DS1820 Negative Numbers and OffSet

[gadelhas]

Hi everyone once again;

I made a program to read a DS1820 showing positive and negative temperatures. I found a piece of code in this forum to handle that, and its workinf fine. Now i want to put an offset in the temperature that was readed, for instance if the sensor is at 18ºC and the OFFSETTEMP variable is 2, then the LCD shows 20ºC, if the OFFSETTEMP variable is -3 than the lcd shows 15ºC.

In the code you will see that i allready have a menu to change the OFFSETTEMP variable, however i don't know now how to interect with the temperature that i'm reading.

Attached is the Proteus file with the simulation of the code, the code, and the HEX file.

The "MENU" button its to enter the the menu, and the "+" and "-" button is to change the value of the OFFSETTEMP variable.

Can somebody give me a clue?

Here is the code:

'****************************************************************
'*  Name    : TESTE DS1820.BAS                                  *
'*  Author  : GADELHAS                                          *
'*  Notice  : Copyright (c)                                     *
'*          : All Rights Reserved                               *
'*  Date    : 23-04-2011                                        *
'*  Version : 1.0                                               *
'*  Notes   : BreadBoard + EASYPICV6                            *
'*          : PIC16F877A                                        *
'****************************************************************
DEFINE OSC 20
@ __config _HS_OSC & _WDT_OFF & _LVP_OFF & _CP_OFF & _BODEN_OFF & _PWRTE_OFF
'                               VARIABLES
' ====================================================================
 
 TEMPC        Var Word
 OFFSETTEMP   VAR BYTE
 SIGN         var bit
 FLAG         VAR BYTE
 
'                         PINOUT 1 = IN; 0 = OUT
' ====================================================================
          '76543210
 TRISA  = %00000000 
 TRISB  = %00000000 
 TRISC  = %10010000 
 TRISD  = %00001100 
 TRISE  = %00000000
 ADCON1 = 7
 
'                              ALIAS
' ====================================================================
 LED     VAR PORTB.7 
 BMENOS  var PORTD.2 
 BMAIS   var PORTD.3 
 BMENU   VAR PORTC.4 
 OUT     Var PORTC.2 
 DQ      VAR PORTE.2 
 
'                              DEFINITIONS
' ====================================================================
 
 DEFINE LCD_DREG PORTB      ' LCD Data bits on PORTB
 DEFINE LCD_DBIT 0          ' PORTB starting address
 DEFINE LCD_RSREG PORTB     ' LCD RS bit on PORTB
 DEFINE LCD_RSBIT 4         ' LCD RS bit address
 DEFINE LCD_EREG PORTB      ' LCD E bit on PORTB
 DEFINE LCD_EBIT 5          ' LCD E bit address
 DEFINE LCD_BITS 4          ' LCD in 4-bit mode
 DEFINE LCD_LINES 2         ' LCD has 2 rows
 DEFINE LCD_COMMANDUS 2000  ' Set command delay time in us
 DEFINE LCD_DATAUS 50       ' Set data delay time in us
 
'                             MAIN
' ==================================================================== 
PAUSE 100
 
INICIO:             '01234567890123456789
    Lcdout $fe, 1,  "    DS1820 Teste    "
    Lcdout $fe, $C0,"   HUGO  OLIVEIRA   " 
    Pause 1000 
 
MAIN:
        if Bmenu = 0 then
           Pause 200
           goto  MENU
        endif
 
        gosub SENSOR
 
        IF SIGN=1 THEN    
            Lcdout $fe, $C0, "Temp: -",DEC ABS (TEMPC/10), 223,"C         "
        else
            Lcdout $fe, $C0, "Temp: ",DEC ABS (TEMPC/10), 223,"C          "
        endif
Goto MAIN  
 
'                          BUTTON ROUTINE
' ====================================================================
MENU:
 flag=1
 while flag <> 0
     pause 100      
     if flag = 1 then
        Lcdout $fe, $1, "Menu 01-OffSet Temp."     
        if OFFSETTEMP.7 = 0 THEN
            Lcdout $fe, $C0,"OffSet: ", DEC abs(OFFSETTEMP) 
        ELSE
            Lcdout $fe, $C0,"OffSet: -", DEC abs(OFFSETTEMP)
        ENDIF
        gosub PLUSBUTTON 
        gosub MINUSBUTTON     
    endif
 
    if Bmenu =0 then
        pause 200
        if flag = 1 then
            flag =0
        else
            flag = flag + 1
        endif
    endif  
 wend
GOTO MAIN      
 
PLUSBUTTON:
    if Bmais = 0 then 
        pause 200   
        if flag = 1 then
            if OFFSETTEMP = 5 then
                OFFSETTEMP = 5
            else
                OFFSETTEMP=OFFSETTEMP + 1
            endif
        endif
    ENDIF
RETURN
MINUSBUTTON:
    if BMENOS = 0 then 
        pause 200   
        if flag = 1 then
            if OFFSETTEMP = 251 then
                OFFSETTEMP = 251
            else
                OFFSETTEMP=OFFSETTEMP - 1
            endif
        endif
    ENDIF
RETURN
'                          TEMPERATURE ROUTINE
' ====================================================================
SENSOR:
    owout DQ,1,[$CC, $44]
    Pause 200
    owout DQ,1,[$CC, $BE]
    OWIn  DQ, 2, [TempC.byte0, TempC.byte1]         
    sign = tempc.15
    TempC = ABS(TempC)
    TempC =(TempC>>1)*10 + (TempC.0 * 5)
return
END