Sorry, I need to be a little more specific.

My project already has TXD and RXD coming out via a MAX202 for RS232 level
conversion. These lines have a shared function. They allow control of the
project as well as updating of firmware.

What I am looking for is this.....

1) At production, project is supplied with bootloader pre-programmed into
PIC16F876 via ICSP.

2) Project is supplied with Windows package that does 2 things...
          A) Allows operating code (for project to perform required
functions) to be uploaded
            B) Allows testing of unit once operating code is loaded
3) When project is powered it is in either of 2 states.
          A) No operating code has been uploaded (bootloader only is
programmed)
          B) Operating code is programmed and running

4) In Case A of "3", The bootloader receives commands and bytes from the
bit-bashed serial
   link to program the Operating code into Flash ROM.
5) In Case B of "3", The operating code responds to commands via the
bit-bashed serial link
   (eg. Switch LED ON, Read ADC etc). It will also respond to commands to
upload new Operating
   code. In this case it will call the bootloader programming handler.

The source for the operating code will normally be written in C (Hi-Tech)
which has power-up sequence at start of memory that requires shifting by the
bootloader.

Regards

David Huisman

-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Byron A Jeff
Sent: Monday, July 30, 2001 10:03 PM
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [PIC]: Bootloader using Bit Bashed IO and C Source


On Mon, Jul 30, 2001 at 08:48:25AM +1000, David Huisman wrote:
> I require a bootloader that utilizes BIT BASHED com to PC instead of using
> on-board UART. (Note: the IO MUST be bit-bashed as the UART is already
being
> used by the project).
>
> The files that will be uploaded to the micro with the bootloader are
written
> in C.
> The compiler is HI-TECH C. The bootloader is programmed into micro using
> MPLAB and the PICSTART PLUS programmer.
>
> Would someone advise if they have done this exact thing or comment on
> whether the code below placed in my C source and used in conjunction with
> ROMZAP would do the trick.
>
> #asm
> psect powerup, class=CODE, delta=2
> global powerup, start
> powerup:
> org 0x3
> goto start
> #endasm
>
> void main()
> {
>      /* C code to go here */
>  }

Take a look at wloader.

http://www.xs4all.nl/~wf/wouter/pic/wloader/

Bit bashed and doesn't require any change in your code. It'll automagically
move the code out of the reset vector area.

BAJ

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