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waitfor

Pause code execution to achieve desired execution rate

Description

example

waitfor(rate) pauses execution until the code reaches the desired execution rate. The function accounts for the time that is spent executing code between waitfor calls.

numMisses = waitfor(rate) returns the number of iterations missed while executing code between calls.

Examples

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Create a rate object that runs at 1 Hz.

r = rateControl(1);

Start a loop using the rateControl object inside to control the loop execution. Reset the object prior to the loop execution to reset timer. Print the iteration and time elapsed.

reset(r)
for i = 1:10
	time = r.TotalElapsedTime;
	fprintf('Iteration: %d - Time Elapsed: %f\n',i,time)
	waitfor(r);
end
Iteration: 1 - Time Elapsed: 0.002921
Iteration: 2 - Time Elapsed: 1.001767
Iteration: 3 - Time Elapsed: 2.001443
Iteration: 4 - Time Elapsed: 3.001479
Iteration: 5 - Time Elapsed: 4.002085
Iteration: 6 - Time Elapsed: 5.001422
Iteration: 7 - Time Elapsed: 6.001002
Iteration: 8 - Time Elapsed: 7.001471
Iteration: 9 - Time Elapsed: 8.001282
Iteration: 10 - Time Elapsed: 9.001391

Each iteration executes at a 1-second interval.

Input Arguments

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Rate object, specified as a handle. This object contains the information for the desired rate and other information about the execution. See rateControl for more information.

Output Arguments

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Number of missed task executions, returned as a scalar. waitfor (Robotics System Toolbox) returns the number of times the task was missed in the Rate object based on the LastPeriod time. For example, if the desired rate is 1 Hz and the last period was 3.2 seconds, numMisses returns 3.

Version History

Introduced in R2016a