Decoding DMX with picbasic pro

[fred.pacc]

hello,

I have studied the posts concerning dmx with picbasic, I want to dimming a led on portC.5 on a 18F452. I try this basic code but unfortunately it doesn't run.

the dmx is converted by a driver SN75176 connected on pin 26 (RC.7/RX/DT). Please is someone can look my code for help me.

sorry for my bad english i'm french.....
greating

'****************************************************************
'*  Name    : UNTITLED.BAS                                      *
'*  Author  : [select VIEW...EDITOR OPTIONS]                    *
'*  Notice  : Copyright (c) 2006 [select VIEW...EDITOR OPTIONS] *
'*          : All Rights Reserved                               *
'*  Date    : 26/01/2006                                        *
'*  Version : 1.0                                               *
'*  Notes   :                                                   *
'*          :                                                   *
'****************************************************************
DEFINE OSC 16             ' for pic 18f452  
DEFINE HSER_BAUD 250000    
DEFINE HSER_CLROERR 1
ASM
        ERRORLEVEL -306, -302
ENDASM

' Variables diverves 
 
      counter        VAR word                ' Variable de travail WORD
      idleflag       VAR WORD          
      dummy          VAR WORD  
      RCIF           VAR byte
      startcode      VAR WORD
      aminus         VAR WORD
      adresse_grada  VAR WORD
      x              VAR WORD
      newlevel1     VAR WORD
   
adresse_grada = 20
    
'This next routine is called on a gosub from my main housekeeping loop:

checkdmx:

counter = 1 'just a dummy variable
pulsin portc.7,0,counter 'here I'm looking for the break signal

if counter = 0 then
    idleflag = 1 'either no dmx, or break was too long to count
    'return
endif


if counter < 40 then checkdmx 'watching for 'break
'if you get here, an active low pulse was detected, but it was too short.
'probably just part of the datastream. So go back and look again.

'otherwise, a valid break was found and it's time to read the start code

dummy = RCREG 'clear out any garbage which may be in the USART
dummy = RCREG
SPBRG = 0 
TXSTA.2 = 0 'brgh = 0
TXSTA.4 = 0
RCSTA.7 = 1 
RCSTA.6 = 0 'setting 8 bit receive mode, no parity, etc 
RCSTA.4 = 0 'check the datasheet to see what all these bits do
RCSTA.4 = 1 'now, the USART is on and ready to receive

while RCIF = 0:wend 'hover here after break, before start code

startcode = RCREG 'This is the first byte received after the break

if startcode <> 0 then checkdmx 'do your own stuff here on a non-zero code

aminus = adresse_grada - 1 'address1 is my target address

for x = 1 to aminus 'set up a loop to count almost to the address
while RCIF = 0:WEND 'sit here until a byte is received
dummy = RCREG 'stash the byte somewhere unimportant
next x

newlevel1 = RCREG 'This is your target channel data
pwm portc.5, newlevel1 ,100  'i want dimming a LED on PORTC.5
RCSTA.7 = 0 'turn off the USART

goto checkdmx
return