Phytec miniMODUL-537, Hardware Manual

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The Serial Interface
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PHYTEC Meßtechnik GmbH 1993 L-006e_2
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6.8 Program Example for the Serial Interface
The given examples use no interface interrupts, but test only the
interface flags RI and TI.
6.8.1 Program for SERIAL0
; Example of the initialization for the utilization of the
; internal baud rate generator for 12 MHz system-clock frequency.
init: setb BD ; Select internal BD-generator
orl PCON,#80H ; Set bit SMOD for 9600 baud
; Alternative: anl PCON,#7FH for 4800
; baud
mov S0CON,#5AH ; Mode-adjustment and initialization
; of the flags RI0 and TI0 8
; data bit, no parity, 1 start bit,
; 1 stop bit TI0 set, RI0 erased.
init_end: ...
...
; Example of the initialization for the utilization of timer 1
; as baud rate generator for a system-clock frequency
; of 11.059 MHz.
ch0_in: ; Subroutine to read a character
jnb RI0,ch_in ; Wait until character accepted
clr RI0
mov a,S0BUF
ret
; character in ACC
ch0_out: ; Subroutine to output a character
; Output character in ACC
jnb TI0,ch_out ; Wait until ready for transmission
clr TI0,ch_out
mov S0BUF,a
ret
init: clr BD ; not necessary after a RESET
anl TMOD,#0FH
orl TMOD,#20H
; Mode 8 bit, autoreload
orl PCON,#80H ; Set bit SMOD Baud
; Alternative: anl PCON,#7FH
mov TH1,#232 ; Reload value for 2400 baud for SMOD=1
setb TR1 ; Start timer 1
movb S0CON,#5AH ; Mode adjustment and initialization of
; flags RI0 and TI0 8 data bit, no
; parity, 1 start bit, 1 stop bit set
; TI0, Erase RI0
init_end: ...