sst39vf400a.txt

SST 系列Nor flash 的读写源码

;                         that is, a multiple of 2048.
;
; Output:
;       None
; =====================================================================

Erase_One_Sector        proc    near

        push    ax                              ; save register

        mov     es:word ptr [5555h], 0AAAAh	; send 6-byte code for
        mov     es:word ptr [2AAAh], 05555h	; sector erase
        mov     es:word ptr [5555h], 08080h
        mov     es:word ptr [5555h], 0AAAAh
        mov     es:word ptr [2AAAh], 05555h
        mov     ax, 03030h
        mov     word ptr es:[di], ax

        call    Delay_25_Milli_Seconds		; insert delay = Tse

        pop     ax                              ; restore register

        ret

Erase_One_Sector        endp


; =====================================================================
; PROCEDURE:    Erase_One_Block
;
; This procedure can be used to erase a block, or total of 32K words,
; in the SST39VF400A.
;
; Input:
;       es:di   points to the beginning address of the "Destination" 
;               block which will be erased.
;               ==> Note: The address MUST be on a block boundary,
;                         that is, a multiple of 32K.
;
; Output:
;       None
; =====================================================================

Erase_One_Block         proc    near

        push    ax                              ; save register

        mov     es:word ptr [5555h], 0AAAAh	; send 6-byte code for
        mov     es:word ptr [2AAAh], 05555h	; block erase
        mov     es:word ptr [5555h], 08080h
        mov     es:word ptr [5555h], 0AAAAh
        mov     es:word ptr [2AAAh], 05555h
        mov     ax, 05050h
        mov     word ptr es:[di], ax

        call    Delay_25_Milli_Seconds		; insert delay = Tbe

        pop     ax                              ; restore register

        ret

Erase_One_Block         endp


; =====================================================================
; PROCEDURE:    Erase_Entire_Chip
;
; This procedure can be used to erase the entire contents of
; SST's SST39VF400A.
;
; Input:
;       none
;
; Output:
;       None
; =====================================================================

Erase_Entire_Chip       proc    near

        mov     es:word ptr [5555h], 0AAAAh	; send 6-byte code for
        mov     es:word ptr [2AAAh], 05555h	; chip erase
        mov     es:word ptr [5555h], 08080h
        mov     es:word ptr [5555h], 0AAAAh
        mov     es:word ptr [2AAAh], 05555h
        mov     es:word ptr [5555h], 01010h

        call    Delay_100_Milli_Seconds		; insert delay = Tsce

        ret

Erase_Entire_Chip       endp


; =====================================================================
; PROCEDURE:    Program_One_Word
;
; This procedure can be used to program ONE word of data to the SST39VF400A.
;
; NOTE:  It is necessary to first erase the sector containing the word to
;        be programmed.
;
;
; Input:
;       ax      WORD which will be written into the SST39VF400A.
;       es:di   DESTINATION address which will be written with the
;               data input in ax.
;
; Output:
;       None
;       SI, DI:  Contain their original values
; =====================================================================

Program_One_Word          proc    near

        push    ax                              ; save registers
        push    ds
        mov     ax, ABS_SEGMENT                 ; set up the ds register
        mov     ds, ax
        mov     ds:word ptr [5555h], 0AAAAh     ; send 3 byte data protection
        mov     ds:word ptr [2AAAh], 05555h     ;  sequence to the chip
        mov     ds:word ptr [5555h], 0A0A0h
        pop     ds                              ; restore the byte to be
        pop     ax                     		;  programmed from stack
        mov     word ptr es:[di], ax            ; program the byte
        call    check_Toggle_Ready              ; wait for valid TOGGLE bit

        ret

Program_One_Word          endp


; =====================================================================
; PROCEDURE:    Program_One_Sector
;
; This procedure can be used to program a memory sector, or total of 
; 2048 words, of the SST39VF400A.
;
; Input:
;       ds:si   SOURCE address containing the data which will be
;               written into the SST39VF400A.
;       es:di   DESTINATION address which will be written with the
;               data passed in for ds:si
;
; Output:
;       None
;       SI, DI:  Contain their original values
; =====================================================================

Program_One_Sector        proc    near

        push    ax              ; save registers
        push    bx
        push    di
        push    si
        pushf                   ; preserve the "Direction" flag
        cld                     ; clear "Direction" flag to
                                ;  auto-increment SI and DI
;
; Erase the sector before programming.  Each erase command will erase a total
; of 2048 words for the SST39VF400A
;
        call    Erase_One_Sector
;
; The following loop will program a total of 2048 words to the SST39VF400A
;
        mov     cx, SECTOR_SIZE
POS1:
        push    ds
        mov     ax, ABS_SEGMENT
        mov     ds, ax
        mov     ds:word ptr [5555h], 0AAAAh    ; send 3-byte SDP sequence
        mov     ds:word ptr [2AAAh], 05555h
        mov     ds:word ptr [5555h], 0A0A0h
        pop     ds

        lodsw                           ; get the word to be programmed
        mov     bx, di                  ; preserve original DI temporarily
        stosw                           ; program the word
        push    di                      ; preserve incremented DI temporarily
        mov     di, bx			; restore original DI
        call    check_Toggle_Ready      ; wait for TOGGLE bit to get ready
        pop     di                      ; retrieve the updated DI
        loop    POS1                    ; continue program more words until done
;
; Restore the registers' value from the stack
;
        popf                            ; restore original direction flag
        pop     si                      ; restore registers
        pop     di
        pop     bx
        pop     ax

        ret

Program_One_Sector        endp


; =====================================================================
; PROCEDURE:    Program_One_Block
;
; This procedure can be used to program a memory block, or a total of 
; 32K words, of the SST39VF400A.
;
; Input:
;       ds:si   SOURCE address containing the data which will be
;               written into the SST39VF400A.
;       es:di   DESTINATION address which will be written with the
;               data passed in for ds:si
;
; Output:
;       None
;       SI, DI:  Contain their original values
; =====================================================================

Program_One_Block         proc    near

        push    ax              ; save registers
        push    bx
        push    di
        push    si
        pushf                   ; preserve the "Direction" flag
        cld                     ; clear "Direction" flag to
                                ;  auto-increment SI and DI
;
; Erase the block before programming.  Each erase command will erase a total
; of 32K words of the SST39VF400A.
;
        call    Erase_One_Block
;
; The following loop will program a total of 32K words to SST's SST39VF400A
;
        mov     cx, BLOCK_SIZE
POB1:
        push    ds
        mov     ax, ABS_SEGMENT
        mov     ds, ax
        mov     ds:word ptr [5555h], 0AAAAh     ; send 3-byte SDP sequence
        mov     ds:word ptr [2AAAh], 05555h     
        mov     ds:word ptr [5555h], 0A0A0h
        pop     ds

        lodsw                           ; get the word to be programmed
        mov     bx, di                  ; preserve DI temporarily
        stosw                           ; program the word
        push    di                      ; preserve incremented DI temporarily
        mov     di, bx			; restore original DI
        call    check_Toggle_Ready      ; wait for TOGGLE bit to get ready
        pop     di                      ; retrieve the updated DI
        loop    POB1                    ; continue program more words until done

        popf                            ; restore original direction flag
        pop     si                      ; restore registers
        pop     di
        pop     bx
        pop     ax

        ret

Program_One_Block         endp


;======================================================================
; PROCEDURE:                    Check_Toggle_Ready
;
; During the internal program cycle, any consecutive read operation
; on DQ6 will produce alternating 0抯 and 1抯, i.e. toggling between
; 0 and 1. When the program cycle is completed, the DQ6 data will
; stop toggling. After the DQ6 data stops toggling, the device is ready
; for the next operation.
;
; Input:
;       es:di   must already be set-up by the caller
;
; Output:
;       None
;======================================================================

Check_Toggle_Ready      proc    near

        push    ax              ; save registers
        push    bx

        mov     ax, es:[di]     ; read a word from the chip
        and     ax, 4040h       ; mask out the TOGGLE bit (DQ6)
CTR_Tog2:
        mov     bx, es:[di]     ; read the same word from the chip again
        and     bx, 4040h       ; mask out the TOGGLE bit (DQ6)
        cmp     ax, bx          ; is DQ6 still toggling?
        je      CTR_Tog3        ; No, then the write operation is done
        xchg    ax, bx          ; YES, then continue checking...
        jmp     short CTR_Tog2
CTR_Tog3:
        pop     bx              ; restore registers
        pop     ax

        ret

Check_Toggle_Ready      endp


;=======================================================================
; PROCEDURE:                    Check_Data_Polling
;
; During the internal program cycle, any attempt to read DQ7 of the last
; byte loaded during the page/byte-load cycle will receive the complement 
; of the true data.  Once the program cycle is completed, DQ7 will show 
; true data.
;
; Input:
;       es:di   must already be set-up by the caller
;       bx      contains the original (true) data
;
; Output:
;       None
;
;=======================================================================

Check_Data_Polling      proc    near

        push    ax              ; save registers
        push    bx

        and     bx, 8080h       ; mask out the DQ7 bit
CDP_Tog2:
        mov     ax, es:[di]     ; read a word from the chip
        and     ax, 8080h       ; mask out the DQ7 bit
        cmp     ax, bx          ; is DQ7 still complementing?
        jne     CDP_Tog2

        pop     bx              ; restore registers
        pop     ax

        ret

Check_Data_Polling      endp