I don't really see any problem with using the FTDI chip with a boot loader. As I recall, FTDI supplies a driver for Windoze so the device on the USB looks like another serial port. The boot loader software (including that in Microchip AN851) should be able to talk to it, not knowing the difference. AN851 has an interesting way of determining whether you're running the application or the loader. They use the last eeprom location as a flag. If that location contains 0xff, you stay in the boot loader. Anything else in that location and the boot loader dumps you into your PIC application. I'm still getting AN851 to work on my 18F6720 application, so I can't comment too much on it yet. However, I plan on changing the boot loader so on reset we go into the boot loader which sends a prompt to the outside PC. If the PC does not respond with something indicating it wants to boot load within a second or so, the boot loader exits and runs the main application. That's what I have in mind, anyway. Good luck! Harold ---------- Ned Konz writes: I'm considering making a unit using an 18F452 and a FTDI USB chip (either the 232 or the 245, I'm not sure which). One of the FTDI chips has a serial interface, the other has a bidirectional FIFO with a parallel interface. Has anyone used these chips with a bootloader? Any comments on its effectiveness? I see a couple of serial bootloaders for this chip, including one in an app note from Microchip, and also ones from: Martin Dubuc (derivative of the Microchip one): http://members.rogers.com/martin.dubuc/Bootloader/ Shane Tolmie's doesn't appear to have any source: http://www.microchipc.com/PIC18bootload Ideas? I'd also like to be able to use the same interface to talk to the PIC during normal operation, so there must be some way to dynamically vector to the bootloader (and, I suppose, the bootloader must be in series with the received-character interrupt, or the interrupt handler will have to notify the loader when in bootloader mode). Thanks, -- Ned Konz http://bike-nomad.com GPG key ID: BEEA7EFE - ________________________________________________________________ Sign Up for Juno Platinum Internet Access Today Only $9.95 per month! Visit www.juno.com -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body