Ho we run a section code one time in Matlab function block ? In below body I dont want assigning zeros in Dout after 1st iteration. This matlab function block run 100 times and problem is it every time set zeros in dout.

function y = ADC(u, clk, count)
%function y = fcn(u, clk)

count=count+1;
% if clk==1
%     disp('hello');
% end
% emulation of SAR ADC operation
Nbit = 7; 
Vref = 64;
VCM = Vref/2;
%dVin = (-37298:37299)/37299*Vref;
Point=u;
dVin = (-Point:Point)/Point*Vref;
%plot(dVin);
Vip = dVin/2+VCM;
Vin = -dVin/2+VCM;
N = length(dVin);
k=count;

*Dout = zeros(1,N);
B = zeros(1,Nbit);*

   while k <=N          
          if clk==1
              Vxp = Vip(k);
              Vxn = Vin(k);
              for kbit = 1:Nbit
                  if Vxp - Vxn > 0
                      B(kbit) = 1;
                      Vxp = Vxp - Vref*2^(-kbit);
                  else
                      B(kbit) = 0;
                      Vxn = Vxn - Vref*2^(-kbit);
                  end
              end
              Dout(k) = B(1)*64 + B(2)*32 + B(3)*16 + B(4)*8 + B(5)*4 + B(6)*2 + B(7)*1 -64 +0.5;
            %  k=k+1;

             break;

          else
             %k=k+1;
             break
          end

      end

plot(dVin,Dout,'r*')
y = Dout;

Answer 1

[Honglei Chen]

You can make Dout persistent so it preserves the value between runs, like this

persistent Dout;
if isempty(Dout)
  Dout = zeros(1,N);
end

HTH

[Sarfaraz Ahmed]

Yes. It's working. Thanks alot Honglei Chen. But, there is another problem that " Dout= [1x1001 double] Number of elements too large (>200) to display symbol value in tooltip". How can I resolve this problem ? Also in simulink "display" is yellow as showing error. I attached a snap. How can I resolve this problem ?

Thanks

[Honglei Chen]

This is an expected error as display cannot display more than 200 elements. If you want to see more info, you can either use a To Workspace block instead to send results to MATLAB or use a scope to plot the result.

HTH

[Sarfaraz Ahmed]

Thanks Honglei Chen. one more thing is that I am doing sampling of analog signal and simply in m file its running well but when I use matlab function it shows an error "Function 'stem' not supported for code generation." when I omit stem command it says "Variable 'x1' is not fully defined on some execution paths." here is my code "

function y  = sample(clk1)
% Sampling input signal

fs=500e3; %Very high sampling rate 500 kHz
f=10e3; %Frequency of sinusoid
nCyl=5; %generate five cycles of sinusoid
t=0:1/fs:nCyl*1/f; %time index
x=sin(2*pi*f*t);

plot(t,x)
title('Continuous sinusoidal signal');
xlabel('Time(s)');
ylabel('Amplitude');

if clk1==1
    fs1=50e3; %50kHz sampling rate
    t1=0:1/fs1:nCyl*1/f; %time index
    x1=sin(2*pi*f*t1);
    subplot(2,1,1);
    plot(t,x);
    hold on;
    stem(t1,x1);
end
y=x1;

[Walter Roberson]

MATLAB has no reason to know that clk1 will always equal to 1, so it has no reason to know that the assignment to x1 you do inside the "if" will always be done.

Though if clk1 will always equal to 1, then why bother to test it?

[Sarfaraz Ahmed]

Thank you.

clk1 will not always be equal to 1. it changes from 1 to 0 as well. and then 0 to 1 and so on. I dont know why stem is not working in matlab function block. is there any special reason of it even its working in simple m file ?

I declare x1 as persistent also I changes my code and now it rewrite every time on y. why its rewrite on every iteration ? could you please help it . Thanks

fs1=50e3; %50kHz sampling rate
t1=0:1/fs1:nCyl*1/f; %time index

if clk1==1 
    while k<=length(t1)
        x1=sin(2*pi*f*t1(k));
        k=k+1;
        break;
  %  stem(t1,x1);
    end
end

y=x1;

[Walter Roberson]

You are overwriting x1 each time through the while loop in the above code. You also have not initialized k before it is tested. Your previous version looked more likely.

You have not defined what should be assigned to x1 in the case that clk1 is not 1.

MATLAB Function Blocks are compiled except when acceleration mode is completely off. With the first level of acceleration that is possible, the compilation is to a form that can access basic MATLAB if some special steps are taken to declare access to MATLAB functions. For all higher levels of acceleration, the function block is compiled to C or C++ code, which does not have any access to the MATLAB Engine (because it is intended for deploying to a real-time system or to external hardware.)

It is possible to plot from MATLAB Function Blocks with no more than one level of acceleration turned on, if you declare

https://www.mathworks.com/help/fixedpoint/ref/coder.extrinsic.html

coder.extrinsic('stem');

[Sarfaraz Ahmed]

Thank you. I declare k in top. let me show you full code. Also I dont want any thing when clock is 0. I want value at output in every iteration when clk1 is 1. let say while loop run 16 time so at out put there must be 16 different values without repetition. I dont want value overwrite ? how can I do this ?

function y  = sample(clk1)

% Sampling input signal

persistent x1; 

if isempty(x1)   % Initialization
  x1=0;
end

persistent k; 

if isempty(k)   % Initialization
  k=1;
end

fs=500e3; %Very high sampling rate 500 kHz
f=10e3; %Frequency of sinusoid
nCyl=5; %generate five cycles of sinusoid
t=0:1/fs:nCyl*1/f; %time index
x=sin(2*pi*f*t);

plot(t,x)
title('Continuous sinusoidal signal');
xlabel('Time(s)');
ylabel('Amplitude');

subplot(2,1,1);
plot(t,x);
hold on;

fs1=50e3; %50kHz sampling rate
t1=0:1/fs1:nCyl*1/f; %time index
size= length(t1);

if clk1==1 
    while k<=size
          x1=sin(2*pi*f*t1(1));
         k=k+1;
         break;
  %  stem(t1,x1);
    end
end

y=x1;

also, in code where I should write "coder.extrinsic('stem');" so that all samples can be plotted ? Thanks

[Walter Roberson]

Also I dont want any thing when clock is 0.

Then you are using the wrong configuration. You should be using if/else to determine whether the block should be run, or you could use a switch block, or a triggered subsystem, and there are probably other possibilities at all.

A block like you are using must produce the same size of output every time it is called with the same size of input. It can emit "dummy" values, or values that signal to something downstream that the downstream is to ignore the values, but if it is not to produce an output then it should not be invoked.

You can put the coder.extrinsic() call after the "function" line.

Note that after the first time that the while loop ends, because you never reset k, the only way that you could run more iterations of the while loop would be if somehow the length of t1 increased.

[Sarfaraz Ahmed]

Thank you. Yes, I agree with you I dont want to run at clk1=0. then what should write in else statement so that block will not run at clk1=0 ? Actually, if you see an attached snap only last value in display. it overwrites in every iteration which I dont want. I need all sampled values at output. for this how can I make it possible in the code ?

if clk1==1 
    while k<=size
          x(k)=sin(2*pi*f*t(k));
        %  coder.extrinsic('stem');
         k=k+1;
         break;
  %  stem(t1,x1);
   end
end

Thanks

[Walter Roberson]

I need to head to bed now, sorry.

[Sarfaraz Ahmed]

ok. Thank you so much sir. I will be glade when you again come please get back to this thread.

[Sarfaraz Ahmed]

Hi. I do not want to run the model when clk1=0; how can I modify my code ? what it does basically when clk1==0 it scroll or go through a all blocks in the model, which I do not want. could you please help me on this ? below is a clk1 code and attached snap.

function [Vin]   = sample(clk1)
coder.extrinsic('stem');

% Sampling input signal1

persistent M; 

if isempty(M)   % Initialization
  M=1;
end

persistent x1; 

if isempty(x1)   % Initialization
  x1=0;
end

fs=500e3; %Very high sampling rate 500 kHz
f=10e3; %Frequency of sinusoid
nCyl=5; %generate five cycles of sinusoid
t=0:1/fs:nCyl*1/f; %time index
x=sin(2*pi*f*t);

subplot(2,1,1);
plot(t,x)
title('Sampled Sinusoidal Signal');
xlabel('Time(s)');
ylabel('Amplitude');
hold on;

%(0:2^-6:5^-4)
fs1=50e3; %50kHz sampling rate
t1=0:1/fs1:nCyl*1/f; %time index
size= length(t1);

if clk1==1   
    while M<=size
          x1=sin(2*pi*f*t1(M));
          stem(t1(M),x1);  % plotting discrete samples on the input signal1  
          M=M+1;              
          break;         
    end

end

Vin=x1;

Thanks

[Walter Roberson]

You should be using a triggered subsystem if the code is not to run at all when the control signal is 0.

Note: in such a case you would no longer need clk1 as an input, as the reconfigured block would only get run when clk1 was 1.

[Sarfaraz Ahmed]

Thanks. Let me use triggered system.

Answer 2

[Honglei Chen]

Do you get an error? What is the error message? Looks like you may have some dimension issues? An alternative way is to control the calling of this block, like in a subsystem so it does not get triggered when clock is 0.

HTH

[Sarfaraz Ahmed]

Thank you. I am already using subsystem block as you see in attached file. there was dimension error, however those error resolved by setting variable sizes. Now, what problem I am facing is I have to generate the clock with respect to time so that it sample the input signal at the rising/falling edge of clock and then later I have to add some delay in the clock. Thats why I require time based clock where I can add delay as well. In simulink there is clock but its using simulation time. which I cannot customized in term of time. how can I generate that clock or how can write matlab code to generate time based clock which sample the data at 1khz sampling frequency at the rising edge ?

Thanks is Advance

[Walter Roberson]

The clock is a signal. You can put a delay block on the signal. Or you could use a pulse generator such as https://www.mathworks.com/help/simulink/slref/pulsegenerator.html

[Sarfaraz Ahmed]

Thanks. I am using this with delay but no effect it sample at same time. how can I do this so that it sample according to clock delay. I think the clock is not properly time based . I attached a snap please have a look and my sampler code below:

function Vin = sample(ip) coder.extrinsic('stem');

persistent x1;

if isempty(x1) % Initialization x1=0; end

persistent M;

if isempty(M) % Initialization M=1; end

% Sampling input signal1

f=10e3; %Frequency of sinusoid nCyl=5; %generate five cycles of sinusoid %(0:2^-6:5^-4) fs1=50e3; %50kHz sampling rate t1=0:1/fs1:nCyl*1/f; %time index size= length(t1);

%if clk1==1

    while M<=size
          x1=sin(2*pi*f*t1(M));
          stem(t1(M),x1);  % plotting discrete samples on the input signal1  
          M=M+1;              
          break;         
    end

%end

Vin=x1;

what if I use "pulstran" function and embed in subblock ? but when i use this function it shows an error "Function output 'y' cannot be an mxArray in this context. Consider preinitializing the output variable with a known type." The code for pulse is :

function y = pulse() coder.extrinsic('pulstran');

t=0:0.01:10; %Time vector w = 1; %pulse width d= w/2:w*2:10; %delay vector y2=pulstran(t,d,'rectpuls',w); subplot(2,1,1); plot(t,y2); set(gca,'Ylim',[-0.1 1.1]); xlabel('Time(s)');

y=y2;

I want it sample whenever clock pusle at the rising edge so when it with delays it should sample with delay. Please help me in this regard. Thanks