Using AT93C56A as EEPROM with 89c51

[Reborn121]

I need to write a simple program to erase, read, and write a value in assembly language using the EEPROM AT93C56A with the 89c51RB2...can anyone help me get started please? This is really urgent! Thank you for any assistance.

 

[IanP]

Here are working subs for the 93C06, and as the 93C56 belongs to the same family, this may be a good starting point ..

; Reads and writes 93C06
; P1.0		=		EEProm CS
; P1.1		=		EEProm Clk
; T0			=		EEProm Din/Dout


; EEPROM routines summmary:


;			E_Read...reads a byte from EEProm of a given address...
;			E_Write...writes a byte to EEProm to a given address...
;			Ee_Rd_8b...reads a byte from EEProm at given location
;			Ee_Wr_8b...writes a byte to EEProm at given location...
;			Ee_Clock...time delay for EEloops...

; This reads a byte from EEprom at a given location..

E_Read:		SETB	EECs			; CS is ON...
			LCALL	Ee_Clock
			SETB	EEDin			; DI is H...
			LCALL	Ee_Clock
			MOV	A, EEAddress
			ANL	A, #3Fh
			ORL	A, #80h		; Code and address for read...
			LCALL	Ee_Wr_8b		; Send address...
			LCALL	G_Time
			LCALL	Ee_Rd_8b		; Read a byte..
			CLR	EECs			; CS is OFF...
			RET

; This writes a byte to EEProm..

E_Write:		SETB	EECs				; CS is on..
			LCALL	Ee_Clock
			SETB	EEDin				; Din goes H
			LCALL	Ee_Clock
			MOV	A, #30h			; Code for WE = 11
			LCALL	Ee_Wr_8b
			CLR	EEDin
			CLR	EECs

			LCALL	G_Time

			SETB	EECs
			LCALL	Ee_Clock
			SETB	EEDin
			LCALL	Ee_Clock
			MOV	A, EEAddress
			ANL	A, #1Fh			; 0011 1111
			ORL	A, #40h
			LCALL	Ee_Wr_8b			; Send code and 6bit address to EE
			MOV	A, EEData
			LCALL	Ee_Wr_8b
			CLR	EEDin
			CLR	EECs

			LCALL	G_Time

			SETB	EECs
			JNB	EEDout, $
			CLR	EECs

			LCALL	G_Time

			SETB	EECs				; CS is on..
			LCALL	Ee_Clock
			SETB	EEDin				; Din goes H
			LCALL	Ee_Clock
			MOV	A, #00h			; Code for WDis = 00
			LCALL	Ee_Wr_8b
			CLR	EEDin
			CLR	EECs
			RET

; This reads 8 bits from EEProm...

Ee_Rd_8b:		MOV	R7, #08h
Ee_R_Loop:		LCALL	Ee_Clock
			MOV	C, EEDout
			RLC	A
			DJNZ	R7, EE_R_Loop
			MOV	R7, #7Fh
Rd_T_Loop:		NOP
			NOP
			DJNZ	R7, Rd_T_Loop
			RET

; This writes 8 bits to EEProm...

Ee_Wr_8b:		MOV	R7, #08h
Ee_8_Loop:		RLC	A
			MOV	EEDin, C
			LCALL	Ee_Clock
			DJNZ	R7, Ee_8_Loop
			CLR	EEDin
			MOV	R7, #7Fh
Wr_T_Loop:		NOP
			NOP
			DJNZ	R7, Wr_T_Loop
			RET

; EE_Clock time delay...

Ee_Clock:		SETB	EEClk
			MOV	R6, #10h
Ee_H_Loop:		NOP
			NOP
			NOP
			NOP
			DJNZ	R6, Ee_H_Loop
			CLR	EEClk
G_Time:		MOV	R6, #10h
Ee_L_Loop:		NOP
			NOP
			NOP
			NOP
			DJNZ	R6, Ee_L_Loop
			RET

; ====================================

IanP

 

[Reborn121]

Thanks for your post...i have tried to get as much code together as i could for my application...my specific requirements are to erase the EEPROM, read a value in variable EEADR and store in EEBYT then output the value to port 2 of the micro. Can anyone tell me if im on the right track or offer suggestions,,i know its not complete? Thanks

.equ sk, p1.0    ;serial clock
.equ di, p1.1    ;data input
.equ do, p1.2    ;data output
.equ cs, p1.3    ;chip select
;__________________________________________

         Mov SCON, #50H       ;serial mode
	 Mov TMOD, #20H       ;timer1 mode2

;__________________________________________

;Read a byte from EEPROM
;__________________________________________

Read:    SETB   cs             ;cs is set
         LCALL  Clock
         SETB   di             ;di is set
         LCALL  Clock
         MOV    A, EEADR
         ANL    A, #3Fh
         ORL    A, EEBYT       ;code and address for read
         LCALL  wr_byt         ;send address
         LCALL  Time
         LCALL  rd_byt         ;read a byte
         CLR    cs             ;cs is set
         RET                   ;return
;___________________________________________
         

;Write byte to EEPROM 
;__________________________________________   

Write:   SETB   cs             ;cs is set
         LCALL  Clock
         SETB   di             ;di is set
         LCALL  Clock
         MOV   A, #30h        
         LCALL   wr_byt
         CLR   di              ;clear di
         CLR   cs              ;clear cs

         LCALL  Time

         SETB   cs             ;cs is set
         LCALL  Clock
         SETB   di             ;di is set
         LCALL  Clock
         MOV    A, EEADR
         ANL    A, #1Fh         
         ORL    A, #40h
         LCALL  wr_byt      
         MOV    A, EEBYT
         LCALL  wr_byt
         CLR    di             ;clear di
         CLR    cs             ;clear cs

         LCALL Time

         SETB  cs              ;cs is set
         JNB   do, $
         CLR   cs              ;clear cs

         LCALL  Time

         SETB   cs             ;cs is set
         LCALL  Clock
         SETB   di             ;di is set
         LCALL  Clock
         MOV    A, #00h         
         LCALL  wr_byt
         CLR    di             ;clear di
         CLR    cs             ;clear cs
         RET                   ;return
;____________________________________________________________

;Clock time delay
;____________________________________________________________

Clock:   SETB  sk              ;clock is set
         MOV   R6, #10h        ;move 10 hex into reg 6

H_Loop:  NOP
         NOP
         NOP
         NOP
         DJNZ  R6, H_Loop
         CLR   sk              ;clear clock

L_Loop:  NOP
         NOP
         NOP
         NOP
         DJNZ  R6, L_Loop
         RET                    ;return

Time:    Mov R6,#10H
;____________________________________________________________