Phần này mình xin giới thiệu về mạch giao tiếp và 1 chuơng trình asm giao tiếp DS1307 ở trang 8051projects.info
Lưu ý code chỉ mang tính tham khảo để các bạn hiểu rõ hơn cách giao tiếp với DS1307.
Code
;%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
; PORT DECLERATION
;%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
SDA EQU P3.5 ;SDA=PIN5
SCL EQU P3.4 ;SCL=PIN6
DS1307W EQU 0D0H ; SLAVE ADDRESS 1101 000 + 0 TO WRITE
DS1307R EQU 0D1H ; SLAVE ADDRESS 1101 000 + 1 TO READ
; **********************************************************
; Main Program
; **********************************************************
CALL OSC_CONTROL ;Initilize the RTC
REPEAT: CALL READ_CLOCK ;Read Clock
AJMP REPEAT
; **********************************************************
; SUB SETS THE DS1307 OSCILLATOR
; **********************************************************
OSC_CONTROL:
ACALL SEND_START ; GENERATE START CONDITION
MOV A,#DS1307W ; 1101 0000 ADDRESS + WRITE-BIT
ACALL SEND_BYTE ; SEND BYTE TO 1307
MOV A,#00H ; ADDRESS BYTE TO REGISTER 00H
ACALL SEND_BYTE ; SECONDS REGISTER, ALWAYS LEAVE
SETB LASTREAD ; REG 00H-BIT #7 = 0 (LOW)
ACALL SEND_STOP ; IF REG 00H-BIT #7 = 1 CLOCK
ACALL SEND_START ; OSCILLATOR IS OFF.
MOV A,#DS1307R ; 1101 0001 ADDRESS + READ-BIT
ACALL SEND_BYTE ;
ACALL READ_BYTE ; READ A BYTE FROM THE 1307
CLR ACC.7 ; CLEAR REG 00H-BIT #7 TO ENABLE
OSC_SET: ; OSCILLATOR.
PUSH ACC ; SAVE ON STACK
ACALL SEND_STOP ;
ACALL SEND_START ;
MOV A,#DS1307W ; SETUP TO WRITE
ACALL SEND_BYTE ;
MOV A,#00H ; REGISTER 00H ADDRESS
ACALL SEND_BYTE ;
POP ACC ; GET DATA TO START OSCILLATOR
ACALL SEND_BYTE ; SEND IT
ACALL SEND_STOP
RET
; **********************************************************
; THIS SUB CONTROLS THE SQW OUTPUT 1HZ
; **********************************************************
SQW_CONTROL_1HZ:
LCALL SEND_START ; SEND START CONDITION
MOV A,#DS1307W ; SET POINTER TO REG 07H ON
; DS1307
LCALL SEND_BYTE
MOV A,#07H
LCALL SEND_BYTE
MOV A,#90H ; SQW/OUT ON AT 1HZ
JNB SQW,SQW_SET ; JUMP IF SQW BIT IS ACTIVE
MOV A,#80H ; TURN SQW/OUT OFF – OFF HIGH
SQW_SET:
LCALL SEND_BYTE
LCALL SEND_STOP
RET
; **********************************************************
; THIS SUB READS ONE BYTE OF DATA FROM THE DS1307
; **********************************************************
READ_BYTE:
MOV BITCNT,#08H; SET COUNTER FOR 8-BITS DATA
MOV A,#00H
SETB SDA ; SET SDA HIGH TO ENSURE LINE
; FREE
READ_BITS:
SCL_HIGH ; TRANSITION SCL LOW-TO-HIGH
MOV C,SDA ; MOVE DATA BIT INTO CARRY
RLC A ; ROTATE CARRY-BIT INTO ACC.0
CLR SCL ; TRANSITION SCL HIGH-TO-LOW
DJNZ BITCNT,READ_BITS
; LOOP FOR 8-BITS
JB LASTREAD,ACKN
; CHECK TO SEE IF THIS IS
; THE LAST READ
CLR SDA ; IF NOT LAST READ SEND ACK-BIT
ACKN:
SCL_HIGH ; PULSE SCL TO TRANSMIT ACKNOWLEDGE
CLR SCL ; OR NOT ACKNOWLEDGE BIT
RET
; **********************************************************
; SUB SENDS START CONDITION
; **********************************************************
SEND_START:
SETB _2W_BUSY ; INDICATE THAT 2-WIRE
CLR ACKS ; OPERATION IS IN PROGRESS
CLR BUS_FLT ; CLEAR STATUS FLAGS
JNB SCL,FAULT
JNB SDA,FAULT
SETB SDA ; BEGIN START CODITION
SCL_HIGH
CLR SDA
ACALL DEELAY
CLR SCL
RET
FAULT:
SETB BUS_FLT
RET
; **********************************************************
; SUB SENDS STOP CONDITION
; **********************************************************
SEND_STOP:
CLR SDA
SCL_HIGH
SETB SDA
CLR _2W_BUSY
RET
; **********************************************************
; SUB DELAYS THE BUS
; **********************************************************
DEELAY:
NOP ; DELAY FOR BUS TIMING
RET
; **********************************************************
; THIS SUB SENDS 1 BYTE OF DATA TO THE DS1307
; CALL THIS FOR EACH REGISTER SECONDS TO YEAR
; ACC MUST CONTAIN DATA TO BE SENT TO CLOCK
; **********************************************************
SEND_BYTE:
MOV BITCNT,#08H; SET COUNTER FOR 8-BITS
SB_LOOP:
JNB ACC.7,NOTONE; CHECK TO SEE IF BIT-7 OF
SETB SDA ; ACC IS A 1, AND SET SDA HIGH
JMP ONE
NOTONE:
CLR SDA ; CLR SDA LOW
ONE:
SCL_HIGH ; TRANSITION SCL LOW-TO-HIGH
RL A ; ROTATE ACC LEFT 1-BIT
CLR SCL ; TRANSITION SCL LOW-TO-HIGH
DJNZ BITCNT,SB_LOOP; LOOP FOR 8-BITS
SETB SDA ; SET SDA HIGH TO LOOK FOR
SCL_HIGH ; ACKNOWLEDGE PULSE
CLR ACKS
JNB SDA,SB_EX ; CHECK FOR ACK OR NOT ACK
SETB ACKS ; SET ACKNOWLEDGE FLAG FOR
; NOT ACK
SB_EX:
CALL DEELAY ; DELAY FOR AN OPERATION
CLR SCL ; TRANSITION SCL HIGH-TO-LOW
CALL DEELAY ; DELAY FOR AN OPERATION
RET
; **********************************************************
; SUB READS THE CLOCK AND WRITES IT TO THE SCRATCHPAD MEMORY
; ON RETURN FROM HERE DATE & TIME DATA WILL BE STORED IN THE
; DATE & TIME REGISTERS FROM 24H (SECS) TO 2AH (YEAR)
; ALARM SETTINGS IN REGISTERS 2CH(HRS) AND 2DH(MINUTES).
; **********************************************************
READ_CLOCK:
MOV R1,#SECS ; SECONDS STORAGE LOCATION
MOV BYTECNT,#00H
CLR LASTREAD
CALL SEND_START
MOV A,#DS1307W
CALL SEND_BYTE
MOV A,#00H
CALL SEND_BYTE
CALL SEND_STOP
CALL SEND_START
MOV A,#DS1307R
CALL SEND_BYTE
READ_LOOP:
MOV A,BYTECNT
CJNE A,#09H,NOT_LAST
SETB LASTREAD
NOT_LAST:
CALL READ_BYTE
MOV @R1,A
MOV A,BYTECNT
CJNE A,#00H,NOT_FIRST
MOV A,@R1
CLR ACC.7 ; ENSURE OSC BIT=0 (ENABLED)
MOV @R1,A
NOT_FIRST:
INC R1
INC BYTECNT
MOV A,BYTECNT
CJNE A,#0AH,READ_LOOP
CALL SEND_STOP
RET
;&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
;(((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((
; STORE THE TIME TO RTC CHIP
;(((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((
STORE_RTC:
LCALL SEND_START ; SEND 2WIRE START CONDITION
MOV A,#DS1307W ; LOAD DS1307 WRITE COMMAND
LCALL SEND_BYTE ; SEND WRITE COMMAND
MOV A,#01H ; SET DS1307 DATA POINTER TO BEGINNING
LCALL SEND_BYTE ; OF 00H
MOV A,MINS ; Send min
LCALL SEND_BYTE
MOV A,HRS ;send hr
SETB ACC.6 ;12 HR MODE
JNB AMS,YUH
CLR ACC.5 ;AM/PM 1=PM,0=AM
AJMP YUH1
YUH: SETB ACC.5
YUH1: LCALL SEND_BYTE
MOV A,DAY ; Send Day
LCALL SEND_BYTE
MOV A,DATE1 ; Send date
LCALL SEND_BYTE
MOV A,MONTH ; Send month
LCALL SEND_BYTE
MOV A,YEAR ; Send yr
LCALL SEND_BYTE
LCALL SEND_STOP ; SEND 2WIRE STOP CONTION
RET
;$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
Theo ktmk.byethost8.com
