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Altera_Forum's avatar
Altera_Forum
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17 years ago

DE2 PLL Phase Shift Problem, Pase Shifting is not viewable

Hey People, I have been using the DE2 board for a while now with the nios processors and my own designs.

I was wondering if anyone could help me with this PLL Problem.

I have a one PLL with 3 stepped up outputs (c2 .. 0) at 200 MhZ each. I want a pase shift to be present on each and have done so in the megafunctions wizard and this is its output.

http://img137.imageshack.us/img137/875/altpll0wave0du9.jpg

I have since divided this down and tried to view any phase shift in the (c2 .. 0) on my CRO and there is none, i then divided it down further and connected the outputs to some LED's on the DE2 Board (Divided down to 0.5Hz or once every 2 Seconds) so i could see if there was any and if my CRO was stuffed.

Yet this was not successfull

Does anyone have any suggestions or can tell me what i am doing wrong. To divide the clock i am using D-FlipFlops

In the Simulator it simulates fine in functional, and the timing analysis dows show the phase shift.

I am using the Quartus II v6.1 Free Web Edition.

The project compiles with no errors and 7 warnings as follows.

Here is an example of the PLL and D-FF that i am using to divide the clock in a Daisy Chain Config

http://img237.imageshack.us/img237/7996/setupzx0.jpg

Here are the warning messages from compilation.

Warning: Using design file /altpll0.vhd, which is not specified as a design file for the current project, but contains definitions for 2 design units and 1 entities in project

Info: Found design unit 1: altpll0-SYN

Info: Found entity 1: altpll0

Warning: Output pins are stuck at VCC or GND

Warning: Pin "Control" stuck at VCC

Info: Quartus II Analysis & Synthesis was successful. 0 errors, 3 warnings

Info: Allocated 136 megabytes of memory during processing

Info: Processing ended: Mon Jul 14 21:09:42 2008

Info: Elapsed time: 00:00:02

Info: *******************************************************************

Info: Running Quartus II Partition Merge

Info: Version 6.1 Build 201 11/27/2006 SJ Web Edition

Info: Processing started: Mon Jul 14 21:09:44 2008

Info: Command: quartus_cdb --read_settings_files=off --write_settings_files=off KLR -c KLR --merge=on

Info: Using synthesis netlist for partition "Top"

Info: Netlist merging resolved 1 partition(s) out of the 1 partition(s) found

Info: Quartus II Partition Merge was successful. 0 errors, 0 warnings

Info: Allocated 95 megabytes of memory during processing

Info: Processing ended: Mon Jul 14 21:09:44 2008

Info: Elapsed time: 00:00:00

Info: *******************************************************************

Warning: Found 7 output pins without output pin load capacitance assignment

Info: Pin "COut2" has no specified output pin load capacitance -- assuming default load capacitance of 0 pF for timing analysis

Info: Pin "Control" has no specified output pin load capacitance -- assuming default load capacitance of 0 pF for timing analysis

Info: Pin "COut1" has no specified output pin load capacitance -- assuming default load capacitance of 0 pF for timing analysis

Info: Pin "COut0" has no specified output pin load capacitance -- assuming default load capacitance of 0 pF for timing analysis

Info: Pin "Test_1" has no specified output pin load capacitance -- assuming default load capacitance of 0 pF for timing analysis

Info: Pin "Test_2" has no specified output pin load capacitance -- assuming default load capacitance of 0 pF for timing analysis

Info: Pin "Test_3" has no specified output pin load capacitance -- assuming default load capacitance of 0 pF for timing analysis

Warning: Following 1 pins have nothing, GND, or VCC driving datain port -- changes to this connectivity may change fitting results

Info: Pin Control has VCC driving its datain port

Info: Quartus II Fitter was successful. 0 errors, 2 warnings

Info: Allocated 222 megabytes of memory during processing

Info: Processing ended: Mon Jul 14 21:10:03 2008

Info: Elapsed time: 00:00:18

Info: Quartus II Assembler was successful. 0 errors, 0 warnings

Info: Allocated 176 megabytes of memory during processing

Info: Processing ended: Mon Jul 14 21:10:21 2008

Info: Elapsed time: 00:00:16

Info: *******************************************************************

Warning: Clock latency analysis for PLL offsets is supported for the current device family, but is not enabled

Warning: Found 84 node(s) in clock paths which may be acting as ripple and/or gated clocks -- node(s) analyzed as buffer(s) resulting in clock skew

Info: Detected ripple clock "inst15" as buffer

Info: Detected ripple clock "inst17" as buffer

Info: Detected ripple clock "inst30" as buffer

**** .... More Lines Like this .... ****

Info: Detected ripple clock "inst555" as buffer

Info: Detected ripple clock "inst556" as buffer

Info: Detected ripple clock "inst557" as buffer

Info: Quartus II Classic Timing Analyzer was successful. 0 errors, 2 warnings

Info: Allocated 102 megabytes of memory during processing

Info: Processing ended: Mon Jul 14 21:10:23 2008

Info: Elapsed time: 00:00:01

Info: Quartus II Full Compilation was successful. 0 errors, 7 warnings

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor

    The warnings aren't related to PLL operation in general, they can be ignored regarding phase shift.

    I would expect, that the phase shift is implemented as shown in the schematic symbol, however, the actual PLL parameters can be reviewed in compilation report under fitter/ resource section/PLL. I can't see how the phase shift can be vizualized by dividing the clock, cause this operation doesn't increase the ns scale of the phase shift. But it would be detectable with a fast multichannel oscilloscope.
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor

    Hmm, thanks for the tip. I have an idea how to test it, Ill let you know what i find.

    as for my CRO it is capable of seeing the phase shifts i am trying to acheive.

    regards

    RSTEP