Consider using Wouter's ZPL (Zero Pin Loader) project. You can download it = here: http://www.circuitcellar.com/flash2002/Honorable/M285.zip ZPL is a bootloader specifically designed to have a minimal external footprint. It operates by wiggling the MCRL line of the part via a serial port, which sends precisely timed runtime pulses whose length are measured by the bootloader code. So you can embed it into an existing project with little more than a transistor to wiggle MCLR. And this was specifically designed for the 18F family. Comes with a python based loader, circuit, and report describing the entire process. The problem with the Microchip loader, the Tiny bootloader, and others is that virtually all of them tie up the hardware serial port making it a challenge to use when you have a project that also needs that serial port. I have always preferred a loader with some form of bit banged serial communications such as Wouters Wloader, ZPL, and Frank Sergeant's Pikme because you can use any general purpose I/O pin instead of a specific pin interface. MCLR can be used as an input only input in virtually any modern PIC and it's almost always an out of the way pin. For example I'm working with 16F1938's at the moment and MCLR is shared with PORTE3, which is the only PORTE pin on the 28 pin part. Virtually useless for anything else, but a great dedicated pin for a bootloader. My current bootloader project is adding auto selecting bit rate code and reliability when using the internal oscillators. I find that the clock drifts due to temp changes enough that a consistent async connection is difficult to pull off with out an external cyrstal or resonator. My plan is to embed the clock signal and two bits of data into every async character sent. So even if the clock drifts, it'll autoadjust with each character sent. BAJ On Mon, Jun 27, 2011 at 09:31:08AM -0400, John Ferrell wrote: > On 6/25/2011 3:00 PM, Vicent Colomar Prats wrote: > > There are many diferent bootloaders for pic 18F. All them work the same= way, > > first time you burn it into flash via programmer, and then go with a se= rial > > communication(ex: usb to serial converter). > > > > In microchip link, it can sound complicated, but it is not. When you ha= ve > > first programmed then is exactly as easy and simple as any other micro = via > > bootloader thru a serial port. > > > > 2011/6/25 John Ferrell > > > >> I know there are many Google answers to this question but I > >> know that a current response on this list will provide a better > >> response than I am likely to pursue from Google. > >> > >> > >> I would like to add a bootloader to a project. I would like > >> to keep this task as simple as possible. I am using a PIC 18F4520. > >> Is the method at http://www.microchipc.com/PIC18bootload/ > >> > >> As good as any or is there a less complicated or otherwise better appr= oach? > >> > >> > >> A little tinkering with an AVR Butterfly has impressed me with the > >> usefulness of a bootloader. > >> Some AVR chips come from the factory with the bootloader installed. > >> > >> -- > >> > >> *John Ferrell W8CCW* > >> > >> ** > >> > >> *'A man's feet should be planted in his country, but his eyes should > >> survey the world. '* > >> > >> *George Santayana* > >> > >> ** > >> > >> -- > >> http://www.piclist.com PIC/SX FAQ& list archive > >> View/change your membership options at > >> http://mailman.mit.edu/mailman/listinfo/piclist > >> > Thank you, > I am having problems finding a way that works for me. I will continue to= =20 > dig deeper. >=20 > --=20 >=20 > *John Ferrell W8CCW* >=20 > ** >=20 > *'A man's feet should be planted in his country, but his eyes should=20 > survey the world. '* >=20 > *George Santayana* >=20 > ** >=20 > --=20 > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist --=20 Byron A. Jeff Department Chair: IT/CS/CNET College of Information and Mathematical Sciences Clayton State University http://cims.clayton.edu/bjeff --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .