Pause function in matlab for 1 millisecond
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Hi,
I need to pause my matlab program at GUI, because I'm using serial communication, but when I use pause command it only allows me to pause it for 0.01 seconds.
pause(0.01) %in seconds
The thing I need, for example:
pause(0.001) %in seconds, but actually doesn't works
Anyone knows how to pause matlab for 1 millisecond? Thanks for read and answer.
Greetings.
2 Commenti
chandan kumar
il 17 Gen 2017
Modificato: Walter Roberson
il 24 Apr 2023
Hello there,
First use:
pause on % to enable pause function
Now you can use pause function:
pause(x); // delay in seconds (x is non-negative real number)
Walter Roberson
il 17 Gen 2017
Pause is on by default.
On MS Windows, the resolution is only 0.01 seconds and using "pause on" does not change that.
Risposte (9)
AndreasDerFuchs
il 4 Mar 2016
The attached pauses() matlab function combines the above ideas.
It can pause with an accuracy of 0.03 ms on my PC, without using too much CPU-bandwidth, as opposed to an accuracy of 0.8 ms with java.lang.Thread.sleep(ms), or the even worse accuracy of 15 ms with pause().
I've tested the accuracy with:
pauses(0); ii=1:300; d=ii/12345;
for i=ii;
t0=tic; pauses(d(i),t0); t(i)=toc(t0);
end;
fprintf('3 sigma accuracy = %.6f ms\n', std(t-d)*3000);
2 Commenti
akin hunerli
il 14 Mag 2016
hi Hamid Reza saadati, i have the problem with the pause command working on a guide interface then i realised that we have to add a pause command end of the code.
Daniel Shub
il 8 Mag 2012
Getting millisecond timing accuracy is extremely difficult in most programming languages since the underlying clocks are just not that accurate. It really is a question of how much jitter you can tolerate.
That said, the "serial port" tag makes me think you should look at callback functions.
0 Commenti
Andreas Goser
il 8 Mag 2012
Modificato: John Kelly
il 27 Mag 2014
While Jakob's answer is a correct answer to your specific question, you might want to do something different, as the PAUSE command really stops MATLAB from doing stuff.
0 Commenti
Malcolm Lidierth
il 19 Mag 2016
Modificato: Malcolm Lidierth
il 19 Mag 2016
Pause does more than cause a sleep (see the docs) e.g. it flushes the AWT/Swing EDT. The minimum delay will therefore reflect what needs to be done in the background. undocumentedmatlab.com has several relevant posts (see drawnow/pause)
0 Commenti
Jakob Sørensen
il 8 Mag 2012
Doesn't work how? And what Matlab version are you using? In R2011b, running Windows 7, I get the following results
>> tic;pause(0.001);toc;
Elapsed time is 0.009849 seconds.
Which is reasonably close to 1 ms.
7 Commenti
Walter Roberson
il 2 Nov 2015
R2015a on OS-X:
g = @() pause(0.001);
timeit(g, 0)
shows outputs between 0.001255 and 0.001404. (Be sure to use 0 as the second argument or else you end up measuring the time to return the "state" of the timer.)
The result is consistently higher than 1 1/4 millisecond and less than 1 1/2 millisecond in the tests I have done this way. Note that
tic(); pause(0.001); toc()
at the command line is not completely representative due to differences in what is JIT (Just In Time compiled)
Marcel Kraemer
il 5 Feb 2013
Modificato: Marcel Kraemer
il 5 Feb 2013
Hi Guys,
I had the same problem as you and I couldn't find an answer on the internet. So I tried following solution which works percetly well for me.
function delay(seconds)
% function pause the program
% seconds = delay time in seconds
tic;
while toc < seconds
end
end
Cheers, Marcel
1 Commento
Andreas Sprenger
il 27 Set 2013
Hi,
on a 32bit Windows System you may use a kernel function. It works quite accurate, I've tested it against hardware timer. Unfortunately I haven't found a solution on 64bit Win7. Any hints are welcome.
Cheers
Andreas
Here an example for 32bit Windows:
if ~libisloaded('QPerf')
% loads kernel functions for time measurement
loadlibrary ('kernel32.dll', @QueryPerformance, 'alias', 'QPerf')
end
% data structure for QueryPerformance...
Value.LowPart = uint32(0);
Value.HighPart = uint32(0);
QStruct = libstruct('s_ULARGE_INTEGER', Value);
% Get performance of the computer
[xval, QFreq] = calllib('QPerf', 'QueryPerformanceFrequency', QStruct);
Frequency = QFreq.HighPart*2^32 + QFreq.LowPart;
% Get t0
[~, QCounter] = calllib('QPerf', 'QueryPerformanceCounter', QStruct);
t0 = (QCounter.HighPart*2^32 + QCounter.LowPart) / Frequency * 1000;
t1 = t0;
% example: wait a second
while t1 - t0 < 1000
[~, QCounter] = calllib('QPerf', 'QueryPerformanceCounter', QStruct);
t1 = (QCounter.HighPart*2^32 + QCounter.LowPart) / Frequency * 1000;
end
% -----
function [methodinfo,structs,enuminfo] = QueryPerformance
%This function was generated by the perl file prototypes.pl called from loadlibary.m on Wed Apr 5 19:40:14 2006
%perl options:'win.i -outfile=QueryPerformance
ival={cell(1,0)}; % change 0 to the actual number of functions to preallocate the data.
fcns=struct('name',ival,'calltype',ival,'LHS',ival,'RHS',ival,'alias',ival);
structs=[];enuminfo=[];fcnNum=1;
% BOOL _stdcall QueryPerformanceCounter(LARGE_INTEGER *);
fcns.name{fcnNum}='QueryPerformanceCounter';
fcns.calltype{fcnNum}='stdcall';
fcns.LHS{fcnNum}='int32';
fcns.RHS{fcnNum}={'s_ULARGE_INTEGERPtr'};
fcnNum = fcnNum+1;
% BOOL _stdcall QueryPerformanceFrequency(LARGE_INTEGER *);
fcns.name{fcnNum}='QueryPerformanceFrequency';
fcns.calltype{fcnNum}='stdcall';
fcns.LHS{fcnNum}='int32';
fcns.RHS{fcnNum}={'s_ULARGE_INTEGERPtr'};
fcnNum = fcnNum+1;
structs.s_ULARGE_INTEGER.packing=8;
structs.s_ULARGE_INTEGER.members=struct('LowPart', 'uint32', 'HighPart', 'uint32');
methodinfo = fcns;
2 Commenti
Andreas Sprenger
il 27 Set 2013
Spostato: DGM
il 24 Apr 2023
Hi,
searching for a solution on 64bit Matlab I came across a workaround. Edit the prototype and change fcns.calltype from 'stdcall' (most common on 32bit Windows systems) to 'cdecl' (C type declaration). It works both on 32bit and 64bit Matlab systems. On 2013a there is a warning that the loader file will not be supported in future.
Andreas
Walter Roberson
il 24 Apr 2023
The Windows task scheduler runs every 15 ms, so you cannot get 0.001 resolution without resorting to something like busy-wait.
See the extended discussion, with specific tests, at
0 Commenti
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