' Name        : SERVOXU.pbp
' Compiler    : PICBASIC PRO Compiler 2.6
' Assembler   : MPASM
' Target PIC  : PIC18F4550 or similar type
' Hardware    : LAB-XUSB Experimenter Board
' Oscillator  : 20MHz external
' Keywords    : LCDOUT
' Description : PICBASIC PRO program to move RC servo 1 using buttons.
' Button 1 moves servo left, 2 centers servo, 3 moves servo right.
'

' Define LOADER_USED to allow use of the boot loader.
' This will not affect normal program operation.
Define LOADER_USED 1

' RESET_ORG can be set to move the BASIC program out of the way
' of any boot loader running from location 0, such as the
' Microchip USB boot loader
'Define RESET_ORG 800h

Define OSC 48      ' Core is running at 48MHz

' Define LCD pins
Define LCD_DREG  PORTD
Define LCD_DBIT  4
Define LCD_RSREG PORTE
Define LCD_RSBIT 0
Define LCD_EREG  PORTE
Define LCD_EBIT  1

pos    Var Word         ' Servo position
servo1 Var PORTA.2      ' Alias servo pin

   INTCON2.7 = 0        ' Enable PORTB pullups
   ADCON1 = 15          ' PORTA and PORTE to digital
   Low PORTE.2          ' LCD R/W low = write
   Low servo1           ' Servo output low
   PORTB = 0            ' PORTB lines low to read buttons
   TRISB = $fe          ' Enable first button row
   Pause 100            ' Wait for LCD to startup
   Gosub center         ' Center servo

' Main program loop
mainloop:
   ' Check any button pressed to move servo
   If PORTB.4 = 0 Then
       Gosub left
   Endif
   If PORTB.5 = 0 Then
      Gosub center
   Endif
   If PORTB.6 = 0 Then
      Gosub right
   Endif

   servo1 = 1           ' Start servo pulse
   Pauseus pos          ' Delay for servo pulse high time
   servo1 = 0           ' End servo pulse
   Pause 16             ' Servo update rate about 60Hz
   Goto mainloop        ' Do it all forever

' Move servo left
left:
   If pos < 2000 Then
      pos = pos + 1
      GoSub display     ' Display new position on LCD
   Endif
   Return

' Move servo right
right:
   If pos > 1000 Then
      pos = pos - 1
      GoSub display     ' Display new position on LCD
   Endif
   Return

' Center servo
center:
   pos = 1500
'  GoSub display        ' Display new position on LCD
'  Return

' Display position on LCD
display:
   Lcdout $fe, 1, "Position = ", #pos
   Return

   End