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'[PIC]: USB bootloader exists?'
2003\02\13@193914 by Ned Konz

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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

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2003\02\14@124422 by Harold Hallikainen

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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 <spam_OUTnedTakeThisOuTspamBIKE-NOMAD.COM> 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

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