Ok.

Its not really a secret.  What I thought I figured out was why it was not =
=20
working.
"I thought I knew".  What I figured out was a way to make the USB work, by
not using .NET to communicate with the USB COM4 port.  Instead I use a =20
proxy "helper"
program to be the interface between the USB COM4 port and the .NET user =20
interface.

Here is what I found out:
1. The PIC18F8722 firmware works absoulutely positively flawlessly with =20
the 9 pin RS-232
interface via a MAX232 RS-232 to CMOS level converter IC.  It has worked =20
with no errors for weeks
using this interface, pretty much 24 x 7.  For this reason the PIC =20
firmware is very solid
-- All I need it for the USB to work identical to this dumb simple voltage =
=20
level converter.

2. I have programmed everything strictly in 8 bit binary mode.  I have =20
never used the text
mode in any of the code I wrote for the PC.  The PIC code is entirely in =20
assembly, and
one would have to really try to have it understand text mode.  It was =20
enough work trying
to get the 8 bit packets work so that I had guaranteed detection of when a =
=20
packet started
and stopped, without using an extra hardware signal line -- So I could use =
=20
this with the
USB which does not support RTS and CTS signalling.

3. Sometimes the USB interface does not even work with the Hyperterminal.  =
=20
This usually
happens if I leave the USB plugged in and turn off the PC.  I don't have =20
all the
answers about what to do if this happens.  What always seems to work is to =
=20
plugin the
PICKIT3 ISD into the USB PIC18LF2450 and then do a verify of the flash =20
memory against the
..HEX file several times.  Also one time I unplugged the USB connctor from =
=20
the computer,
removed power, restored power, then plugged the USB back into the computer =
=20
-- that did work
the one time I tried it.

4. There really is something going on very differently using the .NET.  =20
The same settings,
including binary mode, barely work at all with .NET.  Thes same settings =20
work quite well with
the helper program I wrote in Visual C++ 6.0 with MFC and Win32 APIs.  =20
This uses the MSCOMM 6.0
Active X object, which barely works with .NET.  The built-in SerialPort =20
object of .NET: I have never
gotten this for getting data from the PIC into the PC via USB =20
(PIC18LF2450) at all, NEVER.

5. My current new setup is now using an "helper" interface program written =
=20
in Visual C++ 6.0 that
communicates both with the PIC and the .NET user interface program.  The =20
"helper" program and the
..NET user interface use WM_COPYDATA messages, a send my HWND message, and =
=20
system cache-backed
memory file mapping IO (CreateFileMapping and MapViewOfFile) communicate =20
with each other, sending
packets of data.  The "helper" program uses the MSCOMM 6.0 Active X and =20
API, the Win32 and the
MFC Api, to communicate with the PIC.   The PIC18F8722 has exactly the =20
same firmware used
for weeks with the MAX232 RS-232 level converer interface.  This setup is =
=20
working.

6. I cannot deny that the PIC18LF2450 firmware may have problems.  This =20
was demonstration code
that came with the PICDEM PIC18 EXPLORER DEMONSTRATION BOARD.  I think the =
=20
code is supplied
"as is" with no warranties.  I do not have source code, just the HEX =20
file.  It would be major
effort to debug with just the HEX file.

7. I would like a better USB interface.  I am looking for source code -- =20
maybe drop the serial
interface paradigm altogether.  Have the USB deliver data in wider than 8 =
=20
bit chunks, having
extra bits for control and signaling.  The 9 bit PIC serial interface is =20
actually very good
as the extra bit can be used for addressing and packet demarcation, I do =20
use the second
USART in the PIC18F8722 this way, highly successfully.  The extra bit =20
means packets don't need
escape symbols and special symbols to guarantee packet demarcation.  A PC =
=20
USB interface with
9 bits per "word" (or more) would be great.

I thank everyone for there input.
Dena Meier



--=20
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