Holtek HT-IDE, Руководство пользователя

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baudrate equ baudrateconst ;replace baudrate with baudrateconst
tx equ txpin ;replace txpin with tx
rx equ rxpin ;replace rxpin with rx
sdata .section ’data’ ;
count db ? ;serial bit counter
txreg db ? ;transmit data register
rcreg db ? ;receive data register
delay db ? ;delay counter
serial .section ’code’ ;
transmit proc ;transmit a byte (Acc)
mov txreg,a ;hold Acc at txreg
mov a,baudrate ;load delay counter
mov delay,a ;
clr tx ;send start bit ’0’
mov a,9 ;load bit counter
mov count,a ;
txdelay: ;
sdz delay ;delay to fit baudrate
jmp txdelay ;
mov a,baudrate ;reload delay counter
mov delay,a ;
sdz count ;if transmit over?
jmp sendbit ;no. send next bit
jmp endtx ;yes. go ahead
sendbit:
rrc txreg ;shift right through carry flag
snz c ;is ’1’
jmp lobit ;no. goto lobit
set tx ;yes. send ’1’
jmp txdelay ;repeat from txdelay
lobit: ;
clr tx ;send ’0’
jmp txdelay ;repeat from txdelay
endtx: ;
nop ;delay for a while
nop ;
set tx ;send stop bit ’1’
t1: ;
sdz delay ;delay between bits
jmp t1 ;(timing adjustment)
mov a,baudrate ;
mov delay,a ;
t2: ;
sdz delay ;
jmp t2 ;
ret ;
transmit endp ;
receive proc ;receive a byte
sz rx ;if start bit ’0’
HT-IDE User’s Guide
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