MCU-Serial port communication with PC

;First, send characters to the MCU through the serial port debugging tool, i.e., the PC. After the MCU receives the data, it sends it to the PC. 

; Observe the transmission result again through the serial port debugging tool, that is, the transmission and reception from PC to MCU is realized

;Due to local simulation, a virtual serial port needs to be installed. The PC uses COM1 port, and the MCU's COMPIM is set to COM2. The baud rate is 9600

        org 0000h

        ajmp main

        org 0023h

        ajmp aa

        org 0030h

main: mov scon, #50h ; Set the MCU serial port mode 1 to receive

        mov tmod,#20h ;Timer T1 works in timing mode 2

        mov pcon,#00h ;Serial port baud rate SMOD=0,Fosc=11.0592M

        mov th1,#0fdh ; Timer T1 initial value = FDH, generating 9600 baud rate

        mov tl1,#0fdh

        setbea

        set b es  

        setb tr1

        CLR F0; F0 = 0 receive

        mov a,sbuf ; start serial port to receive data

        sjmp $

aa: JB F0,TRS

        SETB F0

        clr ri ; Clear the RI flag after receiving a data

        MOV SCON,#40H ; Set the MCU serial port mode 1 to send

        MOV SBUF,A ; Start the serial port to send data

        RETI                

TRS: CLR TI ; Clear the TI flag after sending a data

        CLR F0

        MOV SCON,#50H ; Set the MCU serial port mode 1 to receive

        mov A,sbuf ; start serial port to receive data   

        RETI    

        end