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Custom design for FMCOMMS1

Question asked by Mr.BLECK on Jul 25, 2013
Latest reply on Jan 7, 2014 by rmm92vt

Hi everyone,


I could not live with the reference design for a simple reason, XPS. So I left the microblaze module along with the IIC programming link, and inserted it as a sub module in an ISE project.


I wrote a simple DAC and ADC HDL modules for interfacing and use the given SDK codes for progrmming the PIC.


For the first trail, the ADC input data looks wrong I believe it is from timing problems. I checked for the solution in the FMCOMMS1 refernce design and I guess you worked arround this part by using an IODELAY whereby the software controls the dely value.


Couple of questions:


0- Is there a problem running the software Standalone without the ADC/DAC interfacing?

1- How does the IODELAY determine the correct value?

2- Why is the Constranit for OFFSET IN commented with: " cant use real numbers as bufg exceeds 4ns".?

In my understandings, one have to solve the timing problems either by delays the data w.r.t clock using the IODELAY; or the clock w.r.t the data using an MMCM?