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Aide Scilab >> Xcos > palettes > Palette Sources > GENSQR_f


Square wave generator

Block Screenshot


This block is a square wave generator: output takes values -M and +M. Every time an event is received on the input event port, the output switches from -M to M, or M to -M.

Typically the event input port is used to specify the signal period.

Dialog box

  • Amplitude

    a scalar M.

    Properties : Type 'vec' of size 1.

Default properties

  • always active: no

  • direct-feedthrough: no

  • zero-crossing: no

  • mode: no

  • regular outputs:

    - port 1 : size [1,1] / type 1

  • number/sizes of activation inputs: 1

  • number/sizes of activation outputs: 0

  • continuous-time state: no

  • discrete-time state: yes

  • object discrete-time state: no

  • name of computational function: gensqr

Square wave generator: Example

This is a typical use of this block in context. This example should also alert the user about a specific behavior when linked to the same event its sink. Open this exemple into Xcos

First the sink block is a scope with a sample rate set to 1 second. This parameter will affect the printed results of all the diagram branches.

The first source block (green) illustrate the typical use of this block. The period of each output level is set with a clock. The signal edge is fast and should be accurate for most of the application with a edge speed ratio of 1/10.

The second source block (blue) illustrate a much more problematic use case. The signal edge is not as fast as the previous one and can lead problematic use case. Users can use these parameters to illustrate some limitations of a design.

The third source block (yellow) illustrate a mis-use and a common first user error. The block activation times are the same as the scope. The scope compute only one positve or negative M point at a and draw a line from (positive) to (negative).

Computational function

  • SCI/modules/scicos_blocks/src/fortran/gensqr.f (Type 0)


Ramine Nikoukhah - INRIA


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Last updated:
Wed Oct 05 12:11:03 CEST 2011