Microcontroller User's Guide

USER’S GUIDE
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lcall CLOSE ;Close date/time registers.
mov IE, #0
mov TMOD, #20H ;Initialize the
mov TH1, #0FAH ;serial port
mov TL1, #0FAH ;for 9600
orl PCON, #80H ;baud using 11.0592 MHz crystal.
mov SCON, #52H
mov TCON, #40H
L:
jnb RI, L ;Wait for character.
clr RI ;Clear the receiver.
mov A, SBUF ;Load in the character.
cjne A, #’R, H ;Skip if not a read.
lcall OPEN ;Set up to read date/time.
mov B #8 ;Set up to send 8 bytes.
F:
lcall RBYTE ;Read a byte of date/time.
G:
jnb TI, G ;Wait for end of previous send.
clr TI ;Clear transmitter.
mov SBUF, A ;Send out the byte.
djnz B, F ;Loop for 8 bytes.
sjmp L ;Return to main loop.
H:
cjne A, #’W’, J ;Skip if not a write.
lcall OPEN ;Set up to read date/time.
mov B, #8 ; Set up to receive 8 bytes.
I:
jnb RI, I ;Wait to receive a byte.
clr RI ;Clear the receiver.
mov A, SBUF ;Bring in the byte.
lcall WBYTE ;Write a byte of date/time.
djnz B, I ;Loop for 8 bytes.
sjmp L ;Return to main loop.
J:
jnb TI, J ;If it is neither an R nor a W
clr TI ;increment the character,
inc A ;send it back out to the
mov SBUF, A ;serial port, and then
sjmp L ;return to the main loop.
;
;
; SUBROUTINE TO OPEN THE CLOCK/CALENDAR (ECC)
;
; This subroutine executes the sequence of reads and writes which
; is required in order to open communication with the timekeeper.
; The subroutine returns with the timekeeper opened for data
; access with both the accumulator and B register modified.
;