Re: [RFC] USB driver for talking to the Microchip PIC18 boot loader

[mgross <640e9920@gmail.com>]

On Sun, Dec 30, 2007 at 10:40:45AM +0800, Xiaofan Chen wrote:
> On Dec 30, 2007 6:15 AM, Alan Stern <stern@rowland.harvard.edu> wrote:
> > On Sat, 29 Dec 2007, mgross wrote:
> >
> > > I'm playing around with a PIC based project at home (not an Intel
> > > activity) and found I needed a usb driver to talk to the boot loader
> > > so I can program my USB Bitwhacker with new custom firmware.  The
> > > following adds the pic18bl driver to the kernel.  Its pretty simple
> > > and is somewhat based on bits of a libusb driver that does some of
> > > what this driver does.
> > >
> > > What do you think?
> >
> > Not to detract from your driver, but would it be possible to do the
> > whole thing in userspace using libusb?  Maybe by extending the driver
> > you mentioned?
> >
> 
> The existing libusb based application works fine for PICDEM FS USB
> or those based on it (like the Bitwhacker the OP is using).

The device ID's are different 0x000C in ldusb.c vrs 0x000b in the
driver I just posted.

Have you read my patch yet?

> 
> Please do not add it to the kernel. There are libusb based application
> for both the bootloader and the demo application and both are working
> fine under Linux (along with Windows and I am trying to get FreeBSD
> working).

The libusb based FW loader http://www.internetking.org/fsusb/ program
is nasty and didn't work on one of my systems, so I refactored it into
a kernel driver and python program.

> 
> Last time the demo application has been added to the ldusb and
> I think it is not a good idea. But since then I've added patches to
> the existing libusb application.
> 
> Relevant discussion in thread
> '[PATCH 70/78] USB: add picdem device to ldusb'
> http://marc.info/?t=117770076400003&r=1&w=2
> 
> So please do not do this again. It is not a problem for the libusb
> based applications after the patches but it is really not necessary.

Why not?

There are a lot of redundant things in the world.  Linux is not
necessary if you really want to take this argument to its extreme.

> 
> Original libusb based application for the bootloader:
> http://www.internetking.org/fsusb/

Yup thats the code.  I found it way complex to read and felt a simple
kernel driver and simple python program much nicer to my
sensibilities.

We are getting quickly getting into a fuzzy/ opinion, area on this
thread.  Is there a technical angle we can discuss?  My LOC count of
the kernel driver and boot loader is smaller than the fsusb thing.
Also, with a kernel driver and a python lib, a GUI based boot loader
utility can be had with little effort.
 
> Original libusb based application for the Demo which
> also includes my patch for libusb-win32.
> http://www.varxec.net/picdem_fs_usb/
> 
> Updated Patches to detach the kernel driver for both
> the bootloader and Demo application.
> http://forum.microchip.com/tm.aspx?m=106426
> 
> Xiaofan Chen
> http://mcuee.blogspot.com

You blogging about me already?
I wont comment on that.

--mgross


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