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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta http-equiv="Content-Type" content="text/html;charset=UTF-8"><title>YAVRTOS: </title><link href="doxygen.css" rel="stylesheet" type="text/css"><link href="tabs.css" rel="stylesheet" type="text/css"></head><body><!-- Generated by Doxygen 1.5.4 --><div class="tabs"> <ul> <li><a href="index.html"><span>Main Page</span></a></li> <li><a href="modules.html"><span>Modules</span></a></li> <li><a href="annotated.html"><span>Data Structures</span></a></li> <li><a href="files.html"><span>Files</span></a></li> <li><a href="pages.html"><span>Related Pages</span></a></li> </ul></div>In this example, we will flash two LEDs connected to port A at different rates.<p><div class="fragment"><pre class="fragment"><span class="preprocessor">#include "<a class="code" href="task_8h.html">task.h</a>"</span><span class="preprocessor">#include <stdint.h></span><span class="preprocessor">#include <avr/interrupt.h></span><span class="preprocessor">#include <avr/io.h></span><span class="preprocessor">#include <avr/sleep.h></span><span class="comment">// A semaphore that we will increment at every tick</span><span class="keyword">static</span> <a class="code" href="structsemaphore__t.html" title="Structure describing a semaphore.">semaphore_t</a> tick;<span class="comment">// We will also create a mutex for port A, as both tasks will be using it potentially "simultaneously"</span><span class="keyword">static</span> <a class="code" href="structmutex__t.html" title="A structure describing a mutex.">mutex_t</a> porta_mutex;<span class="comment">// This is our first task - blinking port A bit 0 once every 200 ticks</span><span class="keywordtype">void</span> blink1(<span class="keywordtype">void</span> *p) { <span class="keywordflow">while</span> (1) { <span class="comment">// Obtain a lock on the port A mutex</span> <a class="code" href="group__mutex.html#gdff77e0b451c30c07d2990e669f937c5" title="Lock on a mutex.">lock_on</a>(&porta_mutex); <span class="comment">// OK - port A is now all ours, so blink the LED</span> PORTA ^= 0x01; <span class="comment">// Release our hold on the port A mutex</span> <a class="code" href="group__mutex.html#g327f419711064b7407f6f47011221cc4" title="Unlock a mutex.">lock_off</a>(&porta_mutex); <span class="comment">// Now, suspend this task for another 200 ticks</span> <a class="code" href="group__semaphore.html#g291edcd883e2d0bc17f85419e21069ff" title="Wait for a semaphore to increment its value by a certain amount.">wait_for_increment_of</a>(&tick, 200); }}<span class="comment">// This is our second task - blinking port A bit 1 once every 280 ticks</span><span class="keywordtype">void</span> blink2(<span class="keywordtype">void</span> *p) { <span class="keywordflow">while</span> (1) { <span class="comment">// Obtain a lock on the port A mutex</span> <a class="code" href="group__mutex.html#gdff77e0b451c30c07d2990e669f937c5" title="Lock on a mutex.">lock_on</a>(&porta_mutex); <span class="comment">// OK - port A is now all ours, so blink the LED</span> PORTA ^= 0x02; <span class="comment">// Release our hold on the port A mutex</span> <a class="code" href="group__mutex.html#g327f419711064b7407f6f47011221cc4" title="Unlock a mutex.">lock_off</a>(&porta_mutex); <span class="comment">// Now, suspend this task for another 280 ticks</span> <a class="code" href="group__semaphore.html#g291edcd883e2d0bc17f85419e21069ff" title="Wait for a semaphore to increment its value by a certain amount.">wait_for_increment_of</a>(&tick, 280); }}<span class="comment">// This is our idle task - the task that runs when all others are suspended.</span><span class="comment">// We sleep the CPU - the CPU will automatically awake when the tick interrupt occurs</span><span class="keywordtype">void</span> idle_task(<span class="keywordtype">void</span> *p) { sleep_enable(); sei(); sleep_cpu(); <span class="comment">// This task cannot be stopped, so it is automatically re-started whenever it tries to exit</span>}<span class="comment">// This is a function that runs every tick interrupt - we use it to increment the tick semaphore value by one</span>uint8_t tick_interrupt() { <a class="code" href="group__semaphore.html#g3cd218588dccb32b5b9072c7a75fb008" title="Increment the value of a semaphore by the given amount.">increment_semaphore_by</a>(&tick,1); <span class="comment">// We want a task switch to ALWAYS occur - it is part of the definition of the tick interrupt!</span> <span class="keywordflow">return</span> 1;}<span class="comment">// Setup the TIMER1_COMPA interrupt - it will be our tick interrupt</span><a class="code" href="group__isr.html#g3d04938242a5060aac8a64b72c055eb0" title="The macro for ISRs.">TASK_ISR</a>(TIMER1_COMPA_vect, tick_interrupt())<span class="comment">// Our entry point</span>int main(<span class="keywordtype">void</span>) { <span class="comment">// Interrupts should remain disabled - they will be enabled as soon as the first task starts executing</span> cli(); <span class="comment">// Set up port A for output</span> DDRA = 0xFF; <span class="comment">// Our idle task sleeps the CPU - set the sleep mode to IDLE, as we need the sleep to be</span> <span class="comment">// interruptable by the tick interrupt</span> set_sleep_mode(SLEEP_MODE_IDLE); <span class="comment">// Create our two tasks</span> <a class="code" href="group__task.html#g9b849c9a0e0b29417cf47da99226dcc3" title="Create a task, ready to be run.">create_task</a>(blink1, 0, 0, 55, 100, 0); <a class="code" href="group__task.html#g9b849c9a0e0b29417cf47da99226dcc3" title="Create a task, ready to be run.">create_task</a>(blink2, 0, 0, 55, 100, 0); <span class="comment">// Set up our TIMER1_COMPA interrupt to tick every 80,000 clock cycles</span> TCCR1B = 0x0A; OCR1A = 9999; TIFR = _BV(OCF1A); TIMSK |= _BV(OCIE1A); <span class="comment">// Start the RTOS - note that this function will never return</span> <a class="code" href="group__task.html#g1398c4d9f97349ea3fa7d91349298521" title="Start the whole process running.">task_switcher_start</a>(idle_task, 0, 55, 55); <span class="keywordflow">return</span> 0;}</pre></div> <hr><p align="center"><font size="-1">YAVRTOS and YAVRTOS documentation Copyright © 2007-2008 Chris O'Byrne. Email - chris <at> obyrne <dot> com</font></p></body></html>⌨️ 快捷键说明
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