[Gmecm] Any USB developers out there?
Paul Smith
psmith
Fri Nov 10 00:47:42 UTC 2006
Hi Steve,
I had sent the foll to your email address thinking I would avoid polluting
the list but maybe it did not make it to you anyways here's a copy
Hi Steve,
I took a look at this last night, at first glance the USB traces seem OK,
did you check the code to make sure the internal pullups for D+ are
enabled?
FSEN & UPUEN =1
Also that the USB clock is running at 48Mhz?
Thanks
Paul
> Hi Craig, this app (USB to VPW converter) will always be connected to
> vehicle power so I'm not using the USB power option. VBUS (power from
> the USB cable) has a bypass capacitor to ground but that's it, and the
> circuit is always powered via VCC from the 5V regulator. That's not
> what the schematic shows but that's been changed on my PCB.
>
> --steve
>
>> -----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 3:31 PM
>> To: gmecm at diy-efi.org
>> Subject: Re: [Gmecm] Any USB developers out there?
>>
>> Not sure about the 2455, but could you be having Vcc and Vusb
>> contention? Two separate power supplies? With these low-power
>> circuits, I've typically allowed them to be USB bus-powered
>> in parallel with whatever target device power (OBD2 regulated
>> etc) through a pair of schottky diodes. That has always
>> worked well, you end up with 4.9v or thereabouts which is adequate.
>>
>> What you describe below could be consistent with this sort of
>> thing. Maybe just lift the Vusb and jumper it over from Vcc
>> to see what happens.
>>
>> Best regards,
>> Craig Moates
>>
>>
>>
>> ----- Original Message -----
>> From: "Steve Ravet" <Steve.Ravet at arm.com>
>> To: <gmecm at diy-efi.org>
>> Sent: Thursday, November 09, 2006 2:52 PM
>> Subject: RE: [Gmecm] Any USB developers out there?
>>
>>
>> Craig, thanks for the suggestions. I brought it in to work today and
>> found something interesting. When the board is powered up,
>> no USB cable
>> connected, the 20 MHz crystal oscillates fine. When I plug in the USB
>> cable the OSC gets distorted, then goes flat after about 1
>> sec. As soon
>> as I pull out the USB cable the OSC comes back. This is some kind of
>> loading issue? The PIC has some internal settings related to the OSC,
>> I'll have to double check them.
>>
>> thanks,
>> --steve
>>
>> > -----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?
>> >
>> > 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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