How to write code for flowchart

I am unable to write the code for the following flowchart. The voltage need to me sampled for 40 micro second

[Walter Roberson]

What ADC hardware are you planning to use for this, and how do you plan to interface to it?

[Mahesh Abdare]

I just want to simulate without hardware

[Mohamad Nazir]

A timer object can be used in this case to schedule the sampling with the desired frequency.

You can check out the documentation about timer object in the following link: https://www.mathworks.com/help/matlab//ref/timer.html

[Walter Roberson]

You cannot use a timer for this purpose. The minimum period for a timer() object is 0.001 which is 25 times too slow for an event that occurs every 40 microseconds.

You could investigate using Stateflow; I do not know how quickly Stateflow can run.

Answer 1

[Walter Roberson]

period = 40e-6;

for REPEATS = 1  : 500
    %box 1, 40 microsecond interrupt
    last_event_time = tic;
    while toc(last_event_time) < period; end  %busy loop

    %box 2, read input voltage
    Input_Voltage = randn() * 20;

    %box 3, assignments
    Array_vin(sample_count) = Input_Voltage;
    Alpha = Input_Voltage;
    
    %box 4, increment
    sample_count = sample_count + 1;
    
    %box 5, test
    if input_voltage >= 0 && input_voltage_previous <= 0 && sample_count > 300
        %box 6, "Yes" block
        Period = sample_count;
        sample_count = 0;
    end
    
    %box 7, "no" box, is executed for "Yes" as well.
    
    input_voltage_previous = input_voltage;
    
    %and so on
end

You will find that in practice the timer could be more than 50 times too slow, but with this tic/toc approach the interval can be fast enough. You cannot use pause() for this purpose, as pause() does not accurately simulate event timing, and in practice the minimum pause is about 3 times too slow for your purposes.

You will find that in practice the array indexing is wrong. MATLAB array indices start from 1.

You will find that in practice you need to have initialized some variables that are not initialized in the flow chart.

But you did not ask for repaired logic, you asked for this flow chart to be implemented.

[Mahesh Abdare]

@Walter Roberson

Showing This error

[Walter Roberson]

Yes, that is a correct implementation of that aspect of the flow chart. The flowchart does not initialize sample_count, so it would have been incorrect for me to have initialized it. The flowchart has bugs, so any accurate implementation must replicate the bugs.

Answer 2

[shivakumar pambala]

Are u writing it for any specific embedded board?

[Walter Roberson]

They said that they want to simulate without hardware.

[shivakumar pambala]

Ok