; Program RecPIC
;
; This program uses the Analogue to Digital Convertor to generate
; 8000, 8 bit samples per second. It sends these via a 115,200bps
; serial port link to a PC. The companion program "RecPIC.exe" will
; convert these samples to a ".au" file. This file can then be played
; via Windows Media Player.
;
; The PIC used is a 16F73.
; Loop length for 8000 samples/sec (125uS) and 20MHz Xtal 
; (0.2uS per instruction) is 625 Instructions
;

;Internal File Assignments
STATUS	.EQU	$03	;Used for Zero bit
PORTA	.EQU	$05
PORTB	.EQU	$06
PORTC	.EQU	$07
TXSTA	.EQU	$18
SPBRG	.EQU	$19
RCSTA	.EQU	$18
TXREG	.EQU	$19
ADRES	.EQU	$1E
ADCON	.EQU	$1F

;Internal Bit Assignments
W	.EQU	0
F	.EQU	1
GO	.EQU	2
ZERO	.EQU	2

;User File Assignments
TIMER1	.EQU	$21
COUNT	.EQU	$22
TEMP	.EQU	$23


;User Bit Assignments
GREEN     .EQU      2
RED       .EQU      3

;Program Starts Here!!!!!!!!!
         .ORG	$10

;Initialise Registers
	BSF 	3, 5
	BCF	3, 6
	MOVLW	$C0
	MOVWF	PORTC    	     ;PORTC = Output except UART
	CLRF	PORTB   	     ;PORTB = Output
	MOVLW	$FF
	MOVWF	PORTA   	     ;PORTA = Input

	MOVLW	$0A
	MOVWF	SPBRG   	     ;Set Baud Rate to 115200
	BSF	TXSTA, 2	     ;Set Baud Rate to High
	BCF	TXSTA, 4	     ;Set Async operation
	BCF	3, 5
	BSF	RCSTA, 7
	BSF	3, 5
	BSF	TXSTA, 5

	MOVLW	$04
	MOVWF	ADCON
	BCF	3, 5
	MOVLW	$80
	MOVWF	ADCON
	BSF	ADCON, 0
	
	CLRF	COUNT

;Time Loop (625 instructions total)
LOOP      MOVLW 	$10
	MOVWF	TIMER1
T0	DECFSZ	TIMER1, F
	GOTO	T0


	BSF   	ADCON, GO       
	NOP   	        	      ;Trimmer NOPs
	NOP
	NOP
	NOP
	NOP
	NOP
	NOP
	NOP
	MOVLW	$0C
	MOVWF	PORTC
	
          MOVLW	$BB	      ;BC+10=CC = 201*3 = 603+22=625
	MOVWF	TIMER1
T1	DECFSZ	TIMER1, F
	GOTO	T1
	MOVF	ADRES, W
	MOVWF	TXREG
	
	IORLW	$0F
	ADDLW	$01
	BTFSC	STATUS, ZERO
	BCF	PORTC, RED
	ADDLW	$10
	BTFSC	STATUS, ZERO
	BCF	PORTC, GREEN
	
	GOTO	LOOP
	
.END