7segment.bas

82 sample programs written in BASCOM-8051 for 8051 developement

'--------------------------------------------------------------
'                 (c) 1997-2000 MCS Electronics
'--------------------------------------------------------------
'  file: 7SEGMENT.BAS
'  demo: how to use a 7 segment display mutiplexed using TIMER0
'  *TIMER1 is used for RS-232 baudrate generator
' The 7 segment displays are connected as following
' 7 SEGMENT    PORT PIN    value
' a             P1.0        1
' b             P1.1        2
' c             P1.2        4
' d             P1.3        8
' e             P1.4       16
' f             P1.5       32
' g             P1.7      128
'number 0 will be : a+b+c+d+e+f=1+2+4+8+16+32=63
'1 = b+c=2+4=6
'2=a+b+g+e+d=1+2+8+16+128=155
'3=a+b+c+d+g=1+2+4+8+128=143
'well the rest I leave up to you !
' The common can be common cathode or common anode
'This example uses common cathode so making one of the displays common 0V, will
'show the segments when the signals on P1 are positive
' Common 1     P3.0  MSB
' Common 2     P3.1
' Common 3     P3.2
' common 4     P3.3  LSB
'--------------------------------------------------------------

Dim Gt As Byte , L As Byte , Char As Byte , Disp As Byte , S As String * 5 , Z As String * 5

Config Timer0 = Timer , Gate = Internal , Mode = 2
'Timer0 = counter : timer0 operates as a counter
'Gate = Internal  : no external gate control
'Mode = 2         : 8-bit auto reload (default)

On Timer0 Timer_0_int
Load Timer0 , 100                       'when the timer reaches 100 an interrupt will occur
Enable Interrupts                       'enable the use of interrupts
Enable Timer0                           'enable the timer


Rem Setting Of Priority
Priority Set Timer0                     'highest priority
Start Timer0                            'start the timer


Do
  Gt = Gt + 1
  Wait 1
Loop                                                          'loop until users enters 1

End


Rem The Interrupt Handler For The Timer0 Interrupt
Timer_0_int:
  'we will display the valueof gt on the 7 segment displays
  P3 = P3 Or 15                                               'all displays off
  Disp = Disp + 1                                             'which display are we doing?
  If Disp > 4 Then Disp = 1

  S = Str(gt)                                                 'for example 123
  L = Len(s)                                                  'get the length of the string
  L = 4 - l
  Z = String(l , 48)
  Z = Z + S                                                   'add leading zeros


  mov r0,#{z}                                                 ; address of string
  mov a,{disp}                                                      ; value of disp
  dec a                                                       ; adjust
  add a,r0                                                    ; add to a
  mov r0,a                                                    ; address of character
  mov a,@r0                                                   ; get into acc
  subb a,#48                                                  ; strip ascii
  P1 = Lookup(acc , 7seg)
  If Disp = 1 Then
     Reset P3.0
  Elseif Disp = 2 Then
     Reset P3.1
  Elseif Disp = 3 Then
     Reset P3.2
  Elseif Disp = 4 Then
     Reset P3.3
  End If

Return


'here we store the values that will be assigned to P1 to show a number
'dont forget to add the other digit values!
7seg:
Data 63 , 6 , 155 , 143