read_write.asm

DS1302的驱动程序。主程序用C语言编写

	RST	EQU	P3.7
	SCLK	EQU	P3.5
	IO	EQU	P3.6

	

	PUBLIC		_WRITE1302_BYTE
	WRITE1302_BYTEP	SEGMENT	CODE
	RSEG		WRITE1302_BYTEP

_WRITE1302_BYTE:
	CLR	SCLK
	CLR	RST
	NOP
	NOP
	SETB	RST
	NOP
	NOP
	MOV	A,R7
	LCALL	WRITE_BYTE
	MOV	A,R5
	LCALL	WRITE_BYTE
	CLR	SCLK
	CLR	RST
	RET

	PUBLIC		_READ1302_BYTE
	READ1302_BYTEP	SEGMENT	CODE
	RSEG		READ1302_BYTEP

_READ1302_BYTE:
	CLR	SCLK
	CLR	RST
	NOP
	NOP
	SETB	RST
	NOP
	NOP
	MOV	A,R7
	LCALL	WRITE_BYTE
	LCALL	READ_BYTE
	CLR	SCLK
	CLR	RST
	MOV	R7,A	
	RET

WRITE_BYTE:
	MOV	R2,#8
W1:	CLR	SCLK
	RRC	A
	MOV	IO,C
	NOP
	NOP
	NOP
	NOP
	SETB	SCLK
	DJNZ	R2,W1	
	RET

READ_BYTE:
	MOV	R2,#8
RE1:	CLR	SCLK
	NOP
	NOP
	NOP
	NOP
	MOV	C,IO
	RRC	A
	SETB	SCLK
	NOP
	NOP
	DJNZ	R2,RE1
	RET

	end