gnupic: DIY USB programmer ?
Subject:
Re: DIY USB programmer ?
From:
Manuel Bessler ####@####.####
Date:
6 Jan 2005 04:07:47 +0000
Message-Id: <20050106045958.D27123@betazed3.varxec.de>
Hi David,
On Wed, Jan 05, 2005 at 12:13:17PM -0500, David Willmore wrote:
>
> But the max values aren't the catch with those guys. From the experiences
> of some friends of mine who tried that it seems that the windows driver
> has a few 'gotchas'. Here's a common task for speaking to a PIC when
> you're programming it:
> set data line <wait> assert clock <wait> deassert clok <wait> next bit....
>
> Fine, you say, those <waits> can be as long as they want. Sure, they
> can, but that's not what you run into. The FTDI windows driver *caches*
> things you send to it and only updates the chip (over the USB) some 8000
> times a second. If you say "do something" and wait a little bit and
> then say "do something else", there is no guarentee that those two
> somethings will be sequenced when they hit the chip--they may hit the
> chip simultaniously--violating setup times for data->clock. So, I find
> these chips to be useless for this task. Blink a LED with a pin, yeah,
> they can do that, but something with delicate timing? No.
Hmm. I'd think that this shouldn't be a problem with those adaptor
cables, esp. the USB-to-parallel ones. If you talk to a printer via such
a cable, and packet/bytes get sequenced wrong, you might end up having
reversed/missing chars/lines in your printout... ??
> The thing that I feel makes it a good solution is that the programmer
> isn't all that 'intelligent'. I really want to resist the temptation
> to make it really 'intelligent'. For that way lies specialization
> and that doesn't buy me--as a programmer--much. Sure, if I was making
> some very specific tool for quickly programming chips and it had to
> do it as fast as possible, sure. But for a hobbiest or more casual
> professional designer, a few seconds is no huge issue. Especially if
> it ends up being able to program more chips. :)
Agree :)
I think your programmer could make a good substitute for hobbyists in
post-RS232 times. (as much as I hate to see RS232 go)
> > And the new USB flash PICs would be a great way for this. I even have
> > two 18F2550's here :)
>
> :) Oww, looks like you just offered to be a tester. :)
Well, if you have something ready, tell me and I'll setup something for
testing.
> > > To the computer, it will look like an USB->RS232 'dongle', so most
> >
> > This is even better. Excellent idea. I'm looking forward to your design.
> > Will it be free/open source ?
>
> With all of the work Craig, Alain, and Scott have done for all of us,
> could I honestly *not* make it open?
good thinking :)
I'd be great to have a gnupic PIC programmer...
If the design gets wider acceptance, then more of the programmer
softwares (pikdev,ic-prog,...) will adopt support for it.
Your design might be an option for those of my users that order pre-made
pcbs of my project from me. Then it would'n't make a big difference in
shipping. Of course, those who etch their own boards, buy PICs locally,..
they need the non-intelligent bootloader PIC programmer.
> > Please keep me posted on your programmer project.
>
> Sure will. I should probably set up a mailing list for interested
> people.
yep.
Manuel
--
Opensource/Free Software: No Gates, No Windows
