> You've hit upon a fundamental paradox if your goal is to create a USB PIC
> programmer using a PIC. To create the programmer, you have to program the
> PIC. But in order to program the PIC, you need a programmer. And if you g=
et
> a programmer, then there's no real need to build a programmer.

Well... well... i took this circuitous (pun intended) route ;-)
Way back in 2007, i made a clone of PicKit.
I now use the fsusb + bootloader to update the firmware and the process NOW=
 is trivial.

Q: Ok, How did you get the bootloader in ?=20
A: I used another 8051 based board i had made before.
 a PC "software" i wrote would stream the PIC-hex bootloader bytes over UAR=
T to the 8051.The custom firmware i wrote on 8051 would bit-bang the data t=
o PIC on its MOSI/MISO lines. The bootloader is the standard pickit bootloa=
der Microchip provides for PIC18F2455.

Q: Ok now how did you get the 8051 firmware into 8051 ?
A: Using parallel port of PC. (remember the clunky ol parallel port that us=
ed to be in PC circa 1990's ?)
 I wrote a program to "byte"-bang the 8051-hex data over parallel port. the=
 good old AT89C51 can be programmed in parallel mode.
 This 8051-hex was the PIC "programmer" which worked quite well.
 finally i decided that i have had enough fun and got around to do somethin=
g useful than writing bootloaders to load bootloaders ;-)

Q: are you a member of some fringe lunatic group ?
A: Heck no ! it was quite a bit of fun as i got things working by doing eve=
ry single thing that need to get a chip working; myself (as opposed to usin=
g a programmer which will magically program the firmware).
If you need to show results to your boss/yourself, use a programmer.
Time taken: more than 1 year.

Circa 2011: i can now program another PIC using my PicKit clone :-) . but o=
nly time i use this scheme is to program a bootloader or if bootloader goes=
 kaput.

-Mahesh


--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.