timer_8c-source.html

国外牛人公开的ＡＶＲ代码

00156     <span class="keywordflow">return</span> (pgm_read_word(TimerPrescaleFactor+(inb(TCCR1B) &amp; <a class="code" href="group__timer.html#ga23">TIMER_PRESCALE_MASK</a>)));
00157 }
00158 
00159 <span class="preprocessor">#ifdef TCNT2    // support timer2 only if it exists</span>
00160 <span class="preprocessor"></span>u16 <a class="code" href="group__timer128.html#ga12">timer2GetPrescaler</a>(<span class="keywordtype">void</span>)
00161 {
00162     <span class="comment">//TODO: can we assume for all 3-timer AVR processors,</span>
00163     <span class="comment">// that timer2 is the RTC timer?</span>
00164 
00165     <span class="comment">// get the current prescaler setting</span>
00166     <span class="keywordflow">return</span> (pgm_read_word(TimerRTCPrescaleFactor+(inb(TCCR2) &amp; <a class="code" href="group__timer.html#ga23">TIMER_PRESCALE_MASK</a>)));
00167 }
00168 <span class="preprocessor">#endif</span>
00169 <span class="preprocessor"></span>
<a name="l00170"></a><a class="code" href="group__timerx8.html#ga8">00170</a> <span class="keywordtype">void</span> <a class="code" href="group__timer.html#ga8">timerAttach</a>(u08 interruptNum, <span class="keywordtype">void</span> (*userFunc)(<span class="keywordtype">void</span>) )
00171 {
00172     <span class="comment">// make sure the interrupt number is within bounds</span>
00173     <span class="keywordflow">if</span>(interruptNum &lt; TIMER_NUM_INTERRUPTS)
00174     {
00175         <span class="comment">// set the interrupt function to run</span>
00176         <span class="comment">// the supplied user's function</span>
00177         TimerIntFunc[interruptNum] = userFunc;
00178     }
00179 }
00180 
<a name="l00181"></a><a class="code" href="group__timerx8.html#ga9">00181</a> <span class="keywordtype">void</span> <a class="code" href="group__timer.html#ga9">timerDetach</a>(u08 interruptNum)
00182 {
00183     <span class="comment">// make sure the interrupt number is within bounds</span>
00184     <span class="keywordflow">if</span>(interruptNum &lt; TIMER_NUM_INTERRUPTS)
00185     {
00186         <span class="comment">// set the interrupt function to run nothing</span>
00187         TimerIntFunc[interruptNum] = 0;
00188     }
00189 }
00190 <span class="comment">/*</span>
00191 <span class="comment">u32 timerMsToTics(u16 ms)</span>
00192 <span class="comment">{</span>
00193 <span class="comment">    // calculate the prescaler division rate</span>
00194 <span class="comment">    u16 prescaleDiv = 1&lt;&lt;(pgm_read_byte(TimerPrescaleFactor+inb(TCCR0)));</span>
00195 <span class="comment">    // calculate the number of timer tics in x milliseconds</span>
00196 <span class="comment">    return (ms*(F_CPU/(prescaleDiv*256)))/1000;</span>
00197 <span class="comment">}</span>
00198 <span class="comment"></span>
00199 <span class="comment">u16 timerTicsToMs(u32 tics)</span>
00200 <span class="comment">{</span>
00201 <span class="comment">    // calculate the prescaler division rate</span>
00202 <span class="comment">    u16 prescaleDiv = 1&lt;&lt;(pgm_read_byte(TimerPrescaleFactor+inb(TCCR0)));</span>
00203 <span class="comment">    // calculate the number of milliseconds in x timer tics</span>
00204 <span class="comment">    return (tics*1000*(prescaleDiv*256))/F_CPU;</span>
00205 <span class="comment">}</span>
00206 <span class="comment">*/</span>
<a name="l00207"></a><a class="code" href="group__timerx8.html#ga10">00207</a> <span class="keywordtype">void</span> <a class="code" href="group__timer.html#ga10">timerPause</a>(<span class="keywordtype">unsigned</span> <span class="keywordtype">short</span> pause_ms)
00208 {
00209     <span class="comment">// pauses for exactly &lt;pause_ms&gt; number of milliseconds</span>
00210     u08 timerThres;
00211     u32 ticRateHz;
00212     u32 pause;
00213 
00214     <span class="comment">// capture current pause timer value</span>
00215     timerThres = inb(TCNT0);
00216     <span class="comment">// reset pause timer overflow count</span>
00217     TimerPauseReg = 0;
00218     <span class="comment">// calculate delay for [pause_ms] milliseconds</span>
00219     <span class="comment">// prescaler division = 1&lt;&lt;(pgm_read_byte(TimerPrescaleFactor+inb(TCCR0)))</span>
00220     ticRateHz = F_CPU/<a class="code" href="group__timer.html#ga5">timer0GetPrescaler</a>();
00221     <span class="comment">// precision management</span>
00222     <span class="comment">// prevent overflow and precision underflow</span>
00223     <span class="comment">//  -could add more conditions to improve accuracy</span>
00224     <span class="keywordflow">if</span>( ((ticRateHz &lt; 429497) &amp;&amp; (pause_ms &lt;= 10000)) )
00225         pause = (pause_ms*ticRateHz)/1000;
00226     <span class="keywordflow">else</span>
00227         pause = pause_ms*(ticRateHz/1000);
00228 
00229     <span class="comment">// loop until time expires</span>
00230     <span class="keywordflow">while</span>( ((TimerPauseReg&lt;&lt;8) | inb(TCNT0)) &lt; (pause+timerThres) )
00231     {
00232         <span class="keywordflow">if</span>( TimerPauseReg &lt; (pause&gt;&gt;8));
00233         {
00234             <span class="comment">// save power by idling the processor</span>
00235             set_sleep_mode(SLEEP_MODE_IDLE);
00236             sleep_mode();
00237         }
00238     }
00239 
00240     <span class="comment">/* old inaccurate code, for reference</span>
00241 <span class="comment">    </span>
00242 <span class="comment">    // calculate delay for [pause_ms] milliseconds</span>
00243 <span class="comment">    u16 prescaleDiv = 1&lt;&lt;(pgm_read_byte(TimerPrescaleFactor+inb(TCCR0)));</span>
00244 <span class="comment">    u32 pause = (pause_ms*(F_CPU/(prescaleDiv*256)))/1000;</span>
00245 <span class="comment">    </span>
00246 <span class="comment">    TimerPauseReg = 0;</span>
00247 <span class="comment">    while(TimerPauseReg &lt; pause);</span>
00248 <span class="comment"></span>
00249 <span class="comment">    */</span>
00250 }
00251 
<a name="l00252"></a><a class="code" href="group__timerx8.html#ga11">00252</a> <span class="keywordtype">void</span> <a class="code" href="group__timer.html#ga11">timer0ClearOverflowCount</a>(<span class="keywordtype">void</span>)
00253 {
00254     <span class="comment">// clear the timer overflow counter registers</span>
00255     Timer0Reg0 = 0; <span class="comment">// initialize time registers</span>
00256 }
00257 
<a name="l00258"></a><a class="code" href="group__timerx8.html#ga12">00258</a> <span class="keywordtype">long</span> <a class="code" href="group__timer.html#ga12">timer0GetOverflowCount</a>(<span class="keywordtype">void</span>)
00259 {
00260     <span class="comment">// return the current timer overflow count</span>
00261     <span class="comment">// (this is since the last timer0ClearOverflowCount() command was called)</span>
00262     <span class="keywordflow">return</span> Timer0Reg0;
00263 }
00264 
00265 <span class="preprocessor">#ifdef TCNT2    // support timer2 only if it exists</span>
00266 <span class="preprocessor"></span><span class="keywordtype">void</span> timer2ClearOverflowCount(<span class="keywordtype">void</span>)
00267 {
00268     <span class="comment">// clear the timer overflow counter registers</span>
00269     Timer2Reg0 = 0; <span class="comment">// initialize time registers</span>
00270 }
00271 
00272 <span class="keywordtype">long</span> timer2GetOverflowCount(<span class="keywordtype">void</span>)
00273 {
00274     <span class="comment">// return the current timer overflow count</span>
00275     <span class="comment">// (this is since the last timer2ClearOverflowCount() command was called)</span>
00276     <span class="keywordflow">return</span> Timer2Reg0;
00277 }
00278 <span class="preprocessor">#endif</span>
00279 <span class="preprocessor"></span>
<a name="l00280"></a><a class="code" href="group__timerpwm.html#ga0">00280</a> <span class="keywordtype">void</span> <a class="code" href="group__timerpwm.html#ga0">timer1PWMInit</a>(u08 bitRes)
00281 {
00282     <span class="comment">// configures timer1 for use with PWM output</span>
00283     <span class="comment">// on OC1A and OC1B pins</span>
00284 
00285     <span class="comment">// enable timer1 as 8,9,10bit PWM</span>
00286     <span class="keywordflow">if</span>(bitRes == 9)
00287     {   <span class="comment">// 9bit mode</span>
00288         sbi(TCCR1A,PWM11);
00289         cbi(TCCR1A,PWM10);
00290     }
00291     <span class="keywordflow">else</span> <span class="keywordflow">if</span>( bitRes == 10 )
00292     {   <span class="comment">// 10bit mode</span>
00293         sbi(TCCR1A,PWM11);
00294         sbi(TCCR1A,PWM10);
00295     }
00296     <span class="keywordflow">else</span>
00297     {   <span class="comment">// default 8bit mode</span>
00298         cbi(TCCR1A,PWM11);
00299         sbi(TCCR1A,PWM10);
00300     }
00301 
00302     <span class="comment">// clear output compare value A</span>
00303     outb(OCR1AH, 0);
00304     outb(OCR1AL, 0);
00305     <span class="comment">// clear output compare value B</span>
00306     outb(OCR1BH, 0);
00307     outb(OCR1BL, 0);
00308 }
00309 
00310 <span class="preprocessor">#ifdef WGM10</span>
00311 <span class="preprocessor"></span><span class="comment">// include support for arbitrary top-count PWM</span>
00312 <span class="comment">// on new AVR processors that support it</span>
00313 <span class="keywordtype">void</span> <a class="code" href="group__timerpwm.html#ga1">timer1PWMInitICR</a>(u16 topcount)
00314 {
00315     <span class="comment">// set PWM mode with ICR top-count</span>
00316     cbi(TCCR1A,WGM10);
00317     sbi(TCCR1A,WGM11);