I have a project I'm working that features the 16c73 (scaled down 16c74),
specifically using its built-in uart. The project is essentially a portable
data logging device. Data is stored in a serial eeprom. To extract the data,
you plug your PC into the  device, and a proprietary exchange protocol sucks
the data out of the monitor and on to the PC's disk. So far so good.

The problem is this: The act of "plugging" the pc's serial cable into the
data logger will sometimes generate some noise. The uart apparently gets
confused, and all serial communication is crippled before it even really starts.

To get around this, I tried to insert some code which will look for noise or
data errors (coming from noise) immediately after the logger senses that the
pc's cable has been plugged in. (It is written in the Parallax dialect and
looks something like this:

                ;*** Look for Comm Errors *********************
:rx             clrb    RP0             ;bank 0 registers
                jb      OERR,:er1       ;if rx overrun or
                jb      FERR,:er2       ;if framing error jump
                jmp     :sd1            ;proceed if no error

                ;*** process  UART errors **************
:er1            clrb    RP0
                mov     Tmp2,#050h      ;set freq for gleep
                lcall   gleep           ;generates a brief tone
                jmp     :comerr

:er2            clrb    RP0
                mov     Tmp2,#000h      ;set freq for gleep
                lcall   gleep           ;generates a brief tone
                jmp     :comerr


:comerr         clrb    RP0             ;bank 0 registers

                clrb    CREN            ;*reset receive logic
                setb    CREN            ;*reset receive logic
                setb    SPEN            ;*force enable of serial port
                mov     w,RCREG         ;pull byte out of receiver
                jmp     :rx

:sd1            clrb    RP0             ;continue with rest of the code:

Some explanation is in order. This code contains lcalls to a subroutine
called "gleep" which generates a musical note through a piezo speaker. I was
using this for diagnostic purposes in order to determine what type of com
errors are really being detected. The problem is, this code doesnt work as
expected.

If the com error is an overrun, the code cycles and seems to recover ok. If
the error is a framing error, however, it ends up going into and endless
loop, as though FERR can't be reset or something.

The final piece to the puzzle: If I send a few characters to the logger
while its locked in this loop, it does break out and continue. What this
means, however, is that the first data packet sent to the logger following
"plug-in" will likely be corrupted.

Ultimately, my question is this: If I plug in and generate noise in the
process, how can I *really* clear the uart and its flags before I start any
dialog? Any tips or suggestions would be greatly appreciated.

P.S. BRGH=0