanted data from air and showing on my LCD very fast and i cant see correct data transmitted.

 

[Papabravo]

I think you have problem setting up the serial port parameters. Is the receiver supposed to produce data continuously? Are you correctly setting the cursor address on the LCD after displaying a certain amount of data?

 

[mister_e]

Maybe the receiver have an open collector output as well. Is there any protocol in use now?

Direct connection work (without RF modules)?

Any link/datasheet for those modules?

 

[Nigel Goodwin]

You can't just send plain RS232 over a radio link, you need Manchester coding or similar - you can buy (or create) micro-controllers to do this for you, or buy radio modules with them built-in.

Check here for examples

 

[Eplanet]

this is my program from receiver(PIC16F84A)

include"modedefs.bas"
lcdout 254,1
B0 var word
I VAR BYTE
H var byte
high portB.2

main:
for I=0 to 15
serin portB.0,T2400,B0
pause 100
lcdout B0
next I

lcdout 254,$C0

for H=0 to 15
serin portB.0,T2400,B0
pause 100
lcdout B0
next H

lcdout 254,1
lcdout 254,128

goto main


direct connection work

and you can see data sheet in this attachment
even disconnecting transmitter getting noise and show On LCD for example if i sending double A character "AA" you will see "A je S A 4 i "

 

[Nigel Goodwin]

Read my previous post!.

 

[Eplanet]

hi
i read your previous post but please tell me other method because i cant find RF600 in our market.
thanks

 

[Nigel Goodwin]

hi
i read your previous post but please tell me other method because i cant find RF600 in our market.
thanks

Use a PIC to do the Manchester conversion then, my tutorials include examples.

 

[mister_e]

If you can change the PC software, life is good. And YES communication protocol is important. Manchester is simple and work great.

In your current example, between each Byte, you don't want to wait 100mSec + LCDOUT execution time... Grandpa 16F84 don't have any USART buffer, SERIN is a bit-banging solution.

If you send 2 character, use 2 BYTEs on the PIC side.

For testing purpose only, you could try to send this string
UUUUU~AB
from your PC to your PIC. On the PIC side try the following

        B0 VAR BYTE
        B1 VAR BYTE
        LCDOUT $FE,1

START:
        serin portB.0,T2400,["~"],B0,B1
        lcdout $FE,1,B0,B1
        GOTO Start

You LCD should display AB

 

[Eplanet]

hi
thanks for replay but i dont want to send "~" before any data how about enable time in rf module you think enable pin should be always on?
i dont use PIC in transmitter rf module connecting to max232 directly and when dont send any data from pc data pin is 5v and when sending data increase to 2.70 - 2.60 - 2.90 ...
and how can calibrate send time with receive time fore eliminate any unwanted data ?
and please tell me how can i use manchester codes in pic programming?

 

[Eplanet]

hi friends
do you know how can i use with this data transmitter and receiver with PIC micro because this device have 4bit for data how can i use it ?
HM-EP is transmitter
HM-D is receiver
thanks

 

[corabeca]

can sent me your project

 

[Eplanet]

all post specially first post is totally my project
send serially data from PC to microcontroller board over LCD in 250meteres
thanks