Generating square wave using an embeded matlab function

Question

Seyedfoad Taghizadeh 2014-1-21

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/113069-generating-square-wave-using-an-embeded-matlab-function

评论： huynh quyen 2016-8-19

采纳的回答： Walter Roberson

在 MATLAB Online 中打开

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.

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Azzi Abdelmalek 2014-1-21

Sayedfoad, I suppose that you are accepting answers randomly.

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Walter Roberson 2014-1-21

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/113069-generating-square-wave-using-an-embeded-matlab-function#answer_121599

Your function is fine. You are not zoomed in enough to see the wave transitions.

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

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.

请先登录，再进行评论。

Answer 2

Azzi Abdelmalek 2014-1-21

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/113069-generating-square-wave-using-an-embeded-matlab-function#answer_121604

编辑：Azzi Abdelmalek 2014-1-21

在 MATLAB Online 中打开

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;

5 个评论
显示 3更早的评论隐藏 3更早的评论

Seyedfoad Taghizadeh 2014-1-22

Thanks alot, I used the block and it worked.

Regards Foad

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.

请先登录，再进行评论。