Configure a callback in App Designer to be non-interruptable

I'm using USB connected Arduino device and have the following line:

configureCallback(app.PicoCom,"terminator",@app.PicoInput);

The function app.PicoInput does it's job, but I would like it to complete before going back to the main program. If a function has a component that calls it then the function will be the "callback area" of the app and the component has callback execution control. Since this function is called by an interrupt and is set up by startupFcn(app) it doesn't have a component. How can I make it non-interruptable without messing with flags and mutex?

Answer 1

[Walter Roberson]

The secrets to making a function uninterruptible is:

• write the code all on one line. MATLAB checks for interrupts at the beginning of each line of code, so if you write it all on one line then there will be no opportunity to interrupt
• write the code entirely in terms of built-in functions. You might have prevented interrupts by writing all on one line, but if what you are calling is MATLAB code that was written on multiple lines then MATLAB will be checking for interrupts at the beginning of those lines.
• do not call pause() or uifigure() or figure() or uiwait() or waitfor() or drawnow()

[Gavin]

It's a bit long to put all on one line (even if I delete comments. But it turns out it doesn't take long so I guess that's not the problem.

...04>@(varargin)app.PicoInput(varargin{:}) 92 0.109 s 0.002 s

(Go back to lag question 2178493-random-lags-while-running-app )

function PicoInput(app,src,~) 
% check if there is more than 1 line. For some reason I don't get another callback!!!
  while (app.PicoCom.NumBytesAvailable>0)
    raw = readline(src); 
    if size(char(raw),2) == 0 
        return;         % This should never happen, but it does!
    end
    ch = char(raw);  % apparently a read line is a string, make it chars
    if (ch(1:1)=='#')    % A debug line from Pico,
        AddDebugText(app,raw); % if DEBUG is on the text will display
% V85 special cases, H ws there, adding V for Odor Test light off
        if ch(2:2)=='V' % Valve test finished
            if app.OdorTestButton.Value
                app.OdorTestButton.Value = 0; % Turn off
                OdorTestButtonValueChanged(app);
            end
        end
        if ch(2:2)=='H'  % #Help! ..Pico not connected correctly
            AddDebugText(app,"Restarting Pico");
            try
                write(app.PicoCom,"x2",'char');   % try rebooting too
            catch
                InitPicoPort(app);
            end
        end
        return;
    else % Important data to be saved?
    % char2num is easy just num = char('x'); but other direction....
        app.PicoType = double(ch(1:1));  % first char always "type" an ascii char
        app.PicoType = uint8(app.PicoType);   % Convert to uint8
        app.PicoData = str2double(ch(2:end)); % numeric data starts at second char
        app.PicoData = uint32(app.PicoData); % save as integer
    end  
    if app.PicoData == 0  % Should never happen but if it does, discard
        return;
    end    
    % Deal with the returned results:
    if (app.status == 2) || (app.status == 3)  % Running (finishing) a trial?
%  V27 SAVE THIS IN THE IN BUFFER during trial and  V28 for "stopping too
% zzz ToDo probably don't need my own input buffer, let USB driver handle it???
% V2.9 add buffer overrun check (Might only be during debug??)
        if (app.InPtr == app.OutPtr) && ~app.BFEmpty
            Message = sprintf("Buffer overrun %c", app.PicoType);
            wt = uiconfirm(app.MouseOdor,Message,"Pico Buffer", ...
               Options="Uh-Oh",Icon = "error"); %#ok
% V84 clear it out            
            app.InitInBuffer;   % Clear/init input buffer
% previously   app.BFEmpty = true;  % Call it empty but leave data for debug
        else
            app.InBuffer(app.InPtr,1) = app.PicoType;
            app.InBuffer(app.InPtr,2) = app.PicoData;
            if app.InPtr<size(app.InBuffer,1)
                app.InPtr =  app.InPtr + 1;
            else
                app.InPtr = 1;
            end
            app.BFEmpty = false;  % Data just added
        end
    else
% Not in a trial but save licks (training), and m'scope sync (always)
        DoLicksNoTrial(app,app.PicoType,app.PicoData)
    end
  end  % end-while
end % PicoInput[]; 

[Walter Roberson]

    if (app.status == 2) || (app.status == 3)  % Running (finishing) a trial?

It is not obvious that app.status is defined at that point.

            app.InBuffer(app.InPtr,1) = app.PicoType;
            app.InBuffer(app.InPtr,2) = app.PicoData;

It is not obvious that app.InBuffer has been defined at that point.

Those are two different data types. If app.InBuffer has not been defined before this, then app.InBuffer will be initialized to the first type assigned to it, which would be uint8. You would need to initialize to uint32 to fit app.PicoData

[Walter Roberson]

        if ch(2:2)=='H'  % #Help! ..Pico not connected correctly

It bugs me that that is not an "elseif" ;-)

[Gavin]

app.status is initialized during startup and well managed.

Data typing is handled in the code, structures are initialized as needed.

e.g.

function InitInBuffer(app)
% Clean out InBuffer reset pointers
app.InBuffer = zeros(40, 2);      % Circular Array init
app.InPtr = 1;      % Where to read
app.OutPtr = 1;     % Where Pico Data goes
app.BFEmpty = true; % No data yet
end

The circular buffer is handled correctly.I use it to get data out of the Windows USB buffer where I can deal with in in my own time. Type isn't changed to a char until it's read from the buffer.

Typ = char(app.InBuffer(app.OutPtr,1));

if ~isletter(Typ) % manage possible error (it never happens)

And BTW the PicoInput code is about 80 lines so not going to fit on one line.

Hasn't been a problem any more with ML2025

[Walter Roberson]

function InitInBuffer(app)
% Clean out InBuffer reset pointers
app.InBuffer = zeros(40, 2);      % Circular Array init

You are not returning app from the function, and app is not a global variable or a shared variable. All changes to app will be lost when the funtion returns.