Blink LED at specify time with Matlab - Arduino

Hi, I want to turn on LED for a given time such as 2 minutes and then it will turn off by using Matlab with Arduino hardware. I already search how to code it but I have no idea how to do it. The code below is my trial.

 time = str2num(get(handles.edit3,'String'));
 S = seconds(time);
if S > 0
        writeDigitalPin(a, 'D13',1);
    else
        writeDigitalPin(a, 'D13', 0);
end

[Jan]

@melisa: Please mention, how this question is related to Matlab. How is the LED connected to Matlab? Without knowing this detail, an answer would required to guess.

[melisa samad]

hi, thank you for replying and sorry for my mistake. I already edit my question.

Answer 1

[Jan]

time = str2num(get(handles.edit3,'String'));
% S    = seconds(time);  % [EDITED] Not needed
writeDigitalPin(a, 'D13', 1);
pause(time);             % [EDITED] assumed, that edit3 contains the seconds
writeDigitalPin(a, 'D13', 0);

Or with a timer, which does not block Matlab:

TimerH = timer('TimerFcn', {TimerCB, 'off', a}, ...
               'StartDelay', time, ...   % [EDITED] S -> time
               'ExecutionMode', 'SingleShot', ...
               'StartFcn', {TimerCB, 'on', a});
start(TimerH);

which calls the Timer callback function at starting and stopping:

function TimerCB(TimerH, EventData, Cmd, a)
switch Cmd
  case 'on'
    writeDigitalPin(a, 'D13', 1);
  case 'off'
    writeDigitalPin(a, 'D13', 0);
end
end

[Walter Roberson]

Note: on MS Windows, pause() has a resolution of 0.01 seconds. On OS-X and Linux the resolution is finer grained (but a bit complicated on OS-X.)

[melisa samad]

I got an error for pause(S). Why is it?

[Walter Roberson]

Jan probably overlooked (as did I) that seconds() returns a duration object, and that you cannot pass a duration object to pause(). You would

pause(time)

instead -- presuming that time is a variable holding the length of time to keep the LED lit.

[melisa samad]

oo..okay, now I learn something from you guys. Thank you so much for helping me.

[Jan]

@melissa: Whenever you mention in the forum, that you get an error, post a copy of the complete error message. This helps to understand what's going on.

[melisa samad]

okay, I will take note. Thank you

[ishani uthpala]

thank you very much it's work

Answer 2

[Madhu Govindarajan]

You can use tic and toc for this. When you run tic it starts a stopwatch style timer, you can then use toc to know the elapsed time and use a while loop to check if it is still less than your desired elapsed time.

[melisa samad]

how to done it?

[Walter Roberson]

timelimit = 2*60;
writeDigitalPin(a, 'D13',1);
start = tic;
while toc(start) < timelimit
  pause(0.01);    %do _something_, even if just a useless computation
end
writeDigitalPin(a, 'D13', 0);