In this section, execution period of a real time task is actually measured.
A little fluctuation of the period might be measured when the sampling period in the real time task is short enough.
- Program source
- loadable module: period_module.c
- user space program which starts and stop the module: period_app.c
- header file: period.h
- Program source of device driver for D/A converter (A/D converter is also included)
- header file: adc.h (the same as the previous page)
- driver body: adc.c (the same as the previous page)
- Makefile (the same as the previous page)
Install the module `period_module.o' by the same procedure explained in the previous page.
This program does not output the square wave until the start command is issued by the user space program.
% ./period_app > foo.dat Starting real time task ... done. Waiting for record ... done.When `period_app' starts, start command is issued to the module.
Then the real time task is started, and is automatically stopped after for a while.
The measurement result is stored in the file `foo.dat'.
% matlab -nojvm
< M A T L A B >
Copyright 1984-2001 The MathWorks, Inc.
Version 6.1.0.450 Release 12.1
May 18 2001
To get started, type one of these: helpwin, helpdesk, or demo.
For product information, visit www.mathworks.com.
>> load foo.dat;
>> plot(foo(:,1), foo(:,2))
Here, a graph is appeared.
>> quit
Example:
The above example shows that the execution period is about 200 [micro sec] which is defined as SAMPLING_PERIOD in `period.h' with small fluctuation.