Matlab App Designer Update GUI on Object PostSet Event

I am creating a simple GUI to interact with an arduino board over serial. The user will be able to enter desired parameters from the UI, which are stored in a "command state" object, then transmit those parameters on a button push. On the flip-side, health & status updates will come from the arduino periodically and update another "reported state" object, which in turn will update various gauges in the GUI. This latter step is what I'm having trouble with.

In short:

How can GUI elements listen for a change to an object property and update accordingly?

What I have so far:

The object in question is declared as a handle, with "SetObservable" enabled on its properties so the "PostSet" event should be active. For this example, I'll add a single property, the vector P and initialize it as all zeros. For class methods we have a simple constructor and a setter for P.

classdef DroneState < handle

properties (AbortSet, SetObservable)

P = [0, 0, 0, 0]

end

methods

function obj = DroneState(P_in)

% Constructor

if nargin ~= 0

obj.P = P_in;

end

end

function set.P(obj, P_in)

%Set P Values. Accepts a 1x4 array of new values. To leave a

% value unchanged, submit NaN in it's index. Valid Range 0:100.

% Catch bad input array

if length(P_in) ~= 4

disp(P_in);

error("Invalid P Array.\nValid format: [ P1 P2 P3 P4 ]");

end

% Iterate P values, set valid inputs, leave NaN indices.

nan_bool = isnan(P_in);

for i = 1:4

if (P_in(i) >= 0) && (P_in(i) <= 100)

obj.P(i) = P_in(i);

elseif nan_bool(i)

continue

else

error("Invalid P Value: %d\nAcceptable range: 0:100 (%%)",P_in(i));

end

end

end

end

end

On the GUI end, I define the two state objects as public properties of the app, and declare them in the startupFcn. I also have a testing button that sets the values of deployed.P

classdef test_stand_control < matlab.apps.AppBase

...

properties (Access = public)

deployed DroneState % Describes the current state of the drone, as recieved from teensy serial

commands DroneState % Describes the command state of the drone, to be deployed to teensy serial

end

% Callbacks that handle component events

methods (Access = private)

% Code that executes after component creation

function startupFcn(app, port, baud)

% Instatiate DroneState objects (empty)

app.deployed = DroneState;

app.commands = DroneState;

end

% Button pushed function: TestButton

function TestButtonPushed(app, event)

app.deployed.P = [10 20 30 40];

end

end

end

Finally, I have another private function within the app that (should) update the values of four gauges when the P PostSet event is caught:

methods (Access = private)

function deployedP(app,src,event)

% Update P Gauges on display in the event that updates are made

% to the deployed DroneState values.

disp("deployedPSetCallback Triggered.")

app.P1Gauge.Value = app.deployed.P(1);

app.P2Gauge.Value = app.deployed.P(2);

app.P3Gauge.Value = app.deployed.P(3);

app.P4Gauge.Value = app.deployed.P(4);

end

end

I understand logically that the missing component is a listener waiting for the P PostSet event, but I cannot figure out how to deploy this despite many attempts. Including:

P_listener = addListener(app.deployed,'P','PostSet',...

@(src, event) deployedP(app,src,event));

in the startupFcn throws the error:

I know I can't be the only one trying to solve this problem, please help!

Answer 1

[Ian Andrzejczak]

The only error was that addlistener should be all lowercase. Going to leave this up for whoever might need it in the future though.