Are you sure you want to go through all that hassle?
Microchip provides programming service. Bootloader
preloaded into a PIC at a certain vol. does not sound
far fetch. With your program you still have to verify
your chip programming.

John



--- Bob Axtell <engineer@neomailbox.com> wrote:

> In the last two days, a potential client has
> requested something unusual. He
> asked if there is a way to include the PIC
> programmer INSIDE the product 
> PCB.
> 
> The idea is that he wants the PIC firmware to be
> update-able without any
> external hardware (such as a PIC programmer). I
> guess that he wants the
> PIC programmer to be "built-in" to the product, and
> accessible via a WinXP
> system. His reason is that the use of external
> programmers is 
> error-prone for
> the final client.
> 
> Of course the bootloader came to mind, but PICs
> don't have an internal 
> bootloader,
> so the "bootloader code" have to be programmed in
> anyway; so his 
> suggestion overrides
> the input.
> 
> So I have brainstormed the idea, and have one
> possibility as follows:
> 
> use the FT232R with pins arranged in bit-bang mode.
> Control the 12V VPP 
> switch with the
> pins, connect PGD and PGC to two other pins, and
> create a chargepump 
> with several .22uF
> ceramic caps & diodes driven by the 6M osc bit-bang
> output. It would be 
> slow (relative to a standard
> PIC programmer) but simple and tidy. To program the
> device, just connect 
> the FT232R to a host's
> USB port and drive the application with a WinXP
> application. The WinXP 
> app needs to know only how
> to program only ONE device.
> 
> Flames appreciated. Other ideas welcome.
> 
> --Bob
> -- 
> http://www.piclist.com PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
> 


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