On Tue, Jul 17, 2001 at 12:34:14PM +1000, Antonio L Benci wrote:
> Check out:
>
>         http://www.dontronics.com/rfarmer.html

Just a real quick comment or two from looking at the site:

- I have a problem with the fact that it uses the standard USART. That's a
  valuable piece of real estate to dedicate to the bootloader.
- Because it uses the standard USART it requires the addition of serial port
  conversion hardware on board the target.
- It adds a 15 second boot delay to the system. Just a bit too invasive for
  my taste.
- It requires the programmer to move the code out of the reset area instead of
  moving it automatically.

I'm absolutely a true fan of Wloader:

- Instead of the USART, Wloader uses a single I/O pin for it's bit banged
  serial interface.
- The hardware added to the target is only two pullup resistors. Everything
  else can be placed on the programming dongle.
- Instant boot because the pullup resistor on the serial I/O pin indicates
  instantly if the programming dongle is connected to the target. The
  bootloader automatically starts if the dongle is connected.
- Wloader automatically moves the reset vector code so that the loader is
  completely transparent to the development system.
- The wloader serial port can be used as a debugging serial port after the
  application starts.
- Finally the programming dongle consist of 3 resistors and a zener diode
  in its simplest form. A dongle can be wired on a breadboard in about 5
  minutes with a buck worth of common parts. It's totally awesome when the
  auto reset circuit is added to the dongle. It consists of a transistor,
  diode, and a couple of more resistors.

Wloader is unobtrusive to both the hardware and the software of the target.
Secondly it's simple to build and simple to use. That's the two primary
goals of a bootloader in my mind.

In keeping with the simplicity of the system I have a single chip programmer
that programs 16F87X PICs in low voltage mode. It's just a modified Tait
programmer, and it's only purpose for me is to stick Wloader on the chip.

You can find my PIC page here:

http://www.finitesite.com/d3jsys

BAJ
>
> Cheers...
>
> wouter van ooijen & floortje hanneman wrote:
> >
> > > 1. I understand the idea of a bootloader, can someone with experience in
> > > that area please supply me some info on implementing a bootloader section
> > > for f873/f877 or point me in good direction.
> >
> > http://www.xs4all.nl/~wf/wouter/pic/wloader
> > and of course the f877 datasheet (real men don't need any other
> > documentation)
> > btw did you check techref?
> >
> > Wouter
>
> Nino.

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