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Participant
Participant
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Registered: ‎03-29-2013

Calibration stucks at WAIT_FOR_OUDONE for SLX45T + 4-Gbit DDR3 DRAM

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Hello!

 

My custom PCB cannot complete calibration. The beginning of my story is https://forums.xilinx.com/t5/Spartan-Family-FPGAs/Hardware-Calibration-Fail-for-SLX45T-4-Gbit-DDR3-DRAM/td-p/779155

 

I've just performed X-Ray scan of my PCB and there are no soldering problems.

CK/#CK arrives after DQS/#DQS (about 70 ps margin or more).

 

Calibration stops on WAIT_FOR_OUDONE stage forever (waiting MCB_UODONECAL).

 

The important sign of the current fault - there is no activity on LDQS/#LDQS and UDQS/#UDQS lines. MCB hardware calibration should involve those signals into the calibration process (I see it on my previous board).

Unfortunately, these signals go from blackboxed MCB and IODRP2, so I can't check what's wrong.

It looks like hardware calibration does not really begins (as we see no attempts to put anything to xDQS).

 

Maybe Xilinx employees could give some ideas about that "stucked" MCB mode?

 

Many thanks for any help!

With regards,

Maksim

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Participant
Participant
4,355 Views
Registered: ‎03-29-2013

The reason is wrong resistor on CAS pin, so there was constant high level on the DRAM chip pin. All the DQS signals were also dropped because of it. It is necessary to use high-speed oscilloscope to check those waveforms.

Thanks for help.

View solution in original post

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Highlighted
Participant
Participant
4,356 Views
Registered: ‎03-29-2013

The reason is wrong resistor on CAS pin, so there was constant high level on the DRAM chip pin. All the DQS signals were also dropped because of it. It is necessary to use high-speed oscilloscope to check those waveforms.

Thanks for help.

View solution in original post

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