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-@page WordSection1
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- {size:8.5in 11.0in;
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- margin:56.7pt 56.7pt 56.7pt 56.7pt;}
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- /* List Definitions */
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- ol
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-ul
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--->
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-</style>
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-
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-</head>
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-
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-<body bgcolor=white lang=EN-US style='line-break:strict'>
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-
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-<div class=WordSection1>
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-
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-<p class=MsoNormal><b>Task Scheduler – cooperative multitasking for Arduino microcontrollers</b></p>
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-
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-<p class=MsoNormal><b>Version 1.51: 2015-09-20</b></p>
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-
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-<p class=MsoNormal> </p>
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-
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-<p class=MsoNormal> </p>
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-
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-<p class=MsoNormal><b>REQUIREMENT</b>:</p>
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-
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-<p class=MsoNormal>A lightweight implementation of the task scheduling
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-supporting:</p>
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-
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-<ol style='margin-top:0in' start=1 type=1>
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- <li class=MsoNormal>execution period (n times per second)</li>
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- <li class=MsoNormal>number of iterations (n times)</li>
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- <li class=MsoNormal>execution of tasks in predefined sequence</li>
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- <li class=MsoNormal>dynamic change of the execution parameters for both tasks
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- and execution schedule</li>
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- <li class=MsoNormal>power saving via entering IDLE sleep mode if no tasks are
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- scheduled to run</li>
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-</ol>
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-
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-<p class=MsoNormal> </p>
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-
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-<p class=MsoNormal> </p>
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-
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-<p class=MsoNormal><b>IDEA</b>:</p>
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-
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-<p class=MsoNormal>“Task” is a container concept that links together:</p>
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-
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-<ol style='margin-top:0in' start=1 type=1>
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- <li class=MsoNormal>Execution interval</li>
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- <li class=MsoNormal>Number of execution iterations</li>
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- <li class=MsoNormal>A piece of code performing the task activities (callback
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- function)</li>
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-</ol>
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-
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-<p class=MsoNormal> </p>
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-
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-<p class=MsoNormal>Tasks are linked into execution chains, which are processed
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-by the “Scheduler” in the order they are linked.</p>
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-
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-<p class=MsoNormal> </p>
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-
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-<p class=MsoNormal>Tasks are responsible for supporting cooperative
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-multitasking by being “good neighbors”, i.e., running their callback functions
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-in a non-blocking way and releasing control as soon as possible. </p>
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-
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-<p class=MsoNormal> </p>
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-
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-<p class=MsoNormal>“Scheduler” is executing Tasks' callback functions in the
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-order the tasks were added to the chain, from first to last. Scheduler stops
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-and exists after processing the chain once in order to allow other statements
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-in the main code of <b>loop()</b> function to run. This a “scheduling
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-pass”.</p>
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-
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-<p class=MsoNormal> </p>
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-
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-<p class=MsoNormal>If compiled with <span style='font-family:"Courier New"'>_TASK_SLEEP_ON_IDLE_RUN</span>
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-enabled, the scheduler will place processor into IDLE sleep mode (for
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-approximately 1 ms, as the timer interrupt will wake it up), after what is
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-determined to be an “idle” pass. An Idle Pass is a pass through the chain when
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-no Tasks were scheduled to run their callback functions. This is done to avoid
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-repetitive empty passes through the chain when no tasks need to be executed. If
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-any of the tasks in the chain always requires immediate execution (aInterval =
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-0), then there will be no end-of-pass delay.</p>
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-
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-<p class=MsoNormal> </p>
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-
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-<p class=MsoNormal><b>Note: </b>Task Scheduler uses <b>millis()</b> to
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-determine if tasks are ready to be invoked. Therefore, if you put your device
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-to any “deep” sleep mode disabling timer interrupts, the <b>millis()</b> count
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-will be suspended, leading to effective suspension of scheduling. Upon wake up,
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-active tasks need to be re-enabled, which will effectively reset their internal
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-time scheduling variables to the new value of <b>millis(). </b>Time spent in
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-deep sleep mode should be considered “frozen”, i.e., if a task was scheduled to
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-run in 1 second from now, and device was put to sleep for 5 minutes, upon wake
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-up, the task will still be scheduled 1 second from the time of wake up.
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-Executing <b>enable() </b>function on this tasks will make it run as soon as
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-possible. This is a concern only for tasks which are required to run in a truly
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-periodical manner (in absolute time terms). </p>
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-
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-<p class=MsoNormal> </p>
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-
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-<p class=MsoNormal> </p>
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-
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-<p class=MsoNormal> </p>
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-
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-<p class=MsoNormal><b>COMPILE PARAMETERS:</b></p>
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-
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-<p class=MsoNormal>This library could be compiled with several options. </p>
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-
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-<p class=MsoNormal>These parameters must be defined before inclusion of the
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-library header file into the sketch.</p>
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-
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-<p class=MsoNormal> </p>
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-
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-<p class=MsoNormal>#define <b>_TASK_TIMECRITICAL</b></p>
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-
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-<p class=MsoNormal>...will compile the library with time critical tracking
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-option enabled.</p>
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-
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-<p class=MsoNormal>Time critical option keeps track where next execution time
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-of the task falls, and makes it available via API through Task::<b> getOverrun()
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-</b>function. If <b>getOverrun </b>returns a negative value, this Task’s next
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-execution time is in the past, and task is behind schedule. This most probably
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-means that either task’s callback function runtime is too long, or the
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-execution interval is too short (then schedule is too aggressive).</p>
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-
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-<p class=MsoNormal>A positive value indicates that task is on schedule, and
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-callback functions have enough time to finish before the next scheduled pass. </p>
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-
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-<p class=MsoNormal> </p>
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-
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-<p class=MsoNormal>#define <b>_TASK_SLEEP_ON_IDLE_RUN</b></p>
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-
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-<p class=MsoNormal>...will compile the library with the <b>sleep</b> option
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-enabled (AVR boards only).</p>
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-
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-<p class=MsoNormal>When enabled, scheduler will put the microcontroller into <b>SLEEP_MODE_IDLE</b>
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-state if none of the tasks’ callback functions were activated during pass. <b>IDLE</b>
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-state is interrupted by timers once every 1 ms. Helps conserve power. Device
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-in SLEEP_MODE_IDLE wakes up to all hardware and timer interrupts, so scheduling
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-is kept current.</p>
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-
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-<p class=MsoNormal> </p>
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-
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-<p class=MsoNormal><b>NOTE: above parameters are DISABLED by default, and need
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-to be explicitly enabled.</b></p>
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-
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-<p class=MsoNormal> </p>
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-<p class=MsoNormal> </p>
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-
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-<p class=MsoNormal> </p>
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-
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-<p class=MsoNormal><b>API DOCUMENTATION:</b></p>
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-
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-<p class=MsoNormal> </p>
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-
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-<p class=MsoNormal><b>TASKS:</b></p>
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-
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|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal>CREATION:</p>
|
|
|
-
|
|
|
-<p class=MsoNormal><b>Task();</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>Default constructor. </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>Takes no parameters and creates
|
|
|
-a task that could be scheduled to run at every scheduling pass indefinitely,
|
|
|
-but does not have a callback function defined, so no execution will actually
|
|
|
-take place. </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>All tasks are created <b>disabled</b>
|
|
|
-by default.</p>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='page-break-after:avoid'><b>Task(unsigned long aInterval,
|
|
|
-long aIterations, void (*aCallback)(), Scheduler* aScheduler, bool aEnable);</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>Constructor with parameters. </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>Creates a task that is scheduled
|
|
|
-to run every <aInterval> milliseconds, <aIterations> times,
|
|
|
-executing <aCallback> function on every pass. </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:71.45pt;text-indent:-.25in'>1.<span
|
|
|
-style='font-size:7.0pt;font-family:"Times New Roman","serif"'>
|
|
|
-</span>aInterval is in milliseconds</p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:71.45pt;text-indent:-.25in'>2.<span
|
|
|
-style='font-size:7.0pt;font-family:"Times New Roman","serif"'>
|
|
|
-</span>aIteration in number of times, -1 for indefinite execution<br>
|
|
|
-<b>Note: </b>Tasks do not remember the number of iteration set initially. After
|
|
|
-the iterations are done, internal iteration counter is 0. If you need to
|
|
|
-perform another set of iterations, you need to set the number of iterations
|
|
|
-again. <br>
|
|
|
-<b>Note: </b>Tasks which performed all their iterations remain active. </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:71.45pt;text-indent:-.25in'>3.<span
|
|
|
-style='font-size:7.0pt;font-family:"Times New Roman","serif"'>
|
|
|
-</span>aCallback is a pointer to a void function without parameters</p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:71.45pt;text-indent:-.25in'>4.<span
|
|
|
-style='font-size:7.0pt;font-family:"Times New Roman","serif"'>
|
|
|
-</span>aScheduler – <b>optional</b> reference to existing scheduler. If
|
|
|
-supplied (not NULL) this task will be appended to the task chain of the current
|
|
|
-scheduler). <b>Default=NULL</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:71.45pt;text-indent:-.25in'>5.<span
|
|
|
-style='font-size:7.0pt;font-family:"Times New Roman","serif"'>
|
|
|
-</span>aEnable – <b>optional</b>. Value of <b>true </b>will create task
|
|
|
-enabled. <b>Default = false</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>All tasks are created <b>disabled</b>
|
|
|
-by default (unless aEnable = true). You have to explicitly enable the task for
|
|
|
-execution.</p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>Enabled task is scheduled for execution
|
|
|
-immediately. Enable tasks with delay (standard execution interval or specific
|
|
|
-execution interval) in order to defer first run of the task.</p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal><b>INFORMATION</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>The following 3 “getter”
|
|
|
-functions return task status (enabled/disabled), execution interval in
|
|
|
-milliseconds, number of <b><i>remaining</i></b> iterations. </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><b>bool isEnabled() </b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><b>unsigned long getInterval()</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><b>long getIterations() </b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><b> </b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><b>long getOverrun()</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>If library is compiled with <span
|
|
|
-style='font-family:"Courier New"'>_TASK_TIMECRITICAL</span> enabled, tasks are
|
|
|
-monitored for “long running” scenario. A “long running” task is a task that
|
|
|
-does not finish processing its callback functions quickly, and thus creates a
|
|
|
-situation for itself and other tasks where they don't run on a scheduled
|
|
|
-interval, but rather “catch up” and are behind. When task scheduler sets
|
|
|
-the next execution target time, it adds Task's execution interval to the
|
|
|
-previously scheduled execution time:</p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>
|
|
|
-<b>next execution time = previous execution time + task execution interval</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>If <b>next execution time</b> happens
|
|
|
-to be already in the past (<b>next execution time</b> < <b>millis()</b>), then
|
|
|
-task is considered <b><i>overrun</i></b>. <b>GetOverrun</b> function returns
|
|
|
-number of milliseconds between next execution time and current time. If the <b>value
|
|
|
-is negative</b>, the task is overrun by that many milliseconds. </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>Positive value indicate number
|
|
|
-of milliseconds of slack this task has for execution purposes. </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal><b>bool isFirstIteration()</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><b>bool isLastIteration()</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>For tasks with a defined number
|
|
|
-of iterations, indicates whether current pass is a first or a last iteration of
|
|
|
-the task (respectively). </p>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='page-break-after:avoid'><b>CONTROL:</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal><b>void enable();</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>Enables the task, and schedules
|
|
|
-it for immediate execution (without delay) at this or next scheduling pass
|
|
|
-depending on when the task was enabled. Scheduler will execute the next pass
|
|
|
-without any delay because there is a task which was enabled and requires
|
|
|
-execution. </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal><b>void delay();</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>Schedules the task for execution
|
|
|
-after a delay (aInterval), but does not change the enabled/disabled status of
|
|
|
-the task. </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><b> </b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><b>void enableDelayed();</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>Enables the task, and schedules
|
|
|
-it for execution after a delay (aInterval). </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal><b>void enableDelayed (unsigned long aDelay);</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>Enables the task, and schedules
|
|
|
-it for execution after a specific delay (aDelay, which maybe different from aInterval).
|
|
|
-</p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal><b>void restart();</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>For tasks with limited number of
|
|
|
-iterations only, <b>restart</b> function will re-enable the task, set the
|
|
|
-number of iterations back to when the task was created and and schedule the
|
|
|
-task for execution as soon as possible.</p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal><b>void restartDelayed (unsigned long aDelay);</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>Same as <b>restart() </b>function,
|
|
|
-with the only difference being that Task is scheduled to run first iteration
|
|
|
-after a delay = <b>aDelay</b> milliseconds.</p>
|
|
|
-
|
|
|
-<p class=MsoNormal><b> </b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><b>void disable();</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>Disables the task. Scheduler
|
|
|
-will not execute this task any longer, even if it remains in the chain. Task
|
|
|
-can be later re-enabled for execution. </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal><b>void disableOnLastIteration (bool aBool);</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>Controls iterative task behavior
|
|
|
-on the last iteration. If <b>aBool</b> is <b>true</b> task will be disabled
|
|
|
-after last iteration. If <b>aBool</b> is <b>false</b>, task will remain active
|
|
|
-(but not invoked until new number of iterations is set)</p>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal><b>void set(unsigned long aInterval, long aIterations, void (*aCallback)());</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>Allows dynamic control of all
|
|
|
-task execution parameters in one function call. If task being modified is
|
|
|
-active, it will be scheduled for execution immediately. </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal>Next three “setter” functions allow changes of individual
|
|
|
-task execution control parameters. </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><b>void setInterval (unsigned
|
|
|
-long aInterval) </b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><b>void setIterations (long aIterations)
|
|
|
-</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><b>void setCallback (void
|
|
|
-(*aCallback)()) </b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal><b>Note: </b>Next execution time calculation takes place <b>after</b>
|
|
|
-the callback function is called, so new interval will be used immediately by
|
|
|
-the scheduler. For the situations when one task is changing the interval
|
|
|
-parameter for the other, <b>setInterval</b> function calls <b>delay </b>explicitly
|
|
|
-to guarantee schedule change, however it <b>does not </b>enable the task if
|
|
|
-task is disabled. If task being modified is active, <b>setIterations </b>will
|
|
|
-make the task be scheduled for execution immediately.</p>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal><b> </b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><b>TASK SCHEDULER:</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal><b>CREATION:</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-bottom:12.0pt'><b>Scheduler()</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>Default constructor. </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>Takes no parameters. Creates
|
|
|
-task scheduler with default parameters and an empty task queue. </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal><b>void init()</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>Initializes the task queue and
|
|
|
-scheduler parameters, Executed as part of constructor, so don't need to be
|
|
|
-explicitly called after creation.</p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><b>Note: </b>be default (if
|
|
|
-compiled with <span style='font-family:"Courier New"'>_TASK_TIMECRITICAL</span>
|
|
|
-enabled) scheduler is allowed to put processor to IDLE sleep mode. If this
|
|
|
-behavior was changed via <b>allowSleep() </b>function, <b>inti() </b>will <b>NOT</b>
|
|
|
-reset allow sleep particular parameter. </p>
|
|
|
-
|
|
|
-<p class=MsoNormal><br>
|
|
|
-<b>void addTask(Task& aTask)</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>Adds task aTask to the execution
|
|
|
-queue (or chain) of tasks by appending it to the end of the chain. If two tasks
|
|
|
-are scheduled for execution, the sequence will match the order tasks are
|
|
|
-appended to the chain. However, in reality, due to different timing of task
|
|
|
-execution, the actual order will be different. </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><b>Note: </b>Currently, changing
|
|
|
-the execution dynamically is not supported. </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>If you need to reorder the queue
|
|
|
-– initialize the scheduler and re-add the tasks in a different order. </p>
|
|
|
-
|
|
|
-<p class=MsoNormal><br>
|
|
|
-<b>void deleteTask(Task& aTask)</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>Deletes task aTask from the
|
|
|
-execution chain. The chain of remaining tasks is linked together (i.e</p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>if original task chain is 1 →
|
|
|
-2 → 3 → 4, deleting 3 will result in 1 → 2 → 4).</p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><b>Note: </b>it is not required
|
|
|
-to delete a task from the chain. A disabled task will not be executed anyway,
|
|
|
-but you save a few microseconds per scheduling pass by deleting it, since it is
|
|
|
-not even considered for execution. </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>An example of proper use of this
|
|
|
-function would be running some sort of <b>initialize</b> task in the chain, and
|
|
|
-then deleting it from the chain since it only needs to run once. </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal><b>void allowSleep(bool aState) </b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>Available in API only if compiled
|
|
|
-with <span style='font-family:"Courier New"'>_TASK_TIMECRITICAL</span> enabled.
|
|
|
-Controls whether scheduler is allowed (<b>aState =true</b>), or not (<b>aState =false</b>)
|
|
|
-to put processor into IDLE sleep mode in case not tasks are scheduled to run.</p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>The <b>default</b> behavior of
|
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-scheduler upon creation is to allow sleep mode. </p>
|
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|
-
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-<p class=MsoNormal><br>
|
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-<b>void enableAll()</b></p>
|
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-
|
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-<p class=MsoNormal><b>void disableAll()</b></p>
|
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|
-
|
|
|
-<p class=MsoNormal> </p>
|
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-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>enables and disables
|
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|
-(respectively) all tasks in the chain. Convenient if your need to
|
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|
-enable/disable majority of the tasks (i.e. disable all and then enable one). </p>
|
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|
-
|
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|
-<p class=MsoNormal style='margin-bottom:12.0pt'><br>
|
|
|
-<b>Task& currentTask()</b></p>
|
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-
|
|
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-<p class=MsoNormal style='margin-left:35.45pt'>Returns reference to the task,
|
|
|
-currently executing via <b>execute()</b> loop. Could be used by callback
|
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|
-functions to identify which of the </p>
|
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|
-
|
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|
-<p class=MsoNormal><br>
|
|
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-<b>void execute()</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'>Executes one scheduling pass,
|
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|
-including end-of-pass sleep. This function typically placed inside the <b>loop()</b>
|
|
|
-function of the sketch. Since <b>execute</b> exits after every pass, you can
|
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|
-put additional statements after <b>execute</b> inside the <b>loop()</b> </p>
|
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|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
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-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
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-
|
|
|
-<p class=MsoNormal style='page-break-after:avoid'><b>IMPLEMENTATION SCENARIOS
|
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|
-AND IDEAS:</b></p>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<ol style='margin-top:0in' start=1 type=1>
|
|
|
- <li class=MsoNormal><b>EVENT DRIVEN PROGRAMMING</b></li>
|
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|
-</ol>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal>Each of the processes of your application becomes a separate
|
|
|
-and distinct programming area, which may or may not interact and control each
|
|
|
-other. </p>
|
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|
-
|
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-<p class=MsoNormal> </p>
|
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|
-
|
|
|
-<p class=MsoNormal>Example: </p>
|
|
|
-
|
|
|
-<p class=MsoNormal>In a plant watering system you need to measure soil
|
|
|
-humidity, control pump and display the results</p>
|
|
|
-
|
|
|
-<p class=MsoNormal>Each of the areas becomes a task:</p>
|
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|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
|
|
|
-margin-left:35.45pt'><span style='font-size:10.0pt;font-family:"Courier New"'>Task
|
|
|
-<b>tMeasure</b> (TMEASURE_INTERVAL*SECOND, -1, &measureCallback);<br>
|
|
|
-Task <b>tWater</b> (TWATER_INTERVAL*SECOND, RETRIES,
|
|
|
-&waterCallback);<br>
|
|
|
-Task <b>tDisplay</b> (TDISPLAY_INTERVAL*SECOND, -1, &displayCallback); </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
|
|
|
-margin-left:35.45pt'><span style='font-size:10.0pt;font-family:"Courier New"'>Scheduler
|
|
|
-<b>taskManager</b>;</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal>Further, once you turn on the pump, you keep it running for
|
|
|
-TWATER_INTERVAL interval and then turn it off. Turning off a pump is also a
|
|
|
-task which only needs to run once for every time the pump is turned on:</p>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
|
|
|
-margin-left:35.45pt'><span style='font-size:10.0pt;font-family:"Courier New"'>Task
|
|
|
-<b>tWaterOff</b> (WATERTIME*SECOND, 1,</span><span style='font-family:"Courier New"'>
|
|
|
-&waterOffCallback);</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal>Example of the callback function:</p>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
-font-family:"Courier New"'>void waterOffCallback() {<br>
|
|
|
- motorOff();<br>
|
|
|
- tWater.enableDelayed();<br>
|
|
|
-}</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
-font-family:"Courier New"'> </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
-font-family:"Courier New"'>or</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
-font-family:"Courier New"'> </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
-font-family:"Courier New"'>void waterCallback() {<br>
|
|
|
- if (tWater.getIterations()) {</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
-font-family:"Courier New"'>// If this is not the last iteration = turn the pump
|
|
|
-on<br>
|
|
|
- motorOn();<br>
|
|
|
- tWaterOff.set(parameters.watertime * SECOND, 1,
|
|
|
-&waterOffCallback);<br>
|
|
|
- tWaterOff.enableDelayed();<br>
|
|
|
- return;<br>
|
|
|
- }</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
-font-family:"Courier New"'>// We could not reach target humidity – something is
|
|
|
-wrong<br>
|
|
|
- motorOff;<br>
|
|
|
- taskManager.disableAll();<br>
|
|
|
- tError.enable();<br>
|
|
|
-}</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Courier New"'> </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>Your
|
|
|
-sample <b>setup</b>() and <b>loop</b>() (partially) are as follows. </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><b><span style='font-family:"Times New Roman","serif"'>Note:
|
|
|
-</span></b><span style='font-family:"Times New Roman","serif"'>please note that
|
|
|
-tWater is <b>not</b> activated during setup(). It is activated by tMeasure
|
|
|
-callback once the watering conditions are met. </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>
|
|
|
-</span><span style='font-family:"Courier New"'>setup()</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Courier New"'>
|
|
|
- ...</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
|
|
|
-margin-left:35.45pt'><span style='font-family:"Courier New"'>
|
|
|
-tWater.setIterations(parameters.retries);<br>
|
|
|
- tWaterOff.setInterval(parameters.watertime * SECOND);<br>
|
|
|
-<br>
|
|
|
-<br>
|
|
|
- taskManager.init();<br>
|
|
|
- taskManager.addTask(tMeasure);<br>
|
|
|
- taskManager.addTask(tDisplay);<br>
|
|
|
- taskManager.addTask(tWater);<br>
|
|
|
- taskManager.addTask(tWaterOff);<br>
|
|
|
- <br>
|
|
|
- tMeasure.enable();<br>
|
|
|
- tDisplay.enable();<br>
|
|
|
-<br>
|
|
|
- currentHumidity = measureHumidity();<br>
|
|
|
-}<br>
|
|
|
-<br>
|
|
|
-<br>
|
|
|
-void loop ()<br>
|
|
|
-{<br>
|
|
|
- taskManager.execute();<br>
|
|
|
-}</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
|
|
|
-margin-left:35.45pt'> </p>
|
|
|
-
|
|
|
-<ol style='margin-top:0in' start=2 type=1>
|
|
|
- <li class=MsoNormal><b><span style='font-family:"Times New Roman","serif"'>“NATIVE”
|
|
|
- SUPPORT FOR FINITE STATE MACHINE</span></b></li>
|
|
|
-</ol>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>Define
|
|
|
-“states” as callback function or functions. Each callback function executes
|
|
|
-activities specific to a “state” and then “transitions” to the next state by
|
|
|
-assigning next callback function to the task. </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>Transition
|
|
|
-from one state to the next is achieved by setting next callback function at the
|
|
|
-end of preceding one. </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><b><span style='font-family:"Times New Roman","serif"'>Note:
|
|
|
-</span></b><span style='font-family:"Times New Roman","serif"'>do not call the
|
|
|
-next callback function. Let the schedule take care of that during the next
|
|
|
-pass. (Thus letting other tasks run). </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>Example:
|
|
|
-Blinking LED 2 times a second could be achieved this way</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>Task
|
|
|
-tLedBlinker (500, -1, &ledOnCallback);</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>Scheduler
|
|
|
-taskManager;</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'> </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>void
|
|
|
-ledOnCallback() {</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>
|
|
|
-turnLedOn();</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>
|
|
|
-tLedBlinker.setCallback(&ledOffCallback);</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>}</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'> </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>void
|
|
|
-ledOffCallback() {</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>
|
|
|
-turnLedOff();</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>
|
|
|
-tLedBlinker.setCallback(&ledOnCallback);</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>}</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'> </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>setup()
|
|
|
-{</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>
|
|
|
-taskManager.init();<br>
|
|
|
- taskManager.addTask(tLedBlinker);</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>
|
|
|
-</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>
|
|
|
-tLedBlinker.enable();</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>}</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'> </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>loop
|
|
|
-() {</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>
|
|
|
-taskManager.execute();</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
|
|
|
-margin-left:35.45pt'><span style='font-family:"Courier New"'>}</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>Obviously
|
|
|
-the example is simple, but gives the idea of how the tasks could be used to go
|
|
|
-through states.</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
-
|
|
|
-<ol style='margin-top:0in' start=3 type=1>
|
|
|
- <li class=MsoNormal><b><span style='font-family:"Times New Roman","serif"'>MULTIPLE
|
|
|
- POSSIBLE CALLBACKS FOR TASK</span></b></li>
|
|
|
-</ol>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>There may
|
|
|
-be a need to select an option for callback function based on certain criteria,
|
|
|
-or randomly. </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>You can
|
|
|
-achieve that by defining an array of callback function pointers and selecting
|
|
|
-one based on the criteria you need. </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>Example:
|
|
|
-when a robot detects an obstacle, it may go left, right backwards, etc. Each of
|
|
|
-the “directions” or “behaviors” are represented by a different callback
|
|
|
-function. </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>Another
|
|
|
-example of using multiple callbacks:</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>You may
|
|
|
-need to “initialize” variables for a particular task.</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>In this
|
|
|
-case, define a tasks with two callbacks:</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
-font-family:"Courier New"'>Task <b>tWork</b> (T_INTERVAL, -1,
|
|
|
-&workCallbackInit);</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
-font-family:"Courier New"'>…</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
-font-family:"Courier New"'>void workCallbackInit() {</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
-font-family:"Courier New"'> // do your
|
|
|
-initializationstuff here</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
-font-family:"Courier New"'> </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
-font-family:"Courier New"'> // finally assigne
|
|
|
-the main callback function </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
-font-family:"Courier New"'>
|
|
|
-tWork.setCallback(&workCallback);</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
-font-family:"Courier New"'>}</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
-font-family:"Courier New"'>void workCallback() {</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
-font-family:"Courier New"'> // main callback
|
|
|
-function</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
-font-family:"Courier New"'> …</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
-font-family:"Courier New"'>}</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>The task
|
|
|
-will initialize during first execution pass and switch to “regular” callback
|
|
|
-execution starting with second pass. There is a delay between first and second
|
|
|
-passes of the task (scheduling period, if defined). In order to execute the
|
|
|
-second pass immediately after initialization first pass, change the above code
|
|
|
-like this:</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
-font-family:"Courier New"'>void workCallbackInit() {</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
-font-family:"Courier New"'> // do your
|
|
|
-initializationstuff here</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
-font-family:"Courier New"'> </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
-font-family:"Courier New"'> // finally assigne the
|
|
|
-main callback function </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
-font-family:"Courier New"'>
|
|
|
-tWork.setCallback(&workCallback);</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
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-font-family:"Courier New"'> tWork.enable();</span></p>
|
|
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-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
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-font-family:"Courier New"'>}</span></p>
|
|
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-
|
|
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-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>The task
|
|
|
-will run initialization first, then immediately second pass, and then switch to
|
|
|
-processing at regular intervals starting with a third pass. </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal> </p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
-
|
|
|
-<ol style='margin-top:0in' start=4 type=1>
|
|
|
- <li class=MsoNormal><b><span style='font-family:"Times New Roman","serif"'>INTERRUP-DRIVEN
|
|
|
- EXECUTION SUPPORT </span></b></li>
|
|
|
-</ol>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>In case
|
|
|
-of interrupt-driven program flow, tasks could be scheduled to run once to
|
|
|
-request asynchronous execution (request), and then re-enabled (restarted) again
|
|
|
-with a different callback function to process the results. </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><b><span style='font-family:"Times New Roman","serif"'>Example</span></b><span
|
|
|
-style='font-family:"Times New Roman","serif"'>: event driven distance
|
|
|
-calculation for ultrasonic pulses. EchoPin #6 triggers pin change interrupts on
|
|
|
-rising and falling edges to determine the length of ultrasonic pulse.</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
-font-family:"Courier New"'>#include <DirectIO.h><br>
|
|
|
-#include <TaskScheduler.h><br>
|
|
|
-#include <PinChangeInt.h><br>
|
|
|
-<br>
|
|
|
-<br>
|
|
|
-#define TRIGGERPIN 5<br>
|
|
|
-#define ECHOPIN 6<br>
|
|
|
-<br>
|
|
|
-Output<TRIGGERPIN> pTrigger;<br>
|
|
|
-Input<ECHOPIN> pEcho;<br>
|
|
|
-<br>
|
|
|
-Scheduler r;<br>
|
|
|
-<br>
|
|
|
-Task tMeasure(1000, -1, &measureCallback);<br>
|
|
|
-Task tDisplay(1000, -1, &displayCallback);<br>
|
|
|
-Task tPing(0, 1, &pingCalcCallback);<br>
|
|
|
-<br>
|
|
|
-<br>
|
|
|
-volatile bool pulseBusy = false;<br>
|
|
|
-volatile bool pulseTimeout = false;<br>
|
|
|
-volatile unsigned long pulseStart = 0;<br>
|
|
|
-volatile unsigned long pulseStop = 0;<br>
|
|
|
-volatile unsigned long pingDistance = 0;<br>
|
|
|
-<br>
|
|
|
-<br>
|
|
|
-void pingTrigger(unsigned long aTimeout) {<br>
|
|
|
- if (pulseBusy) return; // do not trigger if in the middle of a
|
|
|
-pulse<br>
|
|
|
- if (pEcho == HIGH) return; // do not trigger if ECHO pin is high<br>
|
|
|
- <br>
|
|
|
- pulseBusy = true;<br>
|
|
|
- pulseTimeout = false;</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
|
|
|
-margin-left:35.45pt'><span style='font-size:10.0pt;font-family:"Courier New"'><br>
|
|
|
- pTrigger = LOW;<br>
|
|
|
- delayMicroseconds(4);<br>
|
|
|
- pTrigger = HIGH;<br>
|
|
|
-<br>
|
|
|
- tPing.setInterval (aTimeout);<br>
|
|
|
-<br>
|
|
|
- delayMicroseconds(10);<br>
|
|
|
- pTrigger = LOW; </span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
|
|
|
-margin-left:35.45pt'><span style='font-size:10.0pt;font-family:"Courier New"'>
|
|
|
-tPing.restartDelayed(); // timeout countdown starts now</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
-font-family:"Courier New"'>// will start the pulse clock on the rising edge of
|
|
|
-ECHO pin</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
|
|
|
-margin-left:35.45pt'><span style='font-size:10.0pt;font-family:"Courier New"'>
|
|
|
-PCintPort::attachInterrupt(ECHOPIN, &pingStartClock, RISING); <br>
|
|
|
-}<br>
|
|
|
-<br>
|
|
|
-</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
-font-family:"Courier New"'>// Start clock on the <b>rising</b> edge of the
|
|
|
-ultrasonic pulse<br>
|
|
|
-void pingStartClock() {<br>
|
|
|
- pulseStart = micros();<br>
|
|
|
- PCintPort::detachInterrupt(ECHOPIN); // not sure this is necessary<br>
|
|
|
- PCintPort::attachInterrupt(ECHOPIN, &pingStopClock, FALLING); <br>
|
|
|
- tPing.restartDelayed();<br>
|
|
|
-}<br>
|
|
|
-<br>
|
|
|
-// Stop clock on the <b>falling</b> edge of the ultrasonic pulse<br>
|
|
|
-void pingStopClock() {<br>
|
|
|
- pulseStop = micros();<br>
|
|
|
- PcintPort::detachInterrupt(ECHOPIN);</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
|
|
|
-margin-left:35.45pt'><span style='font-size:10.0pt;font-family:"Courier New"'>
|
|
|
-pingDistance = pulseStop - pulseStart;<br>
|
|
|
- pulseBusy = false;<br>
|
|
|
- tPing.disable(); // disable timeout<br>
|
|
|
-}</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
|
|
|
-margin-left:35.45pt'><span style='font-size:10.0pt;font-family:"Courier New"'>//
|
|
|
-Stop clock because of the timeout – the wave did not return<br>
|
|
|
-void pingCalcCallback() {<br>
|
|
|
- if (pulseBusy) {<br>
|
|
|
- pingStopClock();<br>
|
|
|
- }<br>
|
|
|
- pulseTimeout = true;<br>
|
|
|
-}<br>
|
|
|
-<br>
|
|
|
-<br>
|
|
|
-<br>
|
|
|
-// Initial measure callback sets the trigger<br>
|
|
|
-void measureCallback() {<br>
|
|
|
- if (pulseBusy) { // already measuring, try again<br>
|
|
|
- tMeasure.enable();<br>
|
|
|
- return;<br>
|
|
|
- }<br>
|
|
|
- pingTrigger(30); // 30 milliseconds or max range of ~5.1 meters<br>
|
|
|
- tMeasure.setCallback(&measureCallbackWait);<br>
|
|
|
-}</span></p>
|
|
|
-
|
|
|
-<p class=MsoNormal style='margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
|
|
|
-margin-left:35.45pt'><span style='font-size:10.0pt;font-family:"Courier New"'>//
|
|
|
-Wait for the measurement to <br>
|
|
|
-void measureCallbackWait() {<br>
|
|
|
- if (pulseBusy) return;<br>
|
|
|
- tMeasure.setCallback(&measureCallback); <br>
|
|
|
-}<br>
|
|
|
-<br>
|
|
|
-<br>
|
|
|
-bool state = true;<br>
|
|
|
-<br>
|
|
|
-void displayCallback() {<br>
|
|
|
- char d[256];<br>
|
|
|
- <br>
|
|
|
- unsigned long cm = pingDistance * 17 / 100; // cm<br>
|
|
|
- <br>
|
|
|
- snprintf(d, 256, "pulseStart = %8lu\tpulseStop=%8lu\tdistance,
|
|
|
-cm=%8lu", pulseStart, pulseStop, cm);<br>
|
|
|
- Serial.println(d);<br>
|
|
|
- <br>
|
|
|
-}<br>
|
|
|
-<br>
|
|
|
-void setup() {<br>
|
|
|
- // put your setup code here, to run once:<br>
|
|
|
- <br>
|
|
|
- Serial.begin(115200);<br>
|
|
|
- <br>
|
|
|
-<br>
|
|
|
- pTrigger = LOW;<br>
|
|
|
- pEcho = LOW;<br>
|
|
|
- <br>
|
|
|
- r.init();<br>
|
|
|
- r.addTask(tDisplay);<br>
|
|
|
- r.addTask(tMeasure);<br>
|
|
|
- r.addTask(tPing);<br>
|
|
|
- <br>
|
|
|
- r.enableAll();<br>
|
|
|
- tPing.disable();<br>
|
|
|
-}<br>
|
|
|
-<br>
|
|
|
-void loop() {<br>
|
|
|
- // put your main code here, to run repeatedly:<br>
|
|
|
- r.execute();<br>
|
|
|
-}</span></p>
|
|
|
-
|
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-</div>
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-
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+.MsoChpDefault
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+ {font-size:10.0pt;}
|
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+@page WordSection1
|
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|
+ {size:8.5in 11.0in;
|
|
|
+ margin:56.7pt 56.7pt 56.7pt 56.7pt;}
|
|
|
+div.WordSection1
|
|
|
+ {page:WordSection1;}
|
|
|
+ /* List Definitions */
|
|
|
+ ol
|
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|
+ {margin-bottom:0in;}
|
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+ul
|
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+ {margin-bottom:0in;}
|
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+-->
|
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+</style>
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+
|
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+</head>
|
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+
|
|
|
+<body bgcolor=white lang=EN-US style='line-break:strict'>
|
|
|
+
|
|
|
+<div class=WordSection1>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>Task Scheduler – cooperative multitasking for Arduino microcontrollers</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>Version 1.51: 2015-09-20</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>REQUIREMENT</b>:</p>
|
|
|
+
|
|
|
+<p class=MsoNormal>A lightweight implementation of the task scheduling
|
|
|
+supporting:</p>
|
|
|
+
|
|
|
+<ol style='margin-top:0in' start=1 type=1>
|
|
|
+ <li class=MsoNormal>execution period (n times per second)</li>
|
|
|
+ <li class=MsoNormal>number of iterations (n times)</li>
|
|
|
+ <li class=MsoNormal>execution of tasks in predefined sequence</li>
|
|
|
+ <li class=MsoNormal>dynamic change of the execution parameters for both tasks
|
|
|
+ and execution schedule</li>
|
|
|
+ <li class=MsoNormal>power saving via entering IDLE sleep mode if no tasks are
|
|
|
+ scheduled to run</li>
|
|
|
+</ol>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>IDEA</b>:</p>
|
|
|
+
|
|
|
+<p class=MsoNormal>“Task” is a container concept that links together:</p>
|
|
|
+
|
|
|
+<ol style='margin-top:0in' start=1 type=1>
|
|
|
+ <li class=MsoNormal>Execution interval</li>
|
|
|
+ <li class=MsoNormal>Number of execution iterations</li>
|
|
|
+ <li class=MsoNormal>A piece of code performing the task activities (callback
|
|
|
+ function)</li>
|
|
|
+</ol>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal>Tasks are linked into execution chains, which are processed
|
|
|
+by the “Scheduler” in the order they are linked.</p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal>Tasks are responsible for supporting cooperative
|
|
|
+multitasking by being “good neighbors”, i.e., running their callback functions
|
|
|
+in a non-blocking way and releasing control as soon as possible. </p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal>“Scheduler” is executing Tasks' callback functions in the
|
|
|
+order the tasks were added to the chain, from first to last. Scheduler stops
|
|
|
+and exists after processing the chain once in order to allow other statements
|
|
|
+in the main code of <b>loop()</b> function to run. This a “scheduling
|
|
|
+pass”.</p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal>If compiled with <span style='font-family:"Courier New"'>_TASK_SLEEP_ON_IDLE_RUN</span>
|
|
|
+enabled, the scheduler will place processor into IDLE sleep mode (for
|
|
|
+approximately 1 ms, as the timer interrupt will wake it up), after what is
|
|
|
+determined to be an “idle” pass. An Idle Pass is a pass through the chain when
|
|
|
+no Tasks were scheduled to run their callback functions. This is done to avoid
|
|
|
+repetitive empty passes through the chain when no tasks need to be executed. If
|
|
|
+any of the tasks in the chain always requires immediate execution (aInterval =
|
|
|
+0), then there will be no end-of-pass delay.</p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>Note: </b>Task Scheduler uses <b>millis()</b> to
|
|
|
+determine if tasks are ready to be invoked. Therefore, if you put your device
|
|
|
+to any “deep” sleep mode disabling timer interrupts, the <b>millis()</b> count
|
|
|
+will be suspended, leading to effective suspension of scheduling. Upon wake up,
|
|
|
+active tasks need to be re-enabled, which will effectively reset their internal
|
|
|
+time scheduling variables to the new value of <b>millis(). </b>Time spent in
|
|
|
+deep sleep mode should be considered “frozen”, i.e., if a task was scheduled to
|
|
|
+run in 1 second from now, and device was put to sleep for 5 minutes, upon wake
|
|
|
+up, the task will still be scheduled 1 second from the time of wake up.
|
|
|
+Executing <b>enable() </b>function on this tasks will make it run as soon as
|
|
|
+possible. This is a concern only for tasks which are required to run in a truly
|
|
|
+periodical manner (in absolute time terms). </p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>COMPILE PARAMETERS:</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal>This library could be compiled with several options. </p>
|
|
|
+
|
|
|
+<p class=MsoNormal>These parameters must be defined before inclusion of the
|
|
|
+library header file into the sketch.</p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal>#define <b>_TASK_TIMECRITICAL</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal>...will compile the library with time critical tracking
|
|
|
+option enabled.</p>
|
|
|
+
|
|
|
+<p class=MsoNormal>Time critical option keeps track where next execution time
|
|
|
+of the task falls, and makes it available via API through Task::<b> getOverrun()
|
|
|
+</b>function. If <b>getOverrun </b>returns a negative value, this Task’s next
|
|
|
+execution time is in the past, and task is behind schedule. This most probably
|
|
|
+means that either task’s callback function runtime is too long, or the
|
|
|
+execution interval is too short (then schedule is too aggressive).</p>
|
|
|
+
|
|
|
+<p class=MsoNormal>A positive value indicates that task is on schedule, and
|
|
|
+callback functions have enough time to finish before the next scheduled pass. </p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal>#define <b>_TASK_SLEEP_ON_IDLE_RUN</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal>...will compile the library with the <b>sleep</b> option
|
|
|
+enabled (AVR boards only).</p>
|
|
|
+
|
|
|
+<p class=MsoNormal>When enabled, scheduler will put the microcontroller into <b>SLEEP_MODE_IDLE</b>
|
|
|
+state if none of the tasks’ callback functions were activated during pass. <b>IDLE</b>
|
|
|
+state is interrupted by timers once every 1 ms. Helps conserve power. Device
|
|
|
+in SLEEP_MODE_IDLE wakes up to all hardware and timer interrupts, so scheduling
|
|
|
+is kept current.</p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>NOTE: above parameters are DISABLED by default, and need
|
|
|
+to be explicitly enabled.</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>API DOCUMENTATION:</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>TASKS:</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal>CREATION:</p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>Task();</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>Default constructor. </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>Takes no parameters and creates
|
|
|
+a task that could be scheduled to run at every scheduling pass indefinitely,
|
|
|
+but does not have a callback function defined, so no execution will actually
|
|
|
+take place. </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>All tasks are created <b>disabled</b>
|
|
|
+by default.</p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='page-break-after:avoid'><b>Task(unsigned long aInterval,
|
|
|
+long aIterations, void (*aCallback)(), Scheduler* aScheduler, bool aEnable);</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>Constructor with parameters. </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>Creates a task that is scheduled
|
|
|
+to run every <aInterval> milliseconds, <aIterations> times,
|
|
|
+executing <aCallback> function on every pass. </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:71.45pt;text-indent:-.25in'>1.<span
|
|
|
+style='font-size:7.0pt;font-family:"Times New Roman","serif"'>
|
|
|
+</span>aInterval is in milliseconds</p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:71.45pt;text-indent:-.25in'>2.<span
|
|
|
+style='font-size:7.0pt;font-family:"Times New Roman","serif"'>
|
|
|
+</span>aIteration in number of times, -1 for indefinite execution<br>
|
|
|
+<b>Note: </b>Tasks do not remember the number of iteration set initially. After
|
|
|
+the iterations are done, internal iteration counter is 0. If you need to
|
|
|
+perform another set of iterations, you need to set the number of iterations
|
|
|
+again. <br>
|
|
|
+<b>Note: </b>Tasks which performed all their iterations remain active. </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:71.45pt;text-indent:-.25in'>3.<span
|
|
|
+style='font-size:7.0pt;font-family:"Times New Roman","serif"'>
|
|
|
+</span>aCallback is a pointer to a void function without parameters</p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:71.45pt;text-indent:-.25in'>4.<span
|
|
|
+style='font-size:7.0pt;font-family:"Times New Roman","serif"'>
|
|
|
+</span>aScheduler – <b>optional</b> reference to existing scheduler. If
|
|
|
+supplied (not NULL) this task will be appended to the task chain of the current
|
|
|
+scheduler). <b>Default=NULL</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:71.45pt;text-indent:-.25in'>5.<span
|
|
|
+style='font-size:7.0pt;font-family:"Times New Roman","serif"'>
|
|
|
+</span>aEnable – <b>optional</b>. Value of <b>true </b>will create task
|
|
|
+enabled. <b>Default = false</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>All tasks are created <b>disabled</b>
|
|
|
+by default (unless aEnable = true). You have to explicitly enable the task for
|
|
|
+execution.</p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>Enabled task is scheduled for execution
|
|
|
+immediately. Enable tasks with delay (standard execution interval or specific
|
|
|
+execution interval) in order to defer first run of the task.</p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>INFORMATION</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>The following 3 “getter”
|
|
|
+functions return task status (enabled/disabled), execution interval in
|
|
|
+milliseconds, number of <b><i>remaining</i></b> iterations. </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><b>bool isEnabled() </b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><b>unsigned long getInterval()</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><b>long getIterations() </b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><b> </b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>long getOverrun()</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>If library is compiled with <span
|
|
|
+style='font-family:"Courier New"'>_TASK_TIMECRITICAL</span> enabled, tasks are
|
|
|
+monitored for “long running” scenario. A “long running” task is a task that
|
|
|
+does not finish processing its callback functions quickly, and thus creates a
|
|
|
+situation for itself and other tasks where they don't run on a scheduled
|
|
|
+interval, but rather “catch up” and are behind. When task scheduler sets
|
|
|
+the next execution target time, it adds Task's execution interval to the
|
|
|
+previously scheduled execution time:</p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>
|
|
|
+<b>next execution time = previous execution time + task execution interval</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>If <b>next execution time</b> happens
|
|
|
+to be already in the past (<b>next execution time</b> < <b>millis()</b>), then
|
|
|
+task is considered <b><i>overrun</i></b>. <b>GetOverrun</b> function returns
|
|
|
+number of milliseconds between next execution time and current time. If the <b>value
|
|
|
+is negative</b>, the task is overrun by that many milliseconds. </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>Positive value indicate number
|
|
|
+of milliseconds of slack this task has for execution purposes. </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>bool isFirstIteration()</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>bool isLastIteration()</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>For tasks with a defined number
|
|
|
+of iterations, indicates whether current pass is a first or a last iteration of
|
|
|
+the task (respectively). </p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='page-break-after:avoid'><b>CONTROL:</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>void enable();</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>Enables the task, and schedules
|
|
|
+it for immediate execution (without delay) at this or next scheduling pass
|
|
|
+depending on when the task was enabled. Scheduler will execute the next pass
|
|
|
+without any delay because there is a task which was enabled and requires
|
|
|
+execution. </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>void delay();</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>Schedules the task for execution
|
|
|
+after a delay (aInterval), but does not change the enabled/disabled status of
|
|
|
+the task. </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><b> </b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>void enableDelayed();</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>Enables the task, and schedules
|
|
|
+it for execution after a delay (aInterval). </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>void enableDelayed (unsigned long aDelay);</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>Enables the task, and schedules
|
|
|
+it for execution after a specific delay (aDelay, which maybe different from aInterval).
|
|
|
+</p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>void restart();</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>For tasks with limited number of
|
|
|
+iterations only, <b>restart</b> function will re-enable the task, set the
|
|
|
+number of iterations back to when the task was created and and schedule the
|
|
|
+task for execution as soon as possible.</p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>void restartDelayed (unsigned long aDelay);</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>Same as <b>restart() </b>function,
|
|
|
+with the only difference being that Task is scheduled to run first iteration
|
|
|
+after a delay = <b>aDelay</b> milliseconds.</p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b> </b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>void disable();</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>Disables the task. Scheduler
|
|
|
+will not execute this task any longer, even if it remains in the chain. Task
|
|
|
+can be later re-enabled for execution. </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>void disableOnLastIteration (bool aBool);</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>Controls iterative task behavior
|
|
|
+on the last iteration. If <b>aBool</b> is <b>true</b> task will be disabled
|
|
|
+after last iteration. If <b>aBool</b> is <b>false</b>, task will remain active
|
|
|
+(but not invoked until new number of iterations is set)</p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>void set(unsigned long aInterval, long aIterations, void (*aCallback)());</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>Allows dynamic control of all
|
|
|
+task execution parameters in one function call. If task being modified is
|
|
|
+active, it will be scheduled for execution immediately. </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal>Next three “setter” functions allow changes of individual
|
|
|
+task execution control parameters. </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><b>void setInterval (unsigned
|
|
|
+long aInterval) </b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><b>void setIterations (long aIterations)
|
|
|
+</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><b>void setCallback (void
|
|
|
+(*aCallback)()) </b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>Note: </b>Next execution time calculation takes place <b>after</b>
|
|
|
+the callback function is called, so new interval will be used immediately by
|
|
|
+the scheduler. For the situations when one task is changing the interval
|
|
|
+parameter for the other, <b>setInterval</b> function calls <b>delay </b>explicitly
|
|
|
+to guarantee schedule change, however it <b>does not </b>enable the task if
|
|
|
+task is disabled. If task being modified is active, <b>setIterations </b>will
|
|
|
+make the task be scheduled for execution immediately.</p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b> </b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>TASK SCHEDULER:</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>CREATION:</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-bottom:12.0pt'><b>Scheduler()</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>Default constructor. </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>Takes no parameters. Creates
|
|
|
+task scheduler with default parameters and an empty task queue. </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>void init()</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>Initializes the task queue and
|
|
|
+scheduler parameters, Executed as part of constructor, so don't need to be
|
|
|
+explicitly called after creation.</p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><b>Note: </b>be default (if
|
|
|
+compiled with <span style='font-family:"Courier New"'>_TASK_TIMECRITICAL</span>
|
|
|
+enabled) scheduler is allowed to put processor to IDLE sleep mode. If this
|
|
|
+behavior was changed via <b>allowSleep() </b>function, <b>inti() </b>will <b>NOT</b>
|
|
|
+reset allow sleep particular parameter. </p>
|
|
|
+
|
|
|
+<p class=MsoNormal><br>
|
|
|
+<b>void addTask(Task& aTask)</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>Adds task aTask to the execution
|
|
|
+queue (or chain) of tasks by appending it to the end of the chain. If two tasks
|
|
|
+are scheduled for execution, the sequence will match the order tasks are
|
|
|
+appended to the chain. However, in reality, due to different timing of task
|
|
|
+execution, the actual order will be different. </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><b>Note: </b>Currently, changing
|
|
|
+the execution dynamically is not supported. </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>If you need to reorder the queue
|
|
|
+– initialize the scheduler and re-add the tasks in a different order. </p>
|
|
|
+
|
|
|
+<p class=MsoNormal><br>
|
|
|
+<b>void deleteTask(Task& aTask)</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>Deletes task aTask from the
|
|
|
+execution chain. The chain of remaining tasks is linked together (i.e</p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>if original task chain is 1 →
|
|
|
+2 → 3 → 4, deleting 3 will result in 1 → 2 → 4).</p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><b>Note: </b>it is not required
|
|
|
+to delete a task from the chain. A disabled task will not be executed anyway,
|
|
|
+but you save a few microseconds per scheduling pass by deleting it, since it is
|
|
|
+not even considered for execution. </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>An example of proper use of this
|
|
|
+function would be running some sort of <b>initialize</b> task in the chain, and
|
|
|
+then deleting it from the chain since it only needs to run once. </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>void allowSleep(bool aState) </b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>Available in API only if compiled
|
|
|
+with <span style='font-family:"Courier New"'>_TASK_TIMECRITICAL</span> enabled.
|
|
|
+Controls whether scheduler is allowed (<b>aState =true</b>), or not (<b>aState =false</b>)
|
|
|
+to put processor into IDLE sleep mode in case not tasks are scheduled to run.</p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>The <b>default</b> behavior of
|
|
|
+scheduler upon creation is to allow sleep mode. </p>
|
|
|
+
|
|
|
+<p class=MsoNormal><br>
|
|
|
+<b>void enableAll()</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b>void disableAll()</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>enables and disables
|
|
|
+(respectively) all tasks in the chain. Convenient if your need to
|
|
|
+enable/disable majority of the tasks (i.e. disable all and then enable one). </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-bottom:12.0pt'><br>
|
|
|
+<b>Task& currentTask()</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>Returns reference to the task,
|
|
|
+currently executing via <b>execute()</b> loop. Could be used by callback
|
|
|
+functions to identify which of the </p>
|
|
|
+
|
|
|
+<p class=MsoNormal><br>
|
|
|
+<b>void execute()</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'>Executes one scheduling pass,
|
|
|
+including end-of-pass sleep. This function typically placed inside the <b>loop()</b>
|
|
|
+function of the sketch. Since <b>execute</b> exits after every pass, you can
|
|
|
+put additional statements after <b>execute</b> inside the <b>loop()</b> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='page-break-after:avoid'><b>IMPLEMENTATION SCENARIOS
|
|
|
+AND IDEAS:</b></p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<ol style='margin-top:0in' start=1 type=1>
|
|
|
+ <li class=MsoNormal><b>EVENT DRIVEN PROGRAMMING</b></li>
|
|
|
+</ol>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal>Each of the processes of your application becomes a separate
|
|
|
+and distinct programming area, which may or may not interact and control each
|
|
|
+other. </p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal>Example: </p>
|
|
|
+
|
|
|
+<p class=MsoNormal>In a plant watering system you need to measure soil
|
|
|
+humidity, control pump and display the results</p>
|
|
|
+
|
|
|
+<p class=MsoNormal>Each of the areas becomes a task:</p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
|
|
|
+margin-left:35.45pt'><span style='font-size:10.0pt;font-family:"Courier New"'>Task
|
|
|
+<b>tMeasure</b> (TMEASURE_INTERVAL*SECOND, -1, &measureCallback);<br>
|
|
|
+Task <b>tWater</b> (TWATER_INTERVAL*SECOND, RETRIES,
|
|
|
+&waterCallback);<br>
|
|
|
+Task <b>tDisplay</b> (TDISPLAY_INTERVAL*SECOND, -1, &displayCallback); </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
|
|
|
+margin-left:35.45pt'><span style='font-size:10.0pt;font-family:"Courier New"'>Scheduler
|
|
|
+<b>taskManager</b>;</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal>Further, once you turn on the pump, you keep it running for
|
|
|
+TWATER_INTERVAL interval and then turn it off. Turning off a pump is also a
|
|
|
+task which only needs to run once for every time the pump is turned on:</p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
|
|
|
+margin-left:35.45pt'><span style='font-size:10.0pt;font-family:"Courier New"'>Task
|
|
|
+<b>tWaterOff</b> (WATERTIME*SECOND, 1,</span><span style='font-family:"Courier New"'>
|
|
|
+&waterOffCallback);</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal>Example of the callback function:</p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
+font-family:"Courier New"'>void waterOffCallback() {<br>
|
|
|
+ motorOff();<br>
|
|
|
+ tWater.enableDelayed();<br>
|
|
|
+}</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
+font-family:"Courier New"'> </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
+font-family:"Courier New"'>or</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
+font-family:"Courier New"'> </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
+font-family:"Courier New"'>void waterCallback() {<br>
|
|
|
+ if (tWater.getIterations()) {</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
+font-family:"Courier New"'>// If this is not the last iteration = turn the pump
|
|
|
+on<br>
|
|
|
+ motorOn();<br>
|
|
|
+ tWaterOff.set(parameters.watertime * SECOND, 1,
|
|
|
+&waterOffCallback);<br>
|
|
|
+ tWaterOff.enableDelayed();<br>
|
|
|
+ return;<br>
|
|
|
+ }</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
+font-family:"Courier New"'>// We could not reach target humidity – something is
|
|
|
+wrong<br>
|
|
|
+ motorOff;<br>
|
|
|
+ taskManager.disableAll();<br>
|
|
|
+ tError.enable();<br>
|
|
|
+}</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Courier New"'> </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>Your
|
|
|
+sample <b>setup</b>() and <b>loop</b>() (partially) are as follows. </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b><span style='font-family:"Times New Roman","serif"'>Note:
|
|
|
+</span></b><span style='font-family:"Times New Roman","serif"'>please note that
|
|
|
+tWater is <b>not</b> activated during setup(). It is activated by tMeasure
|
|
|
+callback once the watering conditions are met. </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>
|
|
|
+</span><span style='font-family:"Courier New"'>setup()</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Courier New"'>
|
|
|
+ ...</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
|
|
|
+margin-left:35.45pt'><span style='font-family:"Courier New"'>
|
|
|
+tWater.setIterations(parameters.retries);<br>
|
|
|
+ tWaterOff.setInterval(parameters.watertime * SECOND);<br>
|
|
|
+<br>
|
|
|
+<br>
|
|
|
+ taskManager.init();<br>
|
|
|
+ taskManager.addTask(tMeasure);<br>
|
|
|
+ taskManager.addTask(tDisplay);<br>
|
|
|
+ taskManager.addTask(tWater);<br>
|
|
|
+ taskManager.addTask(tWaterOff);<br>
|
|
|
+ <br>
|
|
|
+ tMeasure.enable();<br>
|
|
|
+ tDisplay.enable();<br>
|
|
|
+<br>
|
|
|
+ currentHumidity = measureHumidity();<br>
|
|
|
+}<br>
|
|
|
+<br>
|
|
|
+<br>
|
|
|
+void loop ()<br>
|
|
|
+{<br>
|
|
|
+ taskManager.execute();<br>
|
|
|
+}</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
|
|
|
+margin-left:35.45pt'> </p>
|
|
|
+
|
|
|
+<ol style='margin-top:0in' start=2 type=1>
|
|
|
+ <li class=MsoNormal><b><span style='font-family:"Times New Roman","serif"'>“NATIVE”
|
|
|
+ SUPPORT FOR FINITE STATE MACHINE</span></b></li>
|
|
|
+</ol>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>Define
|
|
|
+“states” as callback function or functions. Each callback function executes
|
|
|
+activities specific to a “state” and then “transitions” to the next state by
|
|
|
+assigning next callback function to the task. </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>Transition
|
|
|
+from one state to the next is achieved by setting next callback function at the
|
|
|
+end of preceding one. </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b><span style='font-family:"Times New Roman","serif"'>Note:
|
|
|
+</span></b><span style='font-family:"Times New Roman","serif"'>do not call the
|
|
|
+next callback function. Let the schedule take care of that during the next
|
|
|
+pass. (Thus letting other tasks run). </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>Example:
|
|
|
+Blinking LED 2 times a second could be achieved this way</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>Task
|
|
|
+tLedBlinker (500, -1, &ledOnCallback);</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>Scheduler
|
|
|
+taskManager;</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'> </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>void
|
|
|
+ledOnCallback() {</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>
|
|
|
+turnLedOn();</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>
|
|
|
+tLedBlinker.setCallback(&ledOffCallback);</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>}</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'> </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>void
|
|
|
+ledOffCallback() {</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>
|
|
|
+turnLedOff();</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>
|
|
|
+tLedBlinker.setCallback(&ledOnCallback);</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>}</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'> </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>setup()
|
|
|
+{</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>
|
|
|
+taskManager.init();<br>
|
|
|
+ taskManager.addTask(tLedBlinker);</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>
|
|
|
+</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>
|
|
|
+tLedBlinker.enable();</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>}</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'> </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>loop
|
|
|
+() {</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Courier New"'>
|
|
|
+taskManager.execute();</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
|
|
|
+margin-left:35.45pt'><span style='font-family:"Courier New"'>}</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>Obviously
|
|
|
+the example is simple, but gives the idea of how the tasks could be used to go
|
|
|
+through states.</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
+
|
|
|
+<ol style='margin-top:0in' start=3 type=1>
|
|
|
+ <li class=MsoNormal><b><span style='font-family:"Times New Roman","serif"'>MULTIPLE
|
|
|
+ POSSIBLE CALLBACKS FOR TASK</span></b></li>
|
|
|
+</ol>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>There may
|
|
|
+be a need to select an option for callback function based on certain criteria,
|
|
|
+or randomly. </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>You can
|
|
|
+achieve that by defining an array of callback function pointers and selecting
|
|
|
+one based on the criteria you need. </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>Example:
|
|
|
+when a robot detects an obstacle, it may go left, right backwards, etc. Each of
|
|
|
+the “directions” or “behaviors” are represented by a different callback
|
|
|
+function. </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>Another
|
|
|
+example of using multiple callbacks:</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>You may
|
|
|
+need to “initialize” variables for a particular task.</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>In this
|
|
|
+case, define a tasks with two callbacks:</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
+font-family:"Courier New"'>Task <b>tWork</b> (T_INTERVAL, -1,
|
|
|
+&workCallbackInit);</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
+font-family:"Courier New"'>…</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
+font-family:"Courier New"'>void workCallbackInit() {</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
+font-family:"Courier New"'> // do your
|
|
|
+initializationstuff here</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
+font-family:"Courier New"'> </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
+font-family:"Courier New"'> // finally assigne
|
|
|
+the main callback function </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
+font-family:"Courier New"'>
|
|
|
+tWork.setCallback(&workCallback);</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
+font-family:"Courier New"'>}</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
+font-family:"Courier New"'>void workCallback() {</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
+font-family:"Courier New"'> // main callback
|
|
|
+function</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
+font-family:"Courier New"'> …</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
+font-family:"Courier New"'>}</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>The task
|
|
|
+will initialize during first execution pass and switch to “regular” callback
|
|
|
+execution starting with second pass. There is a delay between first and second
|
|
|
+passes of the task (scheduling period, if defined). In order to execute the
|
|
|
+second pass immediately after initialization first pass, change the above code
|
|
|
+like this:</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
+font-family:"Courier New"'>void workCallbackInit() {</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
+font-family:"Courier New"'> // do your
|
|
|
+initializationstuff here</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
+font-family:"Courier New"'> </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
+font-family:"Courier New"'> // finally assigne the
|
|
|
+main callback function </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
+font-family:"Courier New"'>
|
|
|
+tWork.setCallback(&workCallback);</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
+font-family:"Courier New"'> tWork.enable();</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
+font-family:"Courier New"'>}</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>The task
|
|
|
+will run initialization first, then immediately second pass, and then switch to
|
|
|
+processing at regular intervals starting with a third pass. </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal> </p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
+
|
|
|
+<ol style='margin-top:0in' start=4 type=1>
|
|
|
+ <li class=MsoNormal><b><span style='font-family:"Times New Roman","serif"'>INTERRUP-DRIVEN
|
|
|
+ EXECUTION SUPPORT </span></b></li>
|
|
|
+</ol>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'>In case
|
|
|
+of interrupt-driven program flow, tasks could be scheduled to run once to
|
|
|
+request asynchronous execution (request), and then re-enabled (restarted) again
|
|
|
+with a different callback function to process the results. </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><b><span style='font-family:"Times New Roman","serif"'>Example</span></b><span
|
|
|
+style='font-family:"Times New Roman","serif"'>: event driven distance
|
|
|
+calculation for ultrasonic pulses. EchoPin #6 triggers pin change interrupts on
|
|
|
+rising and falling edges to determine the length of ultrasonic pulse.</span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal><span style='font-family:"Times New Roman","serif"'> </span></p>
|
|
|
+
|
|
|
+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
|
|
|
+font-family:"Courier New"'>#include <DirectIO.h><br>
|
|
|
+#include <TaskScheduler.h><br>
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+#include <PinChangeInt.h><br>
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+<br>
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+<br>
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+#define TRIGGERPIN 5<br>
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+#define ECHOPIN 6<br>
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+<br>
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+Output<TRIGGERPIN> pTrigger;<br>
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+Input<ECHOPIN> pEcho;<br>
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+<br>
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+Scheduler r;<br>
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+<br>
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+Task tMeasure(1000, -1, &measureCallback);<br>
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+Task tDisplay(1000, -1, &displayCallback);<br>
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+Task tPing(0, 1, &pingCalcCallback);<br>
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+<br>
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+<br>
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+volatile bool pulseBusy = false;<br>
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+volatile bool pulseTimeout = false;<br>
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+volatile unsigned long pulseStart = 0;<br>
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+volatile unsigned long pulseStop = 0;<br>
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+volatile unsigned long pingDistance = 0;<br>
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+<br>
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+<br>
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+void pingTrigger(unsigned long aTimeout) {<br>
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+ if (pulseBusy) return; // do not trigger if in the middle of a
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+pulse<br>
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+ if (pEcho == HIGH) return; // do not trigger if ECHO pin is high<br>
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+ <br>
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+ pulseBusy = true;<br>
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+ pulseTimeout = false;</span></p>
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+
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+<p class=MsoNormal style='margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
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+margin-left:35.45pt'><span style='font-size:10.0pt;font-family:"Courier New"'><br>
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+ pTrigger = LOW;<br>
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+ delayMicroseconds(4);<br>
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+ pTrigger = HIGH;<br>
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+<br>
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+ tPing.setInterval (aTimeout);<br>
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+<br>
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+ delayMicroseconds(10);<br>
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+ pTrigger = LOW; </span></p>
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+
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+<p class=MsoNormal style='margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
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+margin-left:35.45pt'><span style='font-size:10.0pt;font-family:"Courier New"'>
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+tPing.restartDelayed(); // timeout countdown starts now</span></p>
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+
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+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
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+font-family:"Courier New"'>// will start the pulse clock on the rising edge of
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+ECHO pin</span></p>
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+
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+<p class=MsoNormal style='margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
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+margin-left:35.45pt'><span style='font-size:10.0pt;font-family:"Courier New"'>
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+PCintPort::attachInterrupt(ECHOPIN, &pingStartClock, RISING); <br>
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+}<br>
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+<br>
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+</span></p>
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+
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+<p class=MsoNormal style='margin-left:35.45pt'><span style='font-size:10.0pt;
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+font-family:"Courier New"'>// Start clock on the <b>rising</b> edge of the
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+ultrasonic pulse<br>
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+void pingStartClock() {<br>
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+ pulseStart = micros();<br>
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+ PCintPort::detachInterrupt(ECHOPIN); // not sure this is necessary<br>
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+ PCintPort::attachInterrupt(ECHOPIN, &pingStopClock, FALLING); <br>
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+ tPing.restartDelayed();<br>
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+}<br>
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+<br>
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+// Stop clock on the <b>falling</b> edge of the ultrasonic pulse<br>
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+void pingStopClock() {<br>
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+ pulseStop = micros();<br>
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+ PcintPort::detachInterrupt(ECHOPIN);</span></p>
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+
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+<p class=MsoNormal style='margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
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+margin-left:35.45pt'><span style='font-size:10.0pt;font-family:"Courier New"'>
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+pingDistance = pulseStop - pulseStart;<br>
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+ pulseBusy = false;<br>
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+ tPing.disable(); // disable timeout<br>
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+}</span></p>
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+
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+<p class=MsoNormal style='margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
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+margin-left:35.45pt'><span style='font-size:10.0pt;font-family:"Courier New"'>//
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+Stop clock because of the timeout – the wave did not return<br>
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+void pingCalcCallback() {<br>
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+ if (pulseBusy) {<br>
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+ pingStopClock();<br>
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+ }<br>
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+ pulseTimeout = true;<br>
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+}<br>
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+<br>
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+<br>
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+<br>
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+// Initial measure callback sets the trigger<br>
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+void measureCallback() {<br>
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+ if (pulseBusy) { // already measuring, try again<br>
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+ tMeasure.enable();<br>
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+ return;<br>
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+ }<br>
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+ pingTrigger(30); // 30 milliseconds or max range of ~5.1 meters<br>
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+ tMeasure.setCallback(&measureCallbackWait);<br>
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+}</span></p>
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+
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+<p class=MsoNormal style='margin-top:0in;margin-right:0in;margin-bottom:12.0pt;
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+margin-left:35.45pt'><span style='font-size:10.0pt;font-family:"Courier New"'>//
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+Wait for the measurement to <br>
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+void measureCallbackWait() {<br>
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+ if (pulseBusy) return;<br>
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+ tMeasure.setCallback(&measureCallback); <br>
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+}<br>
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+<br>
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+<br>
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+bool state = true;<br>
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+<br>
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+void displayCallback() {<br>
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+ char d[256];<br>
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+ <br>
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+ unsigned long cm = pingDistance * 17 / 100; // cm<br>
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+ <br>
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+ snprintf(d, 256, "pulseStart = %8lu\tpulseStop=%8lu\tdistance,
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+cm=%8lu", pulseStart, pulseStop, cm);<br>
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+ Serial.println(d);<br>
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+ <br>
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+}<br>
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+<br>
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+void setup() {<br>
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+ // put your setup code here, to run once:<br>
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+ <br>
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+ Serial.begin(115200);<br>
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+ <br>
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+<br>
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+ pTrigger = LOW;<br>
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+ pEcho = LOW;<br>
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+ <br>
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+ r.init();<br>
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+ r.addTask(tDisplay);<br>
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+ r.addTask(tMeasure);<br>
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+ r.addTask(tPing);<br>
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+ <br>
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+ r.enableAll();<br>
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+ tPing.disable();<br>
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+}<br>
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+<br>
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+void loop() {<br>
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+ // put your main code here, to run repeatedly:<br>
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+ r.execute();<br>
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+}</span></p>
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+
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+</div>
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+
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+</body>
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+
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+</html>
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Anatoli Arkhipenko