' Name        : LTCX.pbp
' Compiler    : PICBASIC PRO Compiler 2.6
' Assembler   : PM or MPASM
' Target PIC  : 40-pin 16F877A, 18F452 or similar
' Hardware    : LAB-X1 Experimenter Board
' Oscillator  : 4MHz external crystal
' Keywords    : SHIFTIN, SHIFTOUT, LCDOUT
' Description : PICBASIC PRO program to read LTC1298 ADC.
'

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

' 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

Include "modedefs.bas"

' Alias pins
CS Var PORTC.5   ' Chip select
CK Var PORTC.3   ' Clock
DI Var PORTA.2   ' Data in
D0 Var PORTC.1   ' Data out

' Allocate variables
addr   Var Byte  ' Channel address / mode
x      Var Word
y      Var Word
z      Var Word
result Var Word

   High CS       ' Chip select inactive
   ADCON1 = 7    ' Set PORTA, PORTE to digital
   Low PORTE.2   ' LCD R/W line low (W)
   Pause 100     ' Wait for LCD to start

   Goto mainloop ' Skip subroutines

' Subroutine to read a/d convertor
getad:
   CS = 0        ' Chip select active
   
   ' Send address / mode - Start bit, 3 bit addr, null bit]
   Shiftout DI, CK, MSBFIRST, [1\1, addr\3, 0\1]
   Shiftin D0, CK, MSBPRE, [result\12]  ' Get 12-bit result
   CS = 1        ' Chip select inactive
   Return

' Subroutine to get x value (channel 0)
getx:
   addr = $05    ' Single ended, channel 0, MSBF high
   Gosub getad
   x = result
   Return

' Subroutine to get y value (channel 1)
gety:
   addr = $07    ' Single ended, channel 1, MSBF high
   Gosub getad
   y = result
   Return

' Subroutine to get z value (differential)
getz:
   addr = $01    ' Differential (ch0 = +, ch1 = -), MSBF high
   Gosub getad
   z = result
   Return

mainloop:
   Gosub getx    ' Get x value
   Gosub gety    ' Get y value
   Gosub getz    ' Get z value

   Lcdout $fe, 1, "x=", #x, " y=", #y, " z=", #z ' Send values to LCD
   Pause 100       ' Do it about 10 times a second
   Goto  mainloop  ' Do it forever

   End