list p=18f452
include p18f452.inc

;## PART A
;Write an assembly subroutine to configure the ADC to use reference voltages Vdd and Vss. Analog Channels 2 and 3 will have some analog device on it.
;## PART B
;Write an assembly subroutine that:
;- Samples analog channel 2, and places the left justified result in the variable `analog2H:analog2L`
;- Samples analog channel 3, and places the left justified result in the variable `analog3H:analog2H`
;All variables must be placed in data memory bank 1.
;## PART C
;Explain why the PIC18 Analog to Digital converter is termed a 'ratiometric' converter

;# ADC QUESTION 2


UDATA	0x100
analog2H    res 2
analog2L    res 2
analog3H    res 2
analog3L    res 2
     ; Declare a code section at 0x0 named 'RST'. This instruction sends the
    ; program to the actual start of the program.
RST code    0x0030
    GOTO    Setup

    ; Declare a code section at 0x0030. This is where the actual program logic will start
SRT code    0x0080


Setup:
    clrf    PORTA           ; Clear PORTB
    BSF	    TRISA, 2
    BSF	    TRISA, 3

    movlw   B'01000000'     ; Fosc/8, A/D enabled
    IORLW   B'010'	    ;Channel 2
   ; IORLW   B'011'	    ;Channel 3
    movwf   ADCON0

    movlw   B'00001110'     ; Left justify, 1 analog channel
    movwf   ADCON1          ; VDD and VSS references
	MOVLB 01 	;slect BAnk 1



Main:
    bsf     ADCON0, GO      ; Start A/D conversion
    call WaitForAdConversion



ReadFirst:
    MOVF    ADRESH, W	    ; Store value from the potentiometer
    MOVWF   analog2H, BANKED
    MOVF    ADRESL, W	    ; Store value from the potentiometer
    MOVWF   analog2L, BANKED	    ; Send as the 'on time' for the wave
    MOVLW   0x0F	    ;Clear the channel bits
    ANDWF   ADCON0
    MOVLW   B'011'	    ;Channel 3
    movwf   ADCON0
     bsf     ADCON0, GO
     call WaitForAdConversion



ReadSecond:
    MOVF    ADRESH, W	    ; Store value from the potentiometer
    MOVWF   analog2H, BANKED
    MOVF    ADRESL, W	    ; Store value from the potentiometer
    MOVWF   analog2L, BANKED	    ; Send as the 'on time' for the wave
    goto    Main	    ; Repeat the process



 WaitForAdConversion:
    btfss   PIR1, ADIF      ; Wait for conversion to complete
    goto    WaitForAdConversion
    return


    end