waitfor

Pause code execution to achieve desired execution rate

Syntax

waitfor(rate)

numMisses = waitfor(rate)

Description

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

Run Loop at Fixed Rate

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: 0.002791
Iteration: 2 - Time Elapsed: 1.001815
Iteration: 3 - Time Elapsed: 2.001612
Iteration: 4 - Time Elapsed: 3.003016
Iteration: 5 - Time Elapsed: 4.003500
Iteration: 6 - Time Elapsed: 5.001666
Iteration: 7 - Time Elapsed: 6.000518
Iteration: 8 - Time Elapsed: 7.000334
Iteration: 9 - Time Elapsed: 8.000999
Iteration: 10 - Time Elapsed: 9.001000

Each iteration executes at a 1-second interval.

Input Arguments

rate — Rate object

handle

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

Output Arguments

numMisses — Number of missed task executions

scalar

Number of missed task executions, returned as a scalar. waitfor 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