LAB7 Using the 8051 Serial Port and Interrupts Overview The purpose of this lab

Question

LAB7 Using the 8051 Serial Port and Interrupts Overview The purpose of this lab is to control and program the serial port of the micro-controller in a given sequence. Two switches SW1 and SW2 are connected to the micro-controller input port bits P1.1 and P1.2. The two switches define the required Baud rate requirements for the serial communication as follows: SW1 SW2 Baud (bps) 10 1200 2400 1 0 4800 1 9600 Steps First, write a subroutine "BCODE" (Baud Code) starting at code address 100H to detect the setting of SW1 and SW2 and return a value in accumulator B (0 for 1200, 1 for 2400, 2 for 4800, and 3 for 9600 Baud). It also setup the TH1 register for the requested BAUD rate. 2.Second, write a subroutine "CONFIG Timers, Interrupts, and Serial Configuration) starting at code address 160H to configure the serial port for Mode 1, timer 0 for mode 1, and timer 1 for mode 2. Also it enables the timer 0 interrupt and start timer 0 and timer 1. 3 Third, write a subroutine "SDISPLAY (Serial Display) starting at code starting address of 200H to display on the serial port the message "SERIAL BAUD IS XXXX BPS. "XXXX" s the actual Baud rate value selected. The subroutine will use polling on the TI flag.

Explanation / Answer

sw1 equ p1.0
org 0h
main:   mov tmod,#20h
        mov th1,#-3
        mov scon,#50h
        setb tr1
        setb sw1
sb1:    jb sw1,next
        mov dptr,#mess1
fn:     clr a
        movc a,@a+dptr
        jz sb1
        acall sendcom
        inc dptr
        sjmp fn
next:   mov dptr,#mess2
ln:     clr a
        movc a,@a+dptr
        jz sb1
        acall sendcom
        inc dptr
        sjmp ln
sendcom:mov sbuf,a
here:   jnb ti,here
        clr ti
        ret

end

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