Systematic Management of Data Files in AT24C512-EEWORLD

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The file system program source code is as follows:

. Common subroutines:

RD24C: Read the contents of the AT24C512 cell pointed to by DPTR and put it into the RAM cell pointed to by (R1, R0). R6 is the data length.

WR24C: Write the contents of the RAM cell pointed to by (R1, R0) to the AT24C512 cell pointed to by DPTR, R6 is the data length

WR_ONE: Write the contents of the RAM unit pointed to by DPTR to the AT24C512 unit pointed to by DPTR

TZDPTR: MUL AB; DPTR=DPTR+A*B

ADD A, DPL

MOV DPL, A

MOV A, DPH

ADDC A, B

MOV DPH, A

RET

AT24C512 system formatting: Initialize the directory area and page allocation area to 0EEEEH

AT_INIT: MOV DPTR, #AT24C

MOV R7, #80H

MOV A, #0EEH

ATINIT1:MOVX @DPTR, A

INC DPTR

DJNZ R7, ATINIT1

MOV R7, #54

ATINIT2:MOV DPTR, #AT24C

MOV R1, DPH

MOV R0, DPL

MOV R6, #80H

MOV A, R7

MOV B, #80H

MOV DPTR, #0

LCALL TZDPTR

PUSH 7

LCALL WR24C

POP 7

DJNZ R7, ATINIT2

RET

For ease of operation, the contents of the directory area and the page allocation area are read into the same address of RAM each time the computer is turned on. The procedure is as follows:

R_HEAD:CLR IE.7

MOV R5, #0

RHEAD1:MOV A, R5

MOV B, #80H

MOV DPTR, #0

LCALL TZDPTR

MOV R1, DPH

MOV R0, DPL

MOV R6, #80H

PUSH 5

LCALL RD24C

POP 5

INC R5

CJNE R5, #54, RHEAD1

SETB IE.7

RET

The procedure for adding files is as follows:

YB_SAVE: MOV PAGE_NO,#0 AGES=number of pages required

MOV DPTR, #AT_FAT AGE_NO is the number of free pages

YBSAVE1: MOVX A, @DPTR ; AT_FAT is the starting address of the page allocation table

CJNE A, #0EEH, YBSAVE2

INC PAGE_NO

YBSAVE2: INC DPTR

INC DPTR

MOV A, PAGE_NO

CLR C

SUBB A, PAGES

JZ YBSAVE4

MOV A, DPH

CJNE A, #1BH, YBSAVE1; 1B00H is the end address of the page allocation table

YBSAVE3: LCALL ERRDSP; Display error message

RET

YBSAVE4: MOV R7, #0

YBSAVE5: MOV DPTR, #YB_BEG; YB_BEG is the starting address of the directory area

MOV A, R7

MOV B, #10

LCALL TZDPTR

MOVX A, @DPTR

CJNE A, #0EEH, YBSAVE16

SJMP YBSAVE6

YBSAVE16: INC R7

CJNE R7, #153, YBSAVE5; can store up to 153 files

SJMP YBSAVE3 ; Already full

YBSAVE6: CLR IE.7

PUSH 7; save the sequence number of the free directory area found

LCALL DO_DSP ; Display "Storing"

MOV DPTR, #AT_FAT

YBSAVE7: MOVX A, @DPTR

CJNE A, #0EEH, YBSAVE8

SJMP YBSAVE9

YBSAVE8: INC DPTR

INC DPTR

SJMP YBSAVE7

YBSAVE9: PUSH DPH; find the first free page and protect the address

PUSH DPL

MOV R1, DPH

MOV R0, DPL

MOV A, #0FFH

MOVX @DPTR, A

INC DPTR

MOVX @DPTR, A ; temporarily treat it as the last page of the file

PUSH DPH

PUSH DPL

PUSH 0

PUSH 1

LCALL WR_ONE

POP 1

POP 0

POP DPL

POP DPH

INC DPTR

MOV R7, PAGES

DEC R7

MOV A, R7

JZ YBSAVE13; If only one page is needed, the page allocation table modification ends

YBSAVE10: MOVX A, @DPTR

CJNE A, #0EEH, YBSAVE11

PUSH DPH

PUSH DPL

MOV DPH, R1; R1, R0 is the page allocation table address of the previous page

MOV DPL, R0

POP 0

POP 1

MOV A, R1

MOVX @DPTR, A

INC DPTR

MOV A, R0

MOVX @DPTR, A ；Write the new address to the address unit of the previous page

PUSH 0

PUSH 1

PUSH 7

LCALL WR_ONE; write the modification information to AT24C512

POP 7

POP 1

POP 0

MOV DPH, R1

MOV DPL, R0

INC DPTR

SJMP YBSAVE12

YBSAVE11: INC DPTR

INC DPTR

YBSAVE12: DJNZ R7, YBSAVE10

MOV DPH, R1

MOV DPL, R0

MOV A, #0FFH

MOVX @DPTR, A

INC DPTR

MOVX @DPTR, A ; write 0FFFFH, indicating the end of file allocation

LCALL WR_ONE

YBSAVE13: POP 0

POP 1

POP 0

POP 1; R1R0 = DPTR = the first free page found

POP ACC; ACC=R7=free directory area number

PUSH ACC

MOV DPTR, #YB_BEG+8

MOV B, #10

LCALL TZDPTR ; Determine the address of the directory free area

MOV A，R1

Keywords：AT24C512 Reference address：Systematic Management of Data Files in AT24C512

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