timerx8_8c-source.html

avr cpu 库源代码 对avr单片机编程很有帮助

00156     <span class="comment">//TODO: can we assume for all 3-timer AVR processors,</span>
00157     <span class="comment">// that timer2 is the RTC timer?</span>
00158 
00159     <span class="comment">// get the current prescaler setting</span>
00160     <span class="keywordflow">return</span> (pgm_read_word(TimerRTCPrescaleFactor+(TCCR2B &amp; <a class="code" href="group__timer.html#ga23">TIMER_PRESCALE_MASK</a>)));
00161 }
00162 <span class="preprocessor">#endif</span>
00163 <span class="preprocessor"></span>
<a name="l00164"></a><a class="code" href="group__timer.html#ga8">00164</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>) )
00165 {
00166     <span class="comment">// make sure the interrupt number is within bounds</span>
00167     <span class="keywordflow">if</span>(interruptNum &lt; TIMER_NUM_INTERRUPTS)
00168     {
00169         <span class="comment">// set the interrupt function to run</span>
00170         <span class="comment">// the supplied user's function</span>
00171         TimerIntFunc[interruptNum] = userFunc;
00172     }
00173 }
00174 
<a name="l00175"></a><a class="code" href="group__timer.html#ga9">00175</a> <span class="keywordtype">void</span> <a class="code" href="group__timer.html#ga9">timerDetach</a>(u08 interruptNum)
00176 {
00177     <span class="comment">// make sure the interrupt number is within bounds</span>
00178     <span class="keywordflow">if</span>(interruptNum &lt; TIMER_NUM_INTERRUPTS)
00179     {
00180         <span class="comment">// set the interrupt function to run nothing</span>
00181         TimerIntFunc[interruptNum] = 0;
00182     }
00183 }
00184 <span class="comment">/*</span>
00185 <span class="comment">u32 timerMsToTics(u16 ms)</span>
00186 <span class="comment">{</span>
00187 <span class="comment">    // calculate the prescaler division rate</span>
00188 <span class="comment">    u16 prescaleDiv = 1&lt;&lt;(pgm_read_byte(TimerPrescaleFactor+inb(TCCR0)));</span>
00189 <span class="comment">    // calculate the number of timer tics in x milliseconds</span>
00190 <span class="comment">    return (ms*(F_CPU/(prescaleDiv*256)))/1000;</span>
00191 <span class="comment">}</span>
00192 <span class="comment"></span>
00193 <span class="comment">u16 timerTicsToMs(u32 tics)</span>
00194 <span class="comment">{</span>
00195 <span class="comment">    // calculate the prescaler division rate</span>
00196 <span class="comment">    u16 prescaleDiv = 1&lt;&lt;(pgm_read_byte(TimerPrescaleFactor+inb(TCCR0)));</span>
00197 <span class="comment">    // calculate the number of milliseconds in x timer tics</span>
00198 <span class="comment">    return (tics*1000*(prescaleDiv*256))/F_CPU;</span>
00199 <span class="comment">}</span>
00200 <span class="comment">*/</span>
<a name="l00201"></a><a class="code" href="group__timer.html#ga10">00201</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)
00202 {
00203     <span class="comment">// pauses for exactly &lt;pause_ms&gt; number of milliseconds</span>
00204     u08 timerThres;
00205     u32 ticRateHz;
00206     u32 pause;
00207 
00208     <span class="comment">// capture current pause timer value</span>
00209     timerThres = TCNT0;
00210     <span class="comment">// reset pause timer overflow count</span>
00211     TimerPauseReg = 0;
00212     <span class="comment">// calculate delay for [pause_ms] milliseconds</span>
00213     <span class="comment">// prescaler division = 1&lt;&lt;(pgm_read_byte(TimerPrescaleFactor+inb(TCCR0)))</span>
00214     ticRateHz = F_CPU/<a class="code" href="group__timer.html#ga5">timer0GetPrescaler</a>();
00215     <span class="comment">// precision management</span>
00216     <span class="comment">// prevent overflow and precision underflow</span>
00217     <span class="comment">//  -could add more conditions to improve accuracy</span>
00218     <span class="keywordflow">if</span>( ((ticRateHz &lt; 429497) &amp;&amp; (pause_ms &lt;= 10000)) )
00219         pause = (pause_ms*ticRateHz)/1000;
00220     <span class="keywordflow">else</span>
00221         pause = pause_ms*(ticRateHz/1000);
00222 
00223     <span class="comment">// loop until time expires</span>
00224     <span class="keywordflow">while</span>( ((TimerPauseReg&lt;&lt;8) | (TCNT0)) &lt; (pause+timerThres) )
00225     {
00226         <span class="keywordflow">if</span>( TimerPauseReg &lt; (pause&gt;&gt;8));
00227         {
00228             <span class="comment">// save power by idling the processor</span>
00229             set_sleep_mode(SLEEP_MODE_IDLE);
00230             sleep_mode();
00231         }
00232     }
00233 
00234     <span class="comment">/* old inaccurate code, for reference</span>
00235 <span class="comment">    </span>
00236 <span class="comment">    // calculate delay for [pause_ms] milliseconds</span>
00237 <span class="comment">    u16 prescaleDiv = 1&lt;&lt;(pgm_read_byte(TimerPrescaleFactor+inb(TCCR0)));</span>
00238 <span class="comment">    u32 pause = (pause_ms*(F_CPU/(prescaleDiv*256)))/1000;</span>
00239 <span class="comment">    </span>
00240 <span class="comment">    TimerPauseReg = 0;</span>
00241 <span class="comment">    while(TimerPauseReg &lt; pause);</span>
00242 <span class="comment"></span>
00243 <span class="comment">    */</span>
00244 }
00245 
<a name="l00246"></a><a class="code" href="group__timer.html#ga11">00246</a> <span class="keywordtype">void</span> <a class="code" href="group__timer.html#ga11">timer0ClearOverflowCount</a>(<span class="keywordtype">void</span>)
00247 {
00248     <span class="comment">// clear the timer overflow counter registers</span>
00249     Timer0Reg0 = 0; <span class="comment">// initialize time registers</span>
00250 }
00251 
<a name="l00252"></a><a class="code" href="group__timer.html#ga12">00252</a> <span class="keywordtype">long</span> <a class="code" href="group__timer.html#ga12">timer0GetOverflowCount</a>(<span class="keywordtype">void</span>)
00253 {
00254     <span class="comment">// return the current timer overflow count</span>
00255     <span class="comment">// (this is since the last timer0ClearOverflowCount() command was called)</span>
00256     <span class="keywordflow">return</span> Timer0Reg0;
00257 }
00258 
00259 <span class="preprocessor">#ifdef TCNT2    // support timer2 only if it exists</span>
00260 <span class="preprocessor"></span><span class="keywordtype">void</span> timer2ClearOverflowCount(<span class="keywordtype">void</span>)
00261 {
00262     <span class="comment">// clear the timer overflow counter registers</span>
00263     Timer2Reg0 = 0; <span class="comment">// initialize time registers</span>
00264 }
00265 
00266 <span class="keywordtype">long</span> timer2GetOverflowCount(<span class="keywordtype">void</span>)
00267 {
00268     <span class="comment">// return the current timer overflow count</span>
00269     <span class="comment">// (this is since the last timer2ClearOverflowCount() command was called)</span>
00270     <span class="keywordflow">return</span> Timer2Reg0;
00271 }
00272 <span class="preprocessor">#endif</span>
00273 <span class="preprocessor"></span>
<a name="l00274"></a><a class="code" href="group__timerpwm.html#ga0">00274</a> <span class="keywordtype">void</span> <a class="code" href="group__timerpwm.html#ga0">timer1PWMInit</a>(u08 bitRes)
00275 {
00276     <span class="comment">// configures timer1 for use with PWM output</span>
00277     <span class="comment">// on OC1A and OC1B pins</span>
00278 
00279     <span class="comment">// enable timer1 as 8,9,10bit PWM</span>
00280     <span class="keywordflow">if</span>(bitRes == 9)
00281     {   <span class="comment">// 9bit mode</span>
00282         sbi(TCCR1A,PWM11);
00283         cbi(TCCR1A,PWM10);
00284     }
00285     <span class="keywordflow">else</span> <span class="keywordflow">if</span>( bitRes == 10 )
00286     {   <span class="comment">// 10bit mode</span>
00287         sbi(TCCR1A,PWM11);
00288         sbi(TCCR1A,PWM10);
00289     }
00290     <span class="keywordflow">else</span>
00291     {   <span class="comment">// default 8bit mode</span>
00292         cbi(TCCR1A,PWM11);
00293         sbi(TCCR1A,PWM10);
00294     }
00295 
00296     <span class="comment">// clear output compare value A</span>
00297     OCR1A = 0;
00298     <span class="comment">// clear output compare value B</span>
00299     OCR1B = 0;
00300 }
00301 
00302 <span class="preprocessor">#ifdef WGM10</span>
00303 <span class="preprocessor"></span><span class="comment">// include support for arbitrary top-count PWM</span>
00304 <span class="comment">// on new AVR processors that support it</span>
00305 <span class="keywordtype">void</span> <a class="code" href="group__timerpwm.html#ga1">timer1PWMInitICR</a>(u16 topcount)
00306 {
00307     <span class="comment">// set PWM mode with ICR top-count</span>
00308     cbi(TCCR1A,WGM10);
00309     sbi(TCCR1A,WGM11);
00310     sbi(TCCR1B,WGM12);
00311     sbi(TCCR1B,WGM13);
00312     
00313     <span class="comment">// set top count value</span>
00314     ICR1 = topcount;
00315     
00316     <span class="comment">// clear output compare value A</span>
00317     OCR1A = 0;