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App Designer not identifying 'readVoltage'

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Michael Pineda
Michael Pineda on 21 Sep 2020
Answered: Fazli Wadood on 22 Mar 2023
I had made a callback for a button in App Designer that when pushed would read voltages from an arduino 'A0' pin and it was wokring. Suddenly when I tried to run the app again I was getting an error of "Undefined function 'readVoltage' for input arguments of type 'double'". I had not changed the code in between this happening but now I cannot fix it.
function ButtonPushed(app, event)
clc
global b
x1=0;
global go
go=true;
while go
tempA1 = readVoltage(b, 'A0');
tempA2 = 32+(9/5)*(tempA1*100);
x1=[x1 tempA2];
plot(app.UIAxes,x1);
drawnow
pause(1);
end
end

Answers (2)

Ameer Hamza
Ameer Hamza on 21 Sep 2020
You have used 'b' as a global variable. In the base workspace, you need to define it as an Arduino object
b = arduino;
If it has some other type, you will get this error
  4 Comments
Ameer Hamza
Ameer Hamza on 21 Sep 2020
Have you typed global b in command window?
Michael Pineda
Michael Pineda on 21 Sep 2020
Yes I did and the error continues to be displayed

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Fazli Wadood
Fazli Wadood on 22 Mar 2023
I have use this its working.
clc
global b
b = arduino;
x1=0;
global go
go=true;
while go
tempA1 = readVoltage(b, 'A0');
tempA2 = 32+(9/5)*(tempA1*100);
x1=[x1 tempA2];
plot(app.UIAxes,x1);
drawnow
pause(1);
end

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