Help with 18b20 Stuck with busy bit

Hello there, im kind new with pics but i have some knowledge about basic schematics and programming.
- I use pic6F88
- Oscilator 20Mhz
-And for testing reasons because i dont have an lcd screen i use TX/RX pseudo-RS232

I have started a project that i need to read 18b20's temp and do something else... but i stuck in busy bit 1 month now, and can't find any solution :'(.

Im kinda desperate because i dont know what else to check....

Here is my code :

include "modedefs.bas"
'---------------------------------------------------------------
' DEFINES
'---------------------------------------------------------------
TRISA=%00000010
TRISB=%00000100
CMCON=0
ANSEL=0
ADCON0=0
DEFINE OSC 20
'---------------------------------------------------------------
' Variables
'---------------------------------------------------------------

present var bit
count_remain var byte
count_per_c var byte
sign1 var byte
tempout var byte
temp var byte
t05 var byte
t05out var byte
tempb20 VAR WORD
DQ VAR PORTA.1
RX VAR PORTB.2
TX VAR PORTB.5

'--------------------------------------------------------------
' Initialisation
'--------------------------------------------------------------
CLEAR
serout tx,n9600,["TEST OK",13,10]
pause 1500
'-------------------------------------------------------------
' Main prog
'-------------------------------------------------------------
main:
while 1
gosub sensor_ch1
IF present=1 then
gosub mainloop1
tempout=temp
t05out=t05
else
tempout=99
t05out=9
endif
Serout2 tx,16468,["T=",dec2 tempout,",",t05out,"C",13,10]
pause 250

wend
'================================================= =
' Subroutines
'================================================= =

'------------------------------------------------------------------------------------------
' Presence
'------------------------------------------------------------------------------------------

sensor_ch1:
Low DQ 'Set the data pin low to initialize
PauseUs 500 'Wait for more than 480us
TRISA.1=1 'Release the data pin (set to input for high)
PauseUs 100 'Wait for more than 60us
IF DQ=1 Then 'Is there a DS1820 detected Present=1
present=0 'If not, then clear DS_VALID flag Presebt=0
Else
present=1
EndIF
Return 'And return with DS_Valid holding 0
'---------------------------------------------------------------------------------------------------
' Read 18B20 Sensor
'---------------------------------------------------------------------------------------------------
mainloop1:
TRISA.1=0 'read temp ch0 connect it to RA.1
OWOut DQ, 1, [$CC, $44] 'Start temperature conversion
waitloop1:
pauseus 200
OWOut DQ, 1, [$CC, $BE] 'Read the temperature
TRISA.1=1
OWIn DQ, 0, [tempb20.LOWBYTE, tempb20.HIGHBYTE, Skip 4, count_remain, count_per_c]
IF tempb20.15=1 Then
sign1=1
if tempb20.3=1 and tempb20.2=0 and tempb20.1=0 and tempb20.0=0 then
t05="5"
else
t05="0"
endif
tempb20=tempb20 >> 4
tempb20=tempb20.lowbyte ^ 255'Reverse the bits of the lowbyte of TEMP because negative
temp=tempb20.lowbyte
Else
sign1=0
if tempb20.3=1 then t05="5"
if tempb20.3=0 then t05="0"
tempb20=tempb20 >> 4
temp=tempb20.lowbyte
EndIF
Return
eND

you might take a look at this example... (located in the wiki section under projects/temperature)

http://www.picbasic.co.uk/forum/cont...r-nine-of-them

you can also search on "ds18b20" for other examples.
I would suggest you go through your code and add lots of comments to help you trouble shoot and for others to follow what you are trying to do.

Ty Heckler for the reply, but the link that you gave me my friend doesn't work. Stuck in loading... I deleted comments for posting on site i have done them properly :P :P

My problem is the presence pulse, i can't understand how it works even i have read the datasheet hundrend of times.

I do low for initialise, i do get a low and going for the converting procedure. But i never get the busy bit back, even i did it with 2 diffrent ways.

I suspect that the problem is the presence pulse but i dont know how to check it and that's why i came with a post (i also have read a couple of other threads but still no luck) .

Take a look here, for a verry good example : http://www.rentron.com/PicBasic/one-wire3.htm

I think i found out the problem.... I haven't disabled the A/D inputs nor the Comparators and OPTION_REG . I'll try it out when i have time and ill let you know :) !!!