On Tuesday, July 03, 2001 3:39 PM, David Huisman wrote:

> I need to use that same port pin
> in my application though during running of the user code. ie.
> The Bit-Bashed com port has a dual function.
> !) Bootloader upload of new user program,
> 2) Bi-directional serial com link.

David,

i'm developing a bootloader over the internal USART. The USART is used in my
application (--> RS485), but i must be able to download a new firmware over
the same bus. This is analog to your problem. A BREAK condition is used to
signal the start of bootloading. This is done in my application USART
service. On detection the PIC starts the bootloading. Before i will
overwrite my old firmware, i must receive a preamble. If this doesn't occur,
the PIC resets.

After power-up, the PIC validate his firmware. On success the PIC starts my
application. If failed, the PIC checks for the BREAK condition.
After that the PIC continues as described above.

I think you can do the same concept of BREAK condition for signaling a
bootloading request.

Frank

-------------------------------------

GSP Sprachtechnologie GmbH
Frank Wollenberg
HW-Entwicklung
Tel.:   +49 (0)30 769929-78
Fax:    +49 (0)30 769929-12
eMail:  f.wollenberg@gsp-berlin.de



--
GSP Sprachtechnologie GmbH
Teltowkanalstr.1, D-12247 Berlin
Tel.:  +49 (0)30 769929-0
Fax:   +49 (0)30 769929-12
eMail: Info@gsp-berlin.de
Web:   http://www.gsp-berlin.de

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.