Thermo 7 segments - little problem

[fratello]

I made this schematic; I use this code. Works fine, but.... I don't know how to display "minus sign" for negative temperatures. I try differents variants, but without results...Any advice it's wellcome ! Thanks in advance !

' *************************************************************
' * For use with EXPERIMENTING WITH THE PICBASIC PRO COMPILER *
' *			                                            *
' *  This source code may be freely used within your own      *
' *  programs. However, if it is used for profitable reasons, *
' *        please give credit where credit is due.	        *
' *  And make a reference to myself or Rosetta Technologies   *
' *							                    *
' *			              Les. Johnson		        *
' *************************************************************
'
' Common Anode seven segment display multiplexer
' Displays the contents of the variable D_NUMBER on five common Anode displays
' using a TMR0 interrupt 
' ***********************************************************************
@ DEVICE pic16F648A, XT_OSC, WDT_OFF, PWRT_OFF, BOD_OFF, MCLR_OFF, LVP_OFF, CPD_OFF       

  CMCON = 7                
  VRCON = 0
  INTCON = 0
Include "Modedefs.bas"

' ** Setup the Crystal Frequency, in mHz **

	Define 	OSC		4 		   	' Set Xtal Frequency

' ** Declare the Variables **
	LEDS		  	Var	Byte		      ' The amount of LEDs in the display
	O_C		    	Var	Byte		      ' Used by the interrupt for time sharing
	Counter		Var	Word		      ' General purpose counter
	Del		    	Var	Word		      ' General purpose delay loop variable
	D_Number		Var	Word		      ' The number to display on the LEDS
	DP		    	Var	Byte		      ' Position of the decimal point
	Disp_Patt		Var	Byte		      ' Pattern to output to PortC
	Num		    	Var	Byte[5]	      ' Array to hold each digits value
	Digit0		Var	PortA.0		' Controls the first DIGIT on the LED
	Digit1		Var	PortA.1		' Controls the second DIGIT on the LED
	Digit2		Var	PortA.2		' Controls the third DIGIT on the LED
	Digit3		Var	PortA.3		' Controls the fourth DIGIT on the LED
      
	temperature       var   word
	TempC             Var   word
	Temp	            Var   byte
      Float             Var   word
	V		      Var   word		  
	Twist             Var   bit
	Dummy             Var   byte
      Sign              var   byte
	busy              var   bit
	DS18B20_12bit 	CON %01111111           ' 750ms,   0.0625°C  
	DQ			var PortA.4


' ** Declare the bits and flags of the various registers **

	T0IE		Var	INTCON.5	      	' Timer0 Overflow Interrupt Enable
	T0IF		Var	INTCON.2	      	' Timer0 Overflow Interrupt Flag
	GIE		Var	INTCON.7	        	' Global Interrupt Enable
	PS0		Var	OPTION_REG.0	    	' Prescaler division bit-0
	PS1		Var	OPTION_REG.1	    	' Prescaler division bit-1
	PS2		Var	OPTION_REG.2	    	' Prescaler division bit-2
	PSA		Var	OPTION_REG.3	   	' Prescaler Assignment (1= assigned to WDT)
                              			'    (0= assigned to oscillator)
	T0CS		Var	OPTION_REG.5	  	' Timer0 Clock Source Select (0=Internal clock) 
                             				'    (1=External PORTA.4)
                              
                              
' Set TMR0 to interrupt
	GIE=0				      		' Turn off global interrupts
	While GIE=1:GIE=0:Wend				' Make sure they are off
	PSA=0							' Assign the prescaler to external oscillator
	PS0=0							' Set the prescaler
	PS1=1							' to increment TMR0
	PS2=0							' every 64th instruction cycle
	T0CS=0						' Assign TMR0 clock to internal source
	TMR0=0						' Clear TMR0 initially
	T0IE=1						' Enable TMR0 overflow interrupt
	GIE=1							' Enable global interrupts

On Interrupt Goto Mult_Int				' Point to the interrupt handler

	TrisB=0						' Make PortB outputs
	TrisA.0=0:TrisA.1=0:TrisA.2=0			' Make only the specific bits of PortA outputs					
	TrisA.3=0:TrisA.4=1
	PortA=0:PortB=0			      	' Clear PortB and PortA
	O_C=0							' Clear the time share variable 




OWOut DQ, 1, [$CC, $4E, 0, 0, DS18B20_12bit]
 Output DQ              		' Make Pin Output
 DQ=0						' OneWire line Low
 PauseUs 480                    	' Keep down for 480 µS  
 Input DQ                       	' Make Pin Input
 PauseUs 70                     	' Wait 70 µS


W1: 
    OWIN DQ,4,[busy]            	' Check for still busy converting
    IF busy = 0 THEN W1         	' Still busy?  then loop

' ** THE MAIN PROGRAM STARTS HERE **
	
Main:	
OWOut DQ, 1, [$CC, $44] 
OWOut DQ, 1, [$CC, $BE]
OWIn DQ, 2, [temperature.byte0, temperature.byte1]         
If Temperature.15 then       
  Temperature= ~Temperature +1
  Twist = 1
  Sign  = 1
Endif
 
Dummy = 625 * Temperature
TempC = DIV32 10 
TempC = (Temperature & $7FF) >> 4
Float = ((Temperature.Lowbyte & $0F ) * 25 )>>2
Temperature = TempC*100 + Float

If Twist then
  V= 10000 - Temperature            		' 25 C=12500  0 C=10000  -10 C=9000 
  Twist = 0
else
  V= 10000 + Temperature
EndIf

If V >= 10000 then                     		' Above 0 C.      
  Temperature=V-10000
  sign = " "                   
else                                   
  Temperature=10000-V                   		' Below 0 C. 
  sign= "-"
EndIf
	D_Number=Temperature/10			      ' Place the value to display into D_NUMBER
	DP=0					            ' Disable the decimal point
	Gosub Display				      ' Display the value
	 For Del=0 to 100			      	' Pause 10ms
	 Pauseus 100				      ' using smaller delays
	 Next

Inf:	
Goto Main				              	' Do it forever

' Build up the seperate digits of variable D_NUMBER
' into the array NUM. Each LED is assigned to each array variable.
' LED-0 (right) displays the value of NUM[0]
' LED-1 (middle) displays the value of NUM[1]
' LED-2 (lef) displays the value of NUM[2]
' The decimal point is placed by loading the variable DP
' with the LED of choice to place the point (0..5). where 1 is the farthest right LED
' and 0 disables the decimal point.
Display:
	For LEDS=3 to 0 step -1 				' Loop for 4 digits (0-9999)
	Disable							' Disable the interrupt while we calculate
	Num[LEDS]=D_Number dig LEDS 				' Extract the seperate digits into the array
	If D_Number<10 and LEDS=1 then Num[LEDS]=10	' Zero Suppression for the second digit
	If D_Number<100 and LEDS=2 then Num[LEDS]=10	' Zero Suppression for the Third digit
	If D_Number<1000 and LEDS=3 then Num[LEDS]=10	' Zero Suppression for the Forth digit
	Enable							' Re-enable the interrupt
	Next	



' INTERRUPT HANDLER 
' Multiplexes the 4-digits
' 
        Disable         			' Disable all interupts during the interrupt handler
Mult_Int: 
	Lookup Num[O_C],[192,249,164,176,153,146,131,248,128,152,255],Disp_Patt ' Decode the segments for the LED

' Process the first display (farthest right)
	If O_C=0 then				' If it is our turn then
	Digit3=0					' Turn OFF the fourth LED
	PortB=Disp_Patt				' Place the digit pattern on portC
	If DP=1 then PortB.7=0			' Check the value of DP and Turn ON the decimal point
	Digit0=1					' Turn ON the first LED
	Endif
' Process the second display
	If O_C=1 then				' If it is our turn then
	Digit0=0					' Turn OFF the first LED
	PortB=Disp_Patt				' Place the digit pattern on portC
	If DP=2 then PortB.7=0			' Check the value of DP and Turn ON the decimal point
	Digit1=1					' Turn ON the second LED
	Endif
' Process the third display
	If O_C=2 then				' If it is our turn then
	Digit1=0					' Turn OFF the second LED
	PortB=Disp_Patt				' Place the digit pattern on portC
	If DP=3 then PortB.7=0			' Check the value of DP and Turn ON the decimal point
	Digit2=1					' Turn ON the third LED
	Endif
' Process the fourth display
	If O_C=3 then				' If it is our turn then
	Digit2=0					' Turn OFF the third LED
	PortB=Disp_Patt				' Place the digit pattern on portC
	If DP=3 then PortB.7=0			' Check the value of DP and Turn ON the decimal point
	Digit3=1					' Turn ON the fourth LED
	Endif

	O_C=O_C+1					' Increment the time share counter
	If O_C>=4 then O_C=0			' If it reaches 4 or over then clear it

	T0IF=0    					' Reset TMR0 interrupt flag
        Resume					' Exit the interrupt
	Enable					' Allow more interrupts