I would like to say, one for easy of use, and one for reliability. Our bootloaders support both entry method too: you can use a hardware signal to trigger bootloader mode, or you can have the embedded application software developed and use the "Reset PIC" push button on the bootloader program force the chip enter bootloader mode. Here is a bootloader ( with encryption capability) application note for the hot SAE-J1939 simulator product: http://www.auelectronics.com/UserManual-Au_PICBootloader.htm Regards, Funny N. Au Group Electronics, New Bedford, MA, http://www.AuElectronics.com ----- Original Message ---- From: Wouter van Ooijen To: Microcontroller discussion list - Public. Sent: Tuesday, May 6, 2008 9:16:33 AM Subject: Re: [PIC] another bootloader question >> I've seen it stated by some that you set a jumper or something that the >> code checks on power cycle to then branch to execute this code, but what >> about doing it in just firmware over the serial link? > > PICkit 2 provides both method, you can either use a switch or send a > command (over USB link) to get into the bootloader mode. And now for the $$$ question: *why* does pickit2 offer both methods? (sorry, switch off interactive teacher mode, switch on instruction mode) The main point with any bootloader is: can you trust the application to jield control to the bootloader? In most cases you can't, so you need a 'hardware' method to activate the bootloader. -- Wouter van Ooijen -- ------------------------------------------- Van Ooijen Technische Informatica: www.voti.nl consultancy, development, PICmicro products docent Hogeschool van Utrecht: www.voti.nl/hvu -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist ____________________________________________________________________________________ Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist