;*******************************
;EEPROMwrite.asm
;How fast is EEPROM write?  Use this program to listen to the 
;frequency that is produced with 2 EEPROM writes in each cycle. 
;0 is placed in EEPROM location then read and sent to piezo.
;then 4 is placed in EEPROM, then read and sent to piezo to create tone.
;Our PIC12F629 produced a frequency of 133Hz
;  11-3-2010 
;*******************************
;
;       --+------------ +5v     
;		  |                  
;         |
;         |Vdd ---v---   
;         +---|1   Gnd|-------------+   
;             |       |             |
;          ---|GP5 GP0|--           |
;             |       |             |        
;            -|GP4 GP1|--		    |	
;             |       |     |  |    |
;           --|GP3 GP2|-----|[]|----+
;             -------       |  |    |
;            PIC12F629      piezo   |
;                                   |   
;                                   |
;    -------------------------------+-- 0v
;

	list	p=12F629
	radix	dec
	include	"p12f629.inc"
	
		errorlevel	-302	; Dont complain about BANK 1 Registers during assembly

	__CONFIG	_MCLRE_OFF & _CP_OFF & _WDT_OFF & _INTRC_OSC_NOCLKOUT  ;Internal osc.

;_MCLRE_OFF  - master clear must be off for gp3 to work as input pin 

;****************************************************************
; variables - names and files
;****************************************************************


temp1		equ 20h	;

;****************************************************************
;Equates
;****************************************************************
status		equ	0x03
rp1			equ	0x06
rp0			equ	0x05
GPIO 		equ 0x05
			

status		equ	03h
option_reg	equ 81h


		; bits on GPIO
				
pin7		equ	0	;GP0  
pin6	 	equ	1	;GP1  
pin5		equ	2	;GP2  Piezo between pin and 0v rail
pin4		equ	3	;GP3    
pin3		equ	4	;GP4  
pin2		equ	5	;GP5     
 

		;bits
				
rp0			equ	5			;bit 5 of the status register



;****************************************************************
;Beginning of program
;****************************************************************
		org		0x00
		nop
		nop
		nop
		nop
		nop			
SetUp	bsf		status, rp0 	;Bank 1			
       	movlw	b'11111000'		;Set TRIS  GP2 out   
		movwf	TRISIO	   	    ;		
		bcf		status, rp0		;bank 0
		movlw   07h         	;turn off Comparator ports
        movwf   CMCON       	;must be placed in bank 0  
		clrf 	GPIO       		;Clear GPIO of junk			
		goto 	Main	
		
		
	

;****************************************************************
;* Sub Routines 			*
;****************************************************************
		
		;read takes the value 0 or 4 from EEPROM location 127 and puts it in w
		
read		
		movlw	.127
		bsf		status,rp0			
		movwf	EEADR									
		bsf		EECON1,0	;starts EEPROM read operation storing result in EEDATA						
		movf	EEDATA,w	;move read data into w
		bcf		status,rp0				
		movwf	temp1		;temp1 has the value 0 or 4 to activate piezo on GP2
		retlw	00
		
		
		
write	
		bsf		status,rp0	;select bank1	
		movwf	EEDATA						
		bcf		status,rp0	;select bank0	
		movlw	.127
		bsf		status,rp0	;select bank1	
		movwf	EEADR			
		bsf		eecon1,wren	;enable write		
		movlw	55h 		;unlock codes
		movwf	eecon2
		movlw	0aah
		movwf	eecon2
		bsf		eecon1,wr	;write begins
		bcf		status,rp0	;select bank0		
writeA	btfss	pir1,eeif	;wait for write to complete
		goto	writeA
		bcf		pir1,eeif
		bsf		status,rp0	;select bank1
		bcf		eecon1,wren	;disable other writes
		bcf		status,rp0	;select bank0					
		retlw	00			
		
						
;****************************************************************
;* Main 							*
;****************************************************************

Main	movlw	b'00000100'		
M1		call	write
		call	read
		movf	temp1,w
		movwf	gpio
		movlw	b'00000000'		
		call	write
		call	read
		movf	temp1,w
		movwf	gpio
		goto	Main		
	
				
;****************************************************************
;*EEPROM     						*
;****************************************************************
								
		org		2100h			
					
							
		END