[hpsdr] [OZY] Initial OZY Schematic Posted For Review and Comments - May 10, 2006

[Ahti Aintila]

Hello Phil,

I am not aware of any USB connector with integrated filters
(magnetics). There are combinations of RJ-45 and USB connectors, but
usually the "integrated magnetics" are for the RJ-45 connector only.

For suitable USB2.0 filter components see:
<http://www.tdk.co.jp/epuf/acm2012_e.pdf>

73, Ahti OH2RZ

On 11/05/06, Philip Covington <p.covington at gmail.com> wrote:
> Hi Lyle, Ahti,
>
> Thanks for the recommendations.  I will add those items/changes to the
> schematic.  I'll wait until tomorrow though to allow others to comment
> on the current state of the design.
>
> Lyle:
>
> I will go with the SN75C1406 and the MPC130 @ 2.7V (has internal 5 k
> pullup - is that ok?).  Will determine what to do about a RS-232
> connector when I get further on the pcb layout...  Any suggestions on
> what ATLAS bus line to use for RESET?
>
> Ahti:
>
> I have already set up routing constraints/rules for the D+/D- pair in
> the layout program per the Cypress TRM recommendations.  Any
> suggestions on a particular USB connector (integrated magnetics or
> no?).
>
>
> 73 de Phil N8VB
>
> On 5/10/06, Ahti Aintila <oh2rz.sdr at gmail.com> wrote:
> > Phil,
> >
> > The small inductor L1 from P1/pin4 to ground is useful for limiting
> > the ground loop currents, but C13 should be connected to P1/pin1
> > (+5V). C14 is unnecessary. Data lines from P1/pin2, pin3 to DMINUS and
> > DPLUS should have a small common mode choke and overvoltage clamps
> > like SN75240PW. Keep the PCB trace capacitance of the data lines small
> > and well balanced.
> >
> > 73, Ahti OH2RZ
> >
> >
> > On 10/05/06, Lyle Johnson <kk7p at wavecable.com> wrote:
> > > ***** High Performance Software Defined Radio Discussion List *****
> > >
> > > Hello Phil!
> > >
> > > > Please review and make comments.
> > > >
> > > > Some initial questions:
> > > >
> > > > 1.  Do we need external SRAM?  There are 26 RAM blocks of 4608 bits
> > > > (including parity) each in the Cyclone II EP2C5Q208C8 part that I am
> > > > using.  I can probably fit in a 128Kx8 (1Mb) SRAM but, if populated,
> > > > it will use up the 32 expansion IO lines that are left from the FPGA.
> > >
> > > I think no.  The FX2 is there primarily to act as a USB interface.
> > > Extra memory might be good for buffering, but then the host computer
> > > probably has lots of memory for that purpose.
> > >
> > > If we need a CPU in the HPSDR box with a lot of memory, we may want to
> > > just make a board that provides that, along with the IO we might want
> > > for local control, CAN bus, etc.  Perhaps an ARM or something similar.
> > >
> > > > 2. Are 8 optional SMT LEDs tied to the FPGA_GPIO[1-8] lines enough for
> > > > status/debugging use?  These would not be of much use if I add the
> > > > SRAM to those lines, so that is why I call them optional.
> > >
> > > Should be enough.
> > >
> > > ***
> > >
> > > I note that the async port lines come to a 4-pin header.  If there s
> > > room, I'd like to see these buffered to RS232 levels even if we can't
> > > fit a DE9 connector or pair of DE9 connectors to the board.  Almost
> > > anyone who uses these lines is going to have to buffer them, so we might
> > > as well do it.  We won't have charge pump noise since we have +/-12
> > > available.  An SN75C1406 is small, has enough lines,and is cheap.  If we
> > > lack space for a DE9, we could put in a 2x5 header that, with a
> > > pin-for-pin ribbon cable would result in the correct pin out for a DE9.
> > >
> > > Also, I wonder if the reset line should go to an ATLAS pin?  If we have
> > > several processor eventually installed, it might be good if they can
> > > come out of reset at roughly the same moment so we don;t have to write
> > > all sorts of code to get things sync'ed up.  A reset voltage monitor
> > > chip could eliminate threshold ambiguity, such as an MCP120 series part
> > > from Microchip.
> > >
> > > Finally, is it worth adding a physical reset button so we can bump it
> > > and wonder why the FX2 rebooted?
> > >
> > > 73,
> > >
> > > Lyle KK7P
> > >
> > > _______________________________________________
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> >
>

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