Mitsubishi DS5000TK, DS907x SIP manual Application Using the DS2251T RTC DS1283 Example, 159

USER'S GUIDE

APPLICATION: USING THE DS2251T RTC (DS1283 EXAMPLE)

The DS2251T or DS2252T use the DS1283 Byte±wide type real±time clock (RTC). This clock is accessed in a parallel fashion like a RAM. The user simply writes to the registers to set the time and control functions. The fol- lowing program is an example of how to use this clock. It provides a serial port interface allowing an user to set

and read the time of day. Note that the serial port setup expects 9600 baud communication and an 11.0592 MHz crystal. If a user's application uses different val- ues, this setup must be modified. All of the timekeeping access is performed in the code under Set Time and Tell Time. The remainder of this program concerns getting data in and out of the serial port for display purposes and has nothing to do with timekeeper access.

;Program DS1283

;This program responds to commands received over the serial

;port to set the date and time information in the DS1283

;

;The program first initializes the serial port for communication

;at 9600 baud with eight data bits, no parity, and one stop bit.

;After setting the date and time, the program begins execution

;of an infinite loop which sends back the date and time each

;time a character is received.

;
CR	EQU	0DH
LF	EQU	0AH
;
MCON	EQU	0C6H
TA	EQU	0C7H
	CSEG	AT	0
;
	MOV	TA,	#0AAH	; Timed
	MOV	TA,	#55H	;	access.
	MOV	PCON,	#0	; Reset watchdog timer.
	ANL	MCON,	#0FBH	; Turn off PES for memory access.
	MOV	P2,	#0	; Clear high byte of address.
			;	for clock access
;
	MOV	IE,	#0
	MOV	TMOD,	#20H	; Initialize the
	MOV	TH1,	#0FAH	;	serial port
	MOV	TL1,	#0FAH	;	for 9600
	ORL	PCON,	#80H	;	baud, with 11.0522 MHz crystal.
	MOV	SCON,	#52H
	MOV	TCON,	#40H
;Messages
	MOV	DPTR,	#TEXT0
	LCALL	TEXT_OUT
	LCALL	CHAR_IN
	LCALL	CHAR_OUT
	PUSH	ACC
	MOV	DPTR,	#TEXT3
	LCALL	TEXT_OUT
	POP	ACC
	ANL	A,	#5FH
	CJNE	A, #'Y',	TELL_TIME

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