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Explorer
Explorer
5,811 Views
Registered: ‎11-21-2014

What can cause command issued to MCB not to be executed?

I am using MIG from Xilinx to write to DDR3 interfaced to Spartan6.

I am first wrote 64 bit data to the write FIFO of MCB to depth of 64. Then I drove following signals:

cmd_en = 1

cmd_instr = 0 --for write instruction

cmd_bl = 63 --for burst length of 64

 

I had following signals during that time interval(when cmd_en = 1 was issued).

cmd_full = 0

cmd_empty = 1

wr_en = 0

wr_mask = 0

wr_full = 1

wr_empty = 0.

 

In next clock, cmd_empty went low (=0). Other signals never changed even after very long simulation.

What can cause the MCB to not respond to my commands? (in MCB, mcb_command = 7, mcb_enable1 = 1, mcb_enable2= 1).

 

Please help.

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2 Replies
Instructor
Instructor
5,802 Views
Registered: ‎08-14-2007

Re: What can cause command issued to MCB not to be executed?

This could happen if the MCB hasn't completed calibration yet, or if there was an error.  There are a couple of error status outputs of the MCB you could check.

-- Gabor
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Explorer
Explorer
5,800 Views
Registered: ‎11-21-2014

Re: What can cause command issued to MCB not to be executed?

@gszakacs. Thanks for your answer. I have checked for calib_done before writing to FIFO and issuing the command. And I also check rd_error, wr_error, wr_underrun and rd_overflow signals. All those signals are low.

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