Mitsubishi DS907x SIP User Manual page 157

OPEN: LCALL
MOV
MOV
OPENA: LCALL
XRL
LCALL
SWAP
DJNZ
RET
;
;********************************
;*** SUBROUTINE TO CLOSE THE RTC
;********************************
;
; This subroutine insures that the registers of the timekeeper
; are closed by executing 9 successive reads of the date and time
; registers. The subroutine returns with both the accumulator
; and the B register modified.
;
CLOSE: MOV
CLOSEA: LCALL
DJNZ
RET
;
;***********************************
;*** SUBROUTINE TO READ A DATA BYTE
;***********************************
;
; This subroutine performs a "context switch: to the CE2 data
; space and then reads one byte from the timekeeping device.
; Then it switches back to the CE1 data space and returns
; the byte read in the accumulator, with all other registers
; unchanged.
;
RBYTE: PUSH
PUSH
PUSH
ORL
PUSH
MOV
MOV
MOV
LI: PUSH
MOVX
RLC
POP
RRC
DJNZ
POP
POP
CLOSE ;Make sure it is closed.
B,#4 ;Set pattern period count.
A,#0C5H ;Load first byte of pattern.
WBYTE ;Send out the byte.
A,#0FFH ;Generate next pattern byte.
WBYTE ;Send out the byte.
A ;Generate next pattern byte.
B,OPENA ;Repeat until 8 bytes sent.
;Return.
B,#9 ;Set up to read 9 bytes.
RBYTE ;Read a byte.
B,CLOSEA ;Loop for 9 byte reads.
;Return.
DPL ;Save the data
DPH ; pointer on stack.
MCON ;Save MCON register.
MCON,#4 ;Switch to CE2.
B ;Save the B register.
DPL,#4 ;Set up for data input.
DPH,#0 ;Set high address byte.
B,#8 ;Set the bit count.
ACC ;Save the accumulator.
A,@DPTR ;Input the data bit from the RTC into
; ACC.7.
A ;Move it to carry.
ACC ;Get the accumulator.
A ;Save the data bit.
B,LI ;Loop for a whole byte.
B ;Restore the B register.
MCON ;Restore the MCON register.
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USER'S GUIDE
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