DCM Core cannot generate output

[uche]

Hello All,

I have instantiated a DCM core with an input frequency of 32 MHz clock
signal from the device. I would like to recieve a 96 MHz output signal
from the DCM core, so I set the .xwa file to multiply the incomming
signal by 3. When I generate the bit stream and run the design on my
board, the FX pin doesn't seem to produce a frequency. I know I am
doing something incorrectly here, do I have to reset the DCM core, or
use another signal from the DCM core to obtain my desired output or
whatever ... please help.

Thanks,

 

[d_s_klein]

Hello All,

I have instantiated a DCM core with an input frequency of 32 MHz clock
signal from the device. I would like to recieve a 96 MHz output signal
from the DCM core, so I set the .xwa file to multiply the incomming
signal by 3. When I generate the bit stream and run the design on my
board, the FX pin doesn't seem to produce a frequency. I know I am
doing something incorrectly here, do I have to reset the DCM core, or
use another signal from the DCM core to obtain my desired output or
whatever ... please help.

Thanks,

Step one: Post to proper group (eg comp.arch.fpga)

When you post there, include the chip type you're trying to put a DCM
into.

If this is your "first time ever" working with DCM's, you might make
more progress working in schematic mode rather than HDL mode. Might.

RK

 

[naliali]

What is the FPGA you are using?
How do you know FX clock doesn't work? you can check it by a simple
counter running at ClkFX domain, and comparing it by another counter
running at Clk0 domain(offcourse if you have an interface to read the
results!). does Clk0 output of DCM works properly?
if yes then the following facts may cause this problem.
in the FPGAs the input signal to DCM must be greater than an specific
frequency unless the internal DLL can't lock. it depends on the
generation of FPGA you are using, for wxample in virtex-4 devices the
minimum input frequency is 32 M. Also there is an attribute for
setting working mode of internal DLL of DCM, named
"DLL_FREQUENCY_MODE", setting it "High" or "Low" changes the
limitation for input and output frequencies. if DCM sets to work on
LOW mode and FX clock becomes more than maximum allowable frequency in
the LOW mode, FX will not work. chek these parameters for your device.

good luck
Ali Noroozi