software USART

hello,

I need to implement a software USART in FX2 using Port E.I have program for UART. I wanted to include a clock to it . I have sync problem. More over Iam not able to assign port E for FX2 in KEIL . It has port 0,1,2,3 only.Iam using assembler program. Iam posting the code .Any help will be appricated

PUBLIC _putc

txd_pin EQU     P3.7            ;Transmit on this pin
CS EQU          P3.3            ;CHIP SELECT
clk EQU         P3.0            ;CLK

//;Formula to calculate the bit time delay constant
;This constant is calculated as: (((crystal/baud)/12) - 5) / 2
;crystal is the frequency of crystal in Hz
;baud is required baudrate
;Please try to keep baudrate below 9600
;to get best results :-)

BITTIM  EQU    45;             (((11059200/9600)/12) - 5) / 2

LOOkUp:  DB 03H,05H




_main: MOV DPTR,#0000 ;load address from lable
         CLR CLK
         CLR CS
         MOV R2,#1
         lcall _putc

_putc:  CLR A ;clear A
        MOVC A,@A+DPTR ;load data from address pointed by A+DPTR
        MOV R1,#8               ;Send 8 bits

putc1:
        RRC A
        MOV txd_pin,C           ;write next bit
        SETB CLK
        MOV R0,#BITTIM          ;Wait full bit-time
        DJNZ R0,$               ;For DATA bit
        CLR CLK
        MOV R0,#BITTIM          ;Wait full bit-time
        DJNZ R0,$               ;For DATA bit
        DJNZ R1,putc1           ;write 8 bits      INC DPTR

        DJNZ R2,_putc
        SETB CS                ;Set chip select line high
        ;CLR A
         MOV DPTR,#0000 ;load address from lable
         RET                        ;For STOP bit
         END

Punitha