[Gmecm] Any USB developers out there?

[Craig Moates]

Steve,

Ok, cool. That all sounds consistent then. Glad it's going! Maybe the xtal frequency needs to be accounted for appropriately in the 
PIC's fuse bit settings? Like a clock divisor for the USB bus? That'd be sweet if that's all it is.

I've been using Eagle 4.16 for pretty much everything. Some folks groan about it, but in my experience, everything has a downside. 
But it gets the job done and helps greatly when it comes to exchanging ideas and information.

If you'd like me to take a stab at revising the layout, I'd be happy to. I've done some work around trying to optimize the 68HC58 
incorporation. Here's one that I did:
http://www.moates.net/images/rr2/rr2_compare.jpg
Top right of leftmost picture. Been going to smaller 0402 components, they're sweet ;^).

Best regards,
Craig Moates


----- Original Message ----- 
From: "Steve Ravet" <Steve.Ravet at arm.com>
To: <gmecm at diy-efi.org>
Sent: Sunday, November 19, 2006 11:41 PM
Subject: RE: [Gmecm] Any USB developers out there?




> -----Original Message-----
> From: gmecm-bounces at diy-efi.org
> [mailto:gmecm-bounces at diy-efi.org] On Behalf Of Craig Moates
> Sent: Thursday, November 09, 2006 11:51 AM
> To: gmecm at diy-efi.org
> Subject: Re: [Gmecm] Any USB developers out there?
>
> Steve,
>
> Definitely check the crystal and capacitor areas. Those are
> ceramics you are using for the 18pF set? Check that it's set
> up for 18pf on the xtal desired capacitance?

The crystal is 20 MHz 18pf according to the digikey datasheet.  They're
ceramic caps.

I don't know what the problem with the crystal circuit is, but I removed
it and used a 4 MHz OSC instead, changing the firmware accordingly, and
now it works.  I tried with and without the load resistor (on the
crystal) but no change.  The demo board has an external load resistor
but the data sheet shows a resistor internal to the part.

I decided that I want USB power after all so I can reflash the PIC
without external power.  You mentioned the circuit you use but I can't
find the note now.  What is it?

Craig, what do you use for schematic capture and PCB layout?

Maybe there'll be a USB <-> VPW project working by Christmas now...

thanks for the suggestions everyone,

--steve

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