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Message
From: wesselin@n...<wesselin@n...>
Date: Wed May 5 12:10:05 CEST 2004
Subject: [usb] Oscillator
Hi,first of all you should have a source library with your fpga, mine was
something like virtex2.v or virtex2.vhdl. The DCM or your DLL should be
defined there as a black box for synthesis. You can either infer the DLL
with synthesis directives or instanciate the DCM (make a DCM instance
in your RTL code). Either way you need to add some synthesis
directives in your constraints file. Check the xilinx website there's plenty
of documentation.
i dont know whether the DLL will give you the 48 MHz, because it's
basically a primitive of the DCM so i don't know whether it has the same
options/features. Check it out yourself on the xilinx website.
Regards,
Egwin Wesselink.
----- Original Message -----
From: M. AbuKhater<perocletos@y...>
To:
Date: Tue May 4 15:33:41 CEST 2004
Subject: [usb] Oscillator
> Hi
> Actually I do have a DLL on the spartan, but the board comes with
> 100MHz oscillator, can I get a 48M out of this one.
> besides it seems I dont have the DCM, how can I get it, I have the
> ISE from Xilinx, can I access the DLL from this software?
> Regards
> Abukhater
> wesselin@n... wrote:
> Hi,
> i used a DCM (Digital clock manager) of a virtex II to double a
> clock
> frequency, but it can also div and mult frequency's. Check your
> spartan
> II data sheet or user guide, if you have a DLL or DCM you should be
> able
> to fiddle around with clocks to get your 48 MHz.
> Regards,
> Egwin Wesselink.
> ----- Original Message -----
> From: M. AbuKhater
>
> To:
> Date: Sun May 2 11:58:53 CEST 2004
> Subject: [usb] Oscillator
> > hello all
> > I was wondering where can I get a 48MHz oscillator, the
> available
> > one are 50 and 45. the FPGA board I am using has a dividable
> > 100MHz, so I can get 50 or 33.3 or 25 .... MHz. the USB1.1
> core
> > needs a 48MHz.
> > I brought a 48 MHz crystal, but the circuit with 74F04
> inverters is
> > not working on well, it seems the frequiency is so high.
> should I
> > try CMOS inverters or is there any better solution.
> > I know there is a DLL (or PLL) inside the Spartan II FPGA, can
> I
> > get a 48 M out of it?
> >
> > one more thing
> > what is the function of the following ports in the USB1.1
> core:
> >
> > Vendor_data<15:0>
> > ep_sel<3:0>
> > wIndex<15:0>
> > wVAlue<15:0>
> > v_set_feature:
> > v_set_int
> >
> > thanks in advance
> >
> > M. Abukhater
> >
> > ---------------------------------
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