' Name        : VMETERX.pbp
' Compiler    : PICBASIC PRO Compiler 2.6
' Assembler   : PM or MPASM
' Target PIC  : 40-pin 16F877 or similar
' Hardware    : LAB-X1 Experimenter Board
' Oscillator  : 4MHz external
' Keywords    : ADCIN, LCDOUT
' Description : PICBASIC PRO program to measure voltage (0-5VDC)
' and display on LCD with 2 decimal places.
'

' This program uses the */ operator to scale the ADC result from 0-1023
' to 0-500. The */ performs a divide by 256 automatically, allowing math
' which would normally exceed the limit of a word variable.

' Connect analog input to channel-0 (RA0)

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

' Define LCD registers and bits
Define LCD_DREG  PORTD
Define LCD_DBIT  4
Define LCD_RSREG PORTE
Define LCD_RSBIT 0
Define LCD_EREG  PORTE
Define LCD_EBIT  1

' Define ADCIN parameters
Define ADC_BITS     10 ' Set number of bits in result
Define ADC_CLOCK    3  ' Set clock source (3=rc)
Define ADC_SAMPLEUS 50 ' Set sampling time in uS

adval Var Word         ' Create adval to store result

   TRISA = %11111111   ' Set PORTA to all input
   ADCON1 = %10000010  ' Set PORTA analog and right justify result
   Low PORTE.2         ' LCD R/W line low (W)
   Pause 500           ' Wait .5 second

mainloop:
   Adcin 0, adval      ' Read channel 0 to adval (0-1023)
   adval = (adval */ 500)>>2 ' Equates to: (adval * 500)/1024

   LCDOut $fe, 1       ' Clear LCD
   LCDOut "DC Volts= ",DEC (adval/100),".", DEC2 adval ' Display the decimal value  
   Pause 100           ' Wait .1 second
   Goto mainloop       ' Do it forever

   End