[Gmecm] Any USB developers out there?

[Craig Moates]

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?

I'd be possibly concerned with how the trace is run on that 1M there by the xtal. Could be some induced stuff going on? Also, 
doesn't the pic have the load built in?

Considered adding caps to gnd on the USB lines coming in? Could be picking up some noise, I like to put like some 47pF on there.

I assume you've tried even after a hard reset via your switch in there, right? Just wondering about brownout issues and that sort of 
thing.

Have you tried it with just the USB, PIC, xtal, and resonator/decoupling caps connected? Could help to step in slowly to see what's 
'not' causing the problem. I know I always get excited, assemble the whole thing, and then step back to find one trace or leg that 
isn't going where it should.

Best regards,
Craig Moates



----- Original Message ----- 
From: "Steve Ravet" <Steve.Ravet at arm.com>
To: <gmecm at diy-efi.org>
Sent: Monday, November 06, 2006 10:02 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 Paul Smith
> Sent: Monday, November 06, 2006 8:10 PM
> To: gmecm at diy-efi.org
> Subject: Re: [Gmecm] Any USB developers out there?
>
> I would'nt call myself a USB expert but would be willing to
> help if you do not get any other volunteers.
>
> I have worked a bit with the 18f2550 series that supports USB.
>
> Paul
>


Hi Paul.  I have uploaded the project to the TWiki page:

http://www.diy-efi.org/twiki/bin/view.pl/Gmecm/UsbVpw

I think the problem is in hardware instead of software.  I am testing
the board with a keyboard/mouse demo that is supposed to move the mouse
in a circle and send keystrokes.  This firmware works on the PIC demo
board that I bought, but it doesn't work on my PCB.  I ran usbview.exe
to see that most of the enumeration is correct except the last 4 items:

my board                              demo board
----------------------------------------------------------------
Current Config Value: 0x00            Current Config Value: 0x01
Device Bus Speed: Low                 Device Bus Speed: Full
Device Address: 0x00                  Device Address: 0x01
Open Pipes: 0                         Open Pipes: 1

That stuff is clear as mud to me.  The thing that stands out is the Bus
Speed.  I don't know why my PCB shows up as Low while the demo board is
Full.  I have checked the D- and D+ lines and the pullup is in the right
place.

I am using the PIC18F2455.  I posted to the microchip forums also and
got some suggestions but haven't found the answer yet.  That thread is
here:

http://forum.microchip.com/tm.aspx?m=185797

thanks for any help,

--steve
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