Programming for the SCI interface
 

I'm new to assembly language and have written an instruction sequence for the MC68HC12 ,to input a string of characters using the SCI channel 0. The input character string, will be no more than 20 characters, and will be stored in memory when an EOT character is received.
Port A bit 0 will be used for parity error detection.

The serial data transfer will be performed according as follows;
o 19,200 baud (P clock is 8 MHz)
o one start bit, 8 data bits, one stop bit
o polled output
o idle line wakeup
o short idle line mode
o no loop back
o characters should be encoded using odd parity

Is this the correct approach and how would I add an interrupt driven input?

        org           $800

address                rmb        20

        movb        #$00,SCOBDH        ; set baud rate to 19,200

        movb        #$26,SCOBDL

        movb        #$03,SCOSR1        ; M=0, Wake=0, ILT=0, PE=1 & PT=1

        movb        #$08,SCOSR2        ; TE=1

        movb        #$00,DDRB        ; initialize Port A as input



gets_sc0        jsr        getc_sc0

                ldx        address        

                cmpa        #$04

                beq        exit

                staa        1,x+

                bra        gets_sc0



exit                clr        0,x

                swi



getc_sc0        brclr        SCOSR1, $20,*        ; wait until RDRF is set

                ldaa        SCODRL        ; read character

                rts