SFCF		DATA    0B1H	; Flash Configuration
SFCM		DATA    0B2H	; Flash Command
SFAL		DATA    0B3H	; Flash Address Low
SFAH		DATA    0B4H	; Flash Address High
SFDT		DATA    0B5H	; Flash Data
SFST		DATA    0B6H	; Flash Status

;************************************************************************
;* 	MCU IAP Commands 	                 		*
;************************************************************************
SFCM_SE    	EQU	0BH	; Sector-Erase IAP cmd
SFCM_VB    	EQU	0CH	; Byte-Verify  IAP cmd
SFCM_PB		EQU	0EH	; Byte-Program IAP cmd

;************************************************************************

ORIG_DATA       EQU     R6
;************************************************************************
;* 	                     MAIN PROGRAM                             	*
;************************************************************************
   
        org  00000h       	
	ljmp main		 

	org  2000h
main:	mov  PSW, #0         	; select register bank 0
	

start:	anl  SFCF,   #10111111b	; BFh--> force IAPEN=0
;	orl  SFCF,   #10000000b ; VIS=1
;	mov  SFDT,   #0         ; Enter any value other than 55h
	mov  dptr, #1f00h ;load destination addr. 
	lcall	sector_erase	   ; erase the bytes before write to them
;=====================================================================	

 
        mov a,#00h
         
        mov dptr,#1f20h                    
loop:                     
	mov  ORIG_DATA, a	
	lcall byte_pgm		; write a byte from ACC to dest address

	lcall verify_byte	; read back the byte written to destination
	xrl  a, ORIG_DATA       ; compare with original data
        jnz  ERROR		; jump to ERROR if verification fails

Stop:
	ajmp Stop		; end of code execution

;************************************************************************
;*              	  IAP SUBROUTINES                             	*
;* 1. SECTOR-ERASE                                                      *
;* 2. BYTE-PROGRAM                                                      *
;* 3. BYTE-VERIFY                                                       *
;************************************************************************

;===================================================================
;  Subroutine of Sector Erase
;===================================================================			
sector_erase:
	orl   SFCF, #40h        ; enable IAP
	mov   SFAH, dph		; load high order address byte
	mov   SFAL, dpl		; load low order address byte
	mov   SFCM, #SFCM_SE	; issue sector erase command

busy:   mov   a,  SFST           
	jb    acc.2, busy       ; wait until flash is NOT busy.
	
safety:	                        
	anl   SFCF, #10111111b  ; disable IAP
	mov   SFDT, #0          ; any value other than 55h
	
 	ret

;=====================================================================	
; Subroutine of Byte Program
;=====================================================================
byte_pgm: 
	orl   SFCF, #40h        ; enable IAP
        mov   SFAH, dph	        ; set address to write a byte
        mov   SFAL, dpl
        mov   SFDT, ORIG_DATA   ; store data to be programmed
	mov   SFCM, #SFCM_PB	; issue program-byte cmd

done?:  mov   a,  SFST         
	jb    acc.2, done?      ; wait until byte-programming is done. 
 	ljmp  safety            
;=====================================================================
; Subroutine of Byte Verify
;=====================================================================	
verify_byte: 
	orl   SFCF, #40h        ; enable IAP
        mov   SFAH, dph  	; address from where to read a byte
        mov   SFAL, dpl
	mov   SFCM, #SFCM_VB	; issue verify_byte cmd
	nop
	mov   a, SFDT     	; data is stored in ACC
 	ljmp  safety            
;=====================================================================


ERROR:
        mov p1, #55h              ;indicating IAP failed. 

EXIT:	
	sjmp  $			



	END