Microcontroller User's Guide

USER’S GUIDE
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;This code example shows how to initialize the serial port and transmit /
; receive code as described above.
TA Equ 0C7h
MCON Equ 0C6h
Org 00h
Reset :
SJMP Start
Org 23h
Serial_ISR :
CLR RI ;Clear receive flag
CLR TI ;Clear transmit flag
RETI ;No special processing, return to application
Org 30h
Start :
MOV TA, #0AAh ;Start Timed Access
MOV TA, #55h ; finish Timed Access
MOV MCON, #88h ;Select Partition at 4000h (DS5000)
CLR RI ;Initialize receive flag
CLR TI :Initialize transmit flag
MOV SCON, #50h ;Configure Serial Port for Mode 1 and enable receiver
MOV TMOD, #20h ;Configure the Timer 1 for 8–bit auto–reload
MOV TCON, #40h ;Enable the Timer 1
MOV TH1, #0FDh ;Set Baud Rate
ANL PCON, #7Fh ;Set SMOD=0
MOV IP, #10h ;Set Serial Interrupt to high priority
MOV IE, #90h ;Globally enable interrupts and Serial Interrupt
Send :
MOV R0, #0FFh ;Set loop counter to 255
MOV DPTR, #4000h ;Put the data pointer at the beginning of data memory
Send_Loop :
MOVX A, @DPTR ;Get data byte
MOV SBUF, A ;Transmit data byte
JNB TI, $ ;Wait for serial word to be sent (interrupt)
INC DPTR ;Next byte to be sent
DJNZ R0, Send_Loop ;Decrement loop counter
Receive :
JNB RI, $ ;Wait for incoming word (interrupt)
MOV R1, SBUF ;Get received byte
CJNE R1, #0A5h, Send ;Check for confirmation code
; and resend all data if wrong
End