USB reset question

I have been observing unexpected USB resets in a product I am
troubleshooting.  The board has three USB devices internal to itself:  a 2.0
hub chip, a PIC18F4550 which I programmed, and a touch panel circuit.
Everything works fine until we attach another device to the hub - a
mouse-keyboard combination custom-designed for the overall product.  Then I
see all three USB devices (the PIC, the touch panel, and the mouse-keyboard)
are USB-reset every 2-5 minutes.

Reading through the spec and a couple of USB design books, it seems to me
that the USB reset is normally originated by the USB root/host computer.  Is
it reasonable that that computer would issue resets to devices?  Is it
possible that my hub chip is doing it on its own?

Check the current draw. It can not exceed 100ma.


"Richard Henry" <rphenry@home.com> wrote in message
news:3thk9hFstq5mU1@individual.net...
> I have been observing unexpected USB resets in a product I am
> troubleshooting.  The board has three USB devices internal to itself:  a
2.0
> hub chip, a PIC18F4550 which I programmed, and a touch panel circuit.
> Everything works fine until we attach another device to the hub - a
> mouse-keyboard combination custom-designed for the overall product.  Then
I
> see all three USB devices (the PIC, the touch panel, and the
mouse-keyboard)
> are USB-reset every 2-5 minutes.
>
> Reading through the spec and a couple of USB design books, it seems to me
> that the USB reset is normally originated by the USB root/host computer.
Is
> it reasonable that that computer would issue resets to devices?  Is it
> possible that my hub chip is doing it on its own?
>
>

"Jona Vark" <noemail@all.com> wrote in message
news:EuOcf.14850$tV6.1691@newssvr27.news.prodigy.net...
> Check the current draw. It can not exceed 100ma.

All the devices are self-powered, but that is worth checking.

> "Richard Henry" <rphenry@home.com> wrote in message
> news:3thk9hFstq5mU1@individual.net...
> > I have been observing unexpected USB resets in a product I am
> > troubleshooting.  The board has three USB devices internal to itself:  a
> 2.0
> > hub chip, a PIC18F4550 which I programmed, and a touch panel circuit.
> > Everything works fine until we attach another device to the hub - a
> > mouse-keyboard combination custom-designed for the overall product.
Then
> I
> > see all three USB devices (the PIC, the touch panel, and the
> mouse-keyboard)
> > are USB-reset every 2-5 minutes.
> >
> > Reading through the spec and a couple of USB design books, it seems to
me
> > that the USB reset is normally originated by the USB root/host computer.
> Is
> > it reasonable that that computer would issue resets to devices?  Is it
> > possible that my hub chip is doing it on its own?
> >
> >
>
>