;;
;; isa0.ASM
;;
;; RomaNets Software
;;
;;
;; Board_#8 (28 pins) ( Veroboard) PIC16F873
;; 20MHz _HS_Generator
;;
;; Using only 8 bit ADC (MSB)
;;
;;
;; Syncronous serial protocal
;; RA2 - data
;; RA3 - sync _-
;;
;;
;; RB0 - LCDData
;; RB1 - LCDSync _-
;; RB2 - Podlozhka control LCDPCtrl
;;
;; We have two variants to display contents of the byte:
;; 	1) call ConvertByte2ThreeDecDigits 	- 0..255
;; 	2) call ConvertByte2TwoHexDigits	- 0..FF


	;LIST P=16F870, R=DEC
	;INCLUDE "C:\Program Files\MPLAB IDE\MCHIP_Tools\p16f870.inc"
	LIST P=16F873, R=DEC
	INCLUDE "C:\Program Files\MPLAB IDE\MCHIP_Tools\p16f873.inc"


;; PORTA
DData	EQU	0x02		; do not used in this ex
DSync	EQU	0x03
DLAY	EQU	10
;; PORTB
LCDData	 EQU	0x00
LCDSync	 EQU	0x01
LCDPCtrl EQU	0x02



;  Register Usage
 CBLOCK 0x20
 _w
_status

Count
Count2
Count3

digit1
digit2
digit3
digit4

digitemp
count1

;_LCD_number
;AD_TWO_MSBits
;_LCD_digit2
;cnt_ChangeDigit
LCD_state
LCDLoader_count
LCDLoader_digitemp
 bin
 hundreds
 tens_and_ones
tmp_hex
;skip_interrupt_cnt
 ENDC

					;_RC_OSC
					;_XT_OSC
 PAGE
 __CONFIG _CP_OFF & _DEBUG_OFF & _CPD_OFF & _LVP_OFF & _BODEN_OFF &_HS_OSC & _PWRTE_ON  & _WDT_OFF
                                ;  Note that the WatchDog Timer is OFF



;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;  Code
  	org 0
  	goto Init
  	
  	org 4
;==========================================================
; Interrupt handler
;==========================================================
  	movwf	_w
  	movf	STATUS, w
  	movwf	_status

	bcf		INTCON, T0IF

  	
  	movf	_status, w
  	movwf	STATUS
  	swapf	_w, f
  	swapf	_w, w
  	retfie
;;
;; End of interrupt handler





;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
Init
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

	bsf		STATUS, RP0			; bank 1
	;	movlw	0xFF				; init RA0-RA5 for input
	;	movwf	TRISA & 0x7F
		movlw	0x00				; init RB0-RB7 for output
		movwf	TRISB & 0x7F
		movlw	0x00				; init RC0-RC7 for output
		movwf	TRISC & 0x7F
		
		;ADC
		movlw	0x02				; analog input on AN1/AN0, ADFM - left justified
		;movlw	0x82				; analog input on AN1/AN0, ADFM - right justified
		movwf	ADCON1 & 0x7F

		; 0xD4	- prscaler 0111 1/256
		; 1,843,200 Hz /4 /256 (=1800))/32(0xD4) = 56.25 Hz  28.125 Hz for LCD

		; 0xD3	- prscaler 0111 1/256
		; 1,843,200 Hz /4 /256 (=1800))/16(0xD3) =112.5 Hz	 56.25 Hz for LCD

		; 0xD7	- prscaler 0111 1/256
		; 20,000,000 Hz /4 /256 /256(0xD7) = 76 Hz	38 Hz for LCD
	
		; 0xD3	- prscaler 0011 1/16
		; 1,000,000 Hz /4 /256 /16(0xD3) = 61 Hz	30 Hz for LCD
		;20,000,000 Hz /4 /256 /16(0xD3) = 1220 Hz	610 Hz for LCD
		; 0xD2	- prscaler 0010 1/8
		; 1,000,000 Hz /4 /256 /8(0xD2) = 122 Hz
		; 0xD1	- prscaler 0001 1/4
		; 1,000,000 Hz /4 /256 /4(0xD1) = 244 Hz
		; 0xD0	- prscaler 0000 1/2
		; 1,000,000 Hz /4 /256 /2(0xD0) = 488 Hz
		movlw	0xD7				; use timer, no RBPU, edge don't care
		movwf	OPTION_REG & 0x7F	; prescaler to TMR0(not WDT) LS_3_Bits 
	bcf		STATUS, RP0			; bank 0


;	clrf	TMR0
;	movlw	0xA0				; enable TMRO
;	movwf	INTCON
	
	clrf	LCD_state
	;movlw	2
	;movwf	skip_interrupt_cnt


	movlw 	0xFF
	movwf	PORTB
	movlw 	0xFF			; light off all LEDs
	movwf	PORTC


;//////////////////////////////////////////////////////////
MainCycle
;//////////////////////////////////////////////////////////
	;; Calculation of delay: 20,000,000 / 4 / 2631720 = 3.8 Hz

;; TEST BEGIN
;; TEST END


;	;movlw	0xFF				; 256 * 1280 + 1280 = 328960
;	movlw	0x1
;	movwf	Count2
;OuterDelayCycle
;	decfsz	Count2, f
;		goto InnerDelayCycle
;	goto CodeAfterDelay
	
;InnerDelayCycle
;	;movlw	0xFF				; 256 * (1+1+1+2) = 1280
;	movlw	0x1
;	movwf	Count1
;	decfsz	Count1, f
;		goto $-1
;	goto OuterDelayCycle



CodeAfterDelay
	movlw	0xFF
	xorwf	PORTC, f


	;movlw	0x81				; ADC enable	Fosc/32  ?kHz
	movlw	0xC1				; ADC enable	inner 250 kHz
	;movlw	0x01				; ADC enable	Fosc/2
	movwf	ADCON0
	movlw	25					; delay == 20mks
	;movlw	3					; delay == 20mks	with Fosc = 1.8432 MHz
	;movlw	2					; delay == ?mks	    with Fosc = 1.8432 MHz
	
	addlw	0xFF  ; 1 ; 4*25 * [(1/(20,000,000/4))==0.2mks] = 20
						  ; 4*3 * [(1/( 1,843,200/4))==2.17mks] = 26
						  ; 4*2 * [(1/( 1,843,200/4))==2.17mks] = 26
	btfss	STATUS, Z ; 1 ;
		goto	$-2	  	  ; 2 ;
	bsf		ADCON0, GO
	btfsc	ADCON0, GO
	goto	$-1
	
	movf	ADRESH, w
	
	movwf	PORTB

	goto MainCycle
		


	end