;******************************************************************************
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;well as to civil liability for the breach of the terms and         
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;THIS SOFTWARE IS PROVIDED IN AN "AS IS" CONDITION. NO WARRANTIES,  
;WHETHER EXPRESS, IMPLIED OR STATUTORY, INCLUDING, BUT NOT LIMITED  
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; *******************************************************************
; PICkit 2 Lesson 4 - "A2D"
;
; This shows how to read the A2D converter and display the
; High order parts on the 4 bit LED display.
; The pot on the Low Pin Count Demo board varies the voltage 
; coming in on in A0.
;
; The A2D is referenced to the same Vdd as the device, which 
; is provided by the USB cable and nominally is 5V.  The A2D
; returns the ratio of the voltage on Pin RA0 to 5V.  The A2D
; has a resolution of 10 bits, with 1023 representing 5V and
; 0 representing 0V.
;
; *******************************************************************
; *    See 44-pin Demo Board User's Guide for Lesson Information    *
; *******************************************************************

#include <p16F887.inc>
	__CONFIG    _CONFIG1, _LVP_OFF & _FCMEN_OFF & _IESO_OFF & _BOR_OFF & _CPD_OFF & _CP_OFF & _MCLRE_OFF & _PWRTE_ON & _WDT_OFF & _INTRC_OSC_NOCLKOUT
	__CONFIG    _CONFIG2, _WRT_OFF & _BOR21V

     cblock 0x20
Delay1           ; Assign an address to label Delay1
Delay2
Display          ; define a variable to hold the diplay
temp1
temp2
     endc
          
     org 0
Start:
     bsf       STATUS,RP0     ; select Register Bank 1
     movlw     0xFF
     movwf     TRISA          ; Make PortA all input
     clrf      TRISD          ; Make PortD all output
	 clrf	   TRISB
     movlw     0x00           ; Left Justified, Vdd-Vss referenced
     movwf     ADCON1
     banksel	ANSEL     ; select Register Bank 3
     movlw     0xFF           ; we want all Port A pins Analog
     movwf     ANSEL
     bcf       STATUS,RP0     ; back to Register Bank 0
     bcf       STATUS,RP1
     bsf	   PORTB,1		  
     movlw     0x41			  
     movwf     ADCON0         ; configure A2D for Fosc/8, Channel 1 (RA1), and turn on the A2D module
	 movlw	   0x00
	 movwf	   PORTD
MainLoop:
	bsf		ADCON0,2
	bcf		ADCON0,3
     nop                      ; wait 5uS for A2D amp to settle and capacitor to charge.
     nop                      ; wait 1uS
     nop                      ; wait 1uS
     nop                      ; wait 1uS 
     nop                      ; wait 1uS
     bsf       ADCON0,GO_DONE ; start conversion
     btfss     ADCON0,GO_DONE ; this bit will change to zero when the conversion is complete
     goto      $-1

     movf      ADRESH,w       ; Copy the display to the LEDs
	movwf		temp1
	bcf		ADCON0,2
	bsf		ADCON0,3
     nop                      ; wait 5uS for A2D amp to settle and capacitor to charge.
     nop                      ; wait 1uS
     nop                      ; wait 1uS
     nop                      ; wait 1uS 
     nop                      ; wait 1uS
     bsf       ADCON0,GO_DONE ; start conversion
     btfss     ADCON0,GO_DONE ; this bit will change to zero when the conversion is complete
     goto      $-1

     movf      ADRESH,w       ; Copy the display to the LEDs
	movwf		temp2
;	subwf		temp1,w
     movwf     PORTD
     goto      MainLoop

     end