i2c.inc

<BIOS研发技术剖析>书的源代码,包括完整的BIOS汇编语言源程序.

;        shl     al, 03h
	mov	al,00011000b
        call    PreCsI2CWrite

        mov     cx, 007ffh
        call    DelayBase01

        call    CsI2CDummy

;        pop	dx
	pop	cx
	pop	ax
        ret
RvDvAcktoTm ENDP


;-----------------------------------------------------------------------;
;                       SeqRdDvAcktoTm                                  ;
;-----------------------------------------------------------------------;
; Receiver send ACK to Transmitter when sequential read.                ;
;-----------------------------------------------------------------------;
SeqRdDvAcktoTm  PROC    PUBLIC
        push	ax
	push	cx
;	push	dx

;        mov     dh, 00000000b   ; I2C data , this is for Receiver ACK cycle
;        mov     dl, 00000001b   ; I2C clock
;        mov     al, 00h
;        or      al, dh
;        shl     al, 01h
;        or      al, dl
;        shl     al, 03h
	mov	al,00001000b	
        call    PreCsI2CWrite

        mov     cx, 07ffh
        call    DelayBase01

        call    CsI2CDummy

;        pop	dx
	pop	cx
	pop	ax
        ret
SeqRdDvAcktoTm  ENDP


;-----------------------------------------------------------------------;
;                       ChkAck                                          ;
;-----------------------------------------------------------------------;
; Wait the slave to assert data to low for acknowledge.                 ;
; Input : None                                                          ;
; Output:                                                               ;
; Register destroyed: None                                              ;
;-----------------------------------------------------------------------;
ChkAck          PROC    PUBLIC
        push	ax
	push	cx

        mov     ah, 06dh
        call    read_sio_byte
        or      al, 00010000b           ;I2C bus data active level high
        call    write_sio_byte

        mov     cx, 05ffh
        call    DelayBase01

        mov     cl, 010h
NoAckW:
        dec     cx
        jz      WaitAckTimOut
        mov     al, 00h                 ;This is for Transmitter ACK cycle
        call    CsI2CRead
        test    al, 00010000b
        jnz     NoAckW

        clc
        jmp     short EndWaitAck

WaitAckTimOut:
        stc

EndWaitAck:
        pop	cx
	pop	ax
        ret
ChkAck          ENDP


;-----------------------------------------------------------------------;
;                       PreEnableI2CBus                                 ;
;-----------------------------------------------------------------------;
; Set the GPIO to default high.                                         ;
; Input : None                                                          ;
; Output: None                                                          ;
; Register destroyed: None                                              ;
;-----------------------------------------------------------------------;
PreEnableI2CBus PROC    PUBLIC
        push	ax
	push	cx

        mov     ah, 06dh
        call    read_sio_byte
        or      al, 00011000b           ;I2C bus data/clock active level high
        call    write_sio_byte

        mov     cx, 07ffh
        call    DelayBase01

        pop	cx
	pop	ax
        ret
PreEnableI2CBus ENDP


;-----------------------------------------------------------------------;
;                       EnableI2CBus                                    ;
;-----------------------------------------------------------------------;
; Input : None                                                          ;
; Output: None                                                          ;
; Register destroyed: None                                              ;
;-----------------------------------------------------------------------;
EnableI2Cbus    PROC    PUBLIC
        push	ax
        mov     ah, 06dh
        call    read_sio_byte
        or      al, 00000100b           ;Enable I2C bus control
        call    write_sio_byte
        pop	ax
        ret
EnableI2CBus    ENDP


;-----------------------------------------------------------------------;
;                       DelayBase                                       ;
;-----------------------------------------------------------------------;
; Input : (CX) Delay count                                              ;
; Output: (CX) = 0                                                      ;
; Register destroyed: CX                                                ;
;-----------------------------------------------------------------------;
DelayBase:
        jmp     short $+2
DelayBase01:
        jmp     short $+2
        jmp     short $+2
        jmp     short $+2
        jmp     short $+2
        jmp     short $+2
        loop    DelayBase
        ret
;;==========================================================================;;
;; Input: AH = Device Slave Address
;;	  AL = Device Register Index
;; Output:AL = Register Value
;; Destroy:None
i2c_read_byte proc public

	push	cx
	push	dx

	mov	cx, ax

        call    PreEnableI2CBus         ;I2C bus Data/Clock active level High
        call    EnableI2CBus            ;Enable I2C bus

        call    StrI2CCycle

        call    CsI2CDummy
	
        mov     ah, 08h          	; Device Slave Address
        mov     dh, ch		 	; I2C data (/W)
        mov     dl, 11111111b    	; I2C clock
        call    csI2CCmd

        call    ChkAck

        call    CsI2CDummy

        mov     dh, cl		 	; I2C data (Device Register Index)
        call    csI2CCmd
	
        call    ChkAck

        call    CsI2CDummy

        call    StrI2CCycle

        call    CsI2CDummy
	
        mov     dh, ch			; I2C data
	or	dh, 01h			; (Read) 
        call    csI2CCmd

        call    ChkAck

        call    CsI2CDummy

	mov	ah, ch				; Restore AH

	mov	cx,8
	mov	dl,0
read_loop:
	shl	dl,1
	call	CSI2CRead
	test	al,10h
	jz	read_data_low
	or	dl,1
read_data_low:
	loop	read_loop

	mov	al, dl				; AL = Read Data

	call	RvDvAcktoTm

        call    CsI2CDummy

        call    PreStpI2CCycle

        mov     cx, 0ffffh
        call    DelayBase01

	pop	cx
	pop	dx
	ret
i2c_read_byte endp
;;==========================================================================;;
;; Input: AH = Device Slave Address
;;	  AL = Device Register Index
;;	  CL = Write Data
;; Output:None
;; Destroy:None
i2c_write_byte proc public

	push	cx
	push	dx

	mov	ch, ah

        call    PreEnableI2CBus         ;I2C bus Data/Clock active level High
        call    EnableI2CBus            ;Enable I2C bus

        call    StrI2CCycle

        call    CsI2CDummy
	
        mov     ah, 08h          	; Device Slave Address
        mov     dh, ch		 	; I2C data (/W)
        mov     dl, 11111111b    	; I2C clock
        call    csI2CCmd

        call    ChkAck

        call    CsI2CDummy

        mov     dh, al		 	; I2C data (Device Register Index)
        call    csI2CCmd
	
        call    ChkAck

        call    CsI2CDummy

        mov     dh, cl			; I2C data
        call    csI2CCmd		; Write Data

        call    ChkAck

        call    CsI2CDummy

	mov	ah, ch				; Restore AH

        call    PreStpI2CCycle

        mov     cx, 0ffffh
        call    DelayBase01

	pop	cx
	pop	dx
	ret
i2c_write_byte endp
;;==========================================================================;;