In Simulink ,the pn sequence generator(essential blk) in frame based mode s not being accepted by the hdl converter. But the output of the pn sequence generator is given to a serial to parallel converter. What cud b the alternative for this?

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Accepted Answer

Bharath Venkataraman
Bharath Venkataraman on 20 Feb 2014
Please check to see if the inputs are constants. If so, change the sample time on the constant block to be 1 or some such value.
One other thing you can do for your initial question is to get values to the PN sequence genrator serially, and take the output to a tap delay line from which you can get a list of multiple values. To ensure you get non-repeated values, you can use a downsample block right after the tap delay. Putting a uni delay block after the downsample genrates more efficient HDL code.
For a set of 10 values, PN Sequence (serial) -> Tap Delay (10) -> Downsample (10) -> Unit Delay

More Answers (3)

Tim McBrayer
Tim McBrayer on 20 Feb 2014
Frame based models are not supported by HDL Coder. You will need to convert your design to a sample based format. Frames can exist outside the portion of design being converted to HDL code, if necessary.
  1 Comment
sin
sin on 20 Feb 2014
so instead of an inbuilt psuedorandom generator, we used a matlab function block. An error msg saying "system objects cannot be supported when the inputs have constant sample time" popped up while trying to convert the simulink to hdl. What does that error mean?

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sin
sin on 21 Feb 2014
Hey thanks for the reply, but if we connect pn sequence to tap delay-> downsample->unit delay as u said all the outputs appear 0. And using matlab function block instead of pnseq block generates error such as" unsupported system objects" or " cannot use system objects when all the inputs have constant sample time". These errors appear during hdl conversion.
Thnaks in Advance

sin
sin on 24 Feb 2014
Pls help . its urgent some unsupported loop problem in matlab function block in simulink. even though the output of the previous block displays only single vector of output, the matlab function displays more than one input vector. coz of this , its not getting converted using hdl converter. it would be great if some one can help.
thanks in advance

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