Generating square wave using an embeded matlab function

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Seyedfoad Taghizadeh
评论： huynh quyen 2016-8-19
Hi,
I intend to generate a square wave which is applied on a DSP.
I have written these codes and put them in an embeded Matlab function.
function y = fcn(u)
%#eml
t=0:0.001:1
h = sign(sin(125600*t+u));
y= (h+1)/2
where, u is a constant value of 0.582 which is used for shifting the square wave.
The problem is at the out put in the simulation, instead of getting a square wave, I see only two straight lines of y=o and y=1.
Please let me know where is the problem that I can not get the square wave?
Note that the frequency of square wave must be 20 kHz. Therefore, I adjust the sampling time as 1e-7 s. And also its amplitude is between 0 and 1 In addition, due to this signal must be transferred to a DSP board, in the "solver option" I chose the type: " Fixed-step" and for the Solver: "Discrete (no continues state)".
Thanks a lot.

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采纳的回答

Walter Roberson
Walter Roberson 2014-1-21
Your function is fine. You are not zoomed in enough to see the wave transitions.
  1 个评论
Seyedfoad Taghizadeh
Seyedfoad Taghizadeh 2014-1-21
Thanks a lot for your reply, Actually, when I zoom in I can not see the output. Even when I convert this system using a compiler on a DSP board, it is compiled completely, but I can not see the waveform on Oscilloscope as well.
Please let me know if there is a solution.

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更多回答（1 个）

Azzi Abdelmalek
Azzi Abdelmalek 2014-1-21
编辑：Azzi Abdelmalek 2014-1-21
Seyedfoad, You can't define the time inside the Embedded function, you can notice that your output y is not a scalar, but a vector with length equal to numel(0:0.001:1). The two lines you are seeing, are the 51 output of your embedded function that are equal to 1 for some of them and 0 for the others, you can check this by using a [to workspace] block.
But the question is, why not to just use a pulse generator block?
You can use an embedded function with an input signal t coming from a clock block. and the code is the same as yours without the vector time
function y = fcn(t)
u=0.582;
h = sign(sin(125600*t+u));
y= (h+1)/2;
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huynh quyen
huynh quyen 2016-8-19
dear Foad, I want to generate 40khz pulse wave on raspberry pi , I used your block as the figure following but not accurately, simulation is display precisely but when I measure on ocsiloscope is wrong display. Please, help me.

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