How to create variable size buffers in Simulimk?

I want to create a vector of data that is output by the RTL-SDR Simulink block. This vector has variable length depending on certain other parameters. I was using a Simulink buffer block to create a vector, however, I am unable to design a variable size buffer in Simulink.

Thank you in advance.

Answer 1

[Anurag Ojha]

Hey Vaibhavee

In order to create a variable size buffers in simulink. You can use MATLAB Function block. MATLAB Function blocks enable you to define custom functions in Simulink models.

Here is a sample code of how you can write function that create a buffer of variable size.

function y = variable_size_buffer(u, len)
    % Declare y as a variable-size signal
    coder.varsize('y', [1, Inf]);
    
    % Initialize the buffer as persistent
    persistent buffer;
    if isempty(buffer)
        buffer = [];
    end
    
    % Append the new data to the buffer
    buffer = [buffer, u];
    
    % Check if the buffer length exceeds the desired length
    if length(buffer) > len
        % Trim the buffer to the desired length
        buffer = buffer(end-len+1:end);
    end
    
    % Output the buffer
    y = buffer;
end

Refer to this MATLAB documentation to get better understanding:

• https://www.mathworks.com/help/simulink/ug/what-is-a-matlab-function-block.html