timerx8_8c-source.html

单片机的软件

00156 {
00157     <span class="comment">//TODO: can we assume for all 3-timer AVR processors,</span>
00158     <span class="comment">// that timer2 is the RTC timer?</span>
00159 
00160     <span class="comment">// get the current prescaler setting</span>
00161     <span class="keywordflow">return</span> (pgm_read_word(TimerRTCPrescaleFactor+(TCCR2B &amp; <a class="code" href="group__timer.html#ga23">TIMER_PRESCALE_MASK</a>)));
00162 }
00163 <span class="preprocessor">#endif</span>
00164 <span class="preprocessor"></span>
<a name="l00165"></a><a class="code" href="group__timer.html#ga8">00165</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>) )
00166 {
00167     <span class="comment">// make sure the interrupt number is within bounds</span>
00168     <span class="keywordflow">if</span>(interruptNum &lt; TIMER_NUM_INTERRUPTS)
00169     {
00170         <span class="comment">// set the interrupt function to run</span>
00171         <span class="comment">// the supplied user's function</span>
00172         TimerIntFunc[interruptNum] = userFunc;
00173     }
00174 }
00175 
<a name="l00176"></a><a class="code" href="group__timer.html#ga9">00176</a> <span class="keywordtype">void</span> <a class="code" href="group__timer.html#ga9">timerDetach</a>(u08 interruptNum)
00177 {
00178     <span class="comment">// make sure the interrupt number is within bounds</span>
00179     <span class="keywordflow">if</span>(interruptNum &lt; TIMER_NUM_INTERRUPTS)
00180     {
00181         <span class="comment">// set the interrupt function to run nothing</span>
00182         TimerIntFunc[interruptNum] = 0;
00183     }
00184 }
00185 <span class="comment">/*</span>
00186 <span class="comment">u32 timerMsToTics(u16 ms)</span>
00187 <span class="comment">{</span>
00188 <span class="comment">    // calculate the prescaler division rate</span>
00189 <span class="comment">    u16 prescaleDiv = 1&lt;&lt;(pgm_read_byte(TimerPrescaleFactor+inb(TCCR0)));</span>
00190 <span class="comment">    // calculate the number of timer tics in x milliseconds</span>
00191 <span class="comment">    return (ms*(F_CPU/(prescaleDiv*256)))/1000;</span>
00192 <span class="comment">}</span>
00193 <span class="comment"></span>
00194 <span class="comment">u16 timerTicsToMs(u32 tics)</span>
00195 <span class="comment">{</span>
00196 <span class="comment">    // calculate the prescaler division rate</span>
00197 <span class="comment">    u16 prescaleDiv = 1&lt;&lt;(pgm_read_byte(TimerPrescaleFactor+inb(TCCR0)));</span>
00198 <span class="comment">    // calculate the number of milliseconds in x timer tics</span>
00199 <span class="comment">    return (tics*1000*(prescaleDiv*256))/F_CPU;</span>
00200 <span class="comment">}</span>
00201 <span class="comment">*/</span>
<a name="l00202"></a><a class="code" href="group__timer.html#ga10">00202</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)
00203 {
00204     <span class="comment">// pauses for exactly &lt;pause_ms&gt; number of milliseconds</span>
00205     u08 timerThres;
00206     u32 ticRateHz;
00207     u32 pause;
00208 
00209     <span class="comment">// capture current pause timer value</span>
00210     timerThres = TCNT0;
00211     <span class="comment">// reset pause timer overflow count</span>
00212     TimerPauseReg = 0;
00213     <span class="comment">// calculate delay for [pause_ms] milliseconds</span>
00214     <span class="comment">// prescaler division = 1&lt;&lt;(pgm_read_byte(TimerPrescaleFactor+inb(TCCR0)))</span>
00215     ticRateHz = F_CPU/<a class="code" href="group__timer.html#ga5">timer0GetPrescaler</a>();
00216     <span class="comment">// precision management</span>
00217     <span class="comment">// prevent overflow and precision underflow</span>
00218     <span class="comment">//  -could add more conditions to improve accuracy</span>
00219     <span class="keywordflow">if</span>( ((ticRateHz &lt; 429497) &amp;&amp; (pause_ms &lt;= 10000)) )
00220         pause = (pause_ms*ticRateHz)/1000;
00221     <span class="keywordflow">else</span>
00222         pause = pause_ms*(ticRateHz/1000);
00223 
00224     <span class="comment">// loop until time expires</span>
00225     <span class="keywordflow">while</span>( ((TimerPauseReg&lt;&lt;8) | (TCNT0)) &lt; (pause+timerThres) )
00226     {
00227         <span class="keywordflow">if</span>( TimerPauseReg &lt; (pause&gt;&gt;8));
00228         {
00229             <span class="comment">// save power by idling the processor</span>
00230             set_sleep_mode(SLEEP_MODE_IDLE);
00231             sleep_mode();
00232         }
00233     }
00234 
00235     <span class="comment">/* old inaccurate code, for reference</span>
00236 <span class="comment">    </span>
00237 <span class="comment">    // calculate delay for [pause_ms] milliseconds</span>
00238 <span class="comment">    u16 prescaleDiv = 1&lt;&lt;(pgm_read_byte(TimerPrescaleFactor+inb(TCCR0)));</span>
00239 <span class="comment">    u32 pause = (pause_ms*(F_CPU/(prescaleDiv*256)))/1000;</span>
00240 <span class="comment">    </span>
00241 <span class="comment">    TimerPauseReg = 0;</span>
00242 <span class="comment">    while(TimerPauseReg &lt; pause);</span>
00243 <span class="comment"></span>
00244 <span class="comment">    */</span>
00245 }
00246 
<a name="l00247"></a><a class="code" href="group__timer.html#ga11">00247</a> <span class="keywordtype">void</span> <a class="code" href="group__timer.html#ga11">timer0ClearOverflowCount</a>(<span class="keywordtype">void</span>)
00248 {
00249     <span class="comment">// clear the timer overflow counter registers</span>
00250     Timer0Reg0 = 0; <span class="comment">// initialize time registers</span>
00251 }
00252 
<a name="l00253"></a><a class="code" href="group__timer.html#ga12">00253</a> <span class="keywordtype">long</span> <a class="code" href="group__timer.html#ga12">timer0GetOverflowCount</a>(<span class="keywordtype">void</span>)
00254 {
00255     <span class="comment">// return the current timer overflow count</span>
00256     <span class="comment">// (this is since the last timer0ClearOverflowCount() command was called)</span>
00257     <span class="keywordflow">return</span> Timer0Reg0;
00258 }
00259 
00260 <span class="preprocessor">#ifdef TCNT2    // support timer2 only if it exists</span>
00261 <span class="preprocessor"></span><span class="keywordtype">void</span> timer2ClearOverflowCount(<span class="keywordtype">void</span>)
00262 {
00263     <span class="comment">// clear the timer overflow counter registers</span>
00264     Timer2Reg0 = 0; <span class="comment">// initialize time registers</span>
00265 }
00266 
00267 <span class="keywordtype">long</span> timer2GetOverflowCount(<span class="keywordtype">void</span>)
00268 {
00269     <span class="comment">// return the current timer overflow count</span>
00270     <span class="comment">// (this is since the last timer2ClearOverflowCount() command was called)</span>
00271     <span class="keywordflow">return</span> Timer2Reg0;
00272 }
00273 <span class="preprocessor">#endif</span>
00274 <span class="preprocessor"></span>
<a name="l00275"></a><a class="code" href="group__timerpwm.html#ga0">00275</a> <span class="keywordtype">void</span> <a class="code" href="group__timerpwm.html#ga0">timer1PWMInit</a>(u08 bitRes)
00276 {
00277     <span class="comment">// configures timer1 for use with PWM output</span>
00278     <span class="comment">// on OC1A and OC1B pins</span>
00279 
00280     <span class="comment">// enable timer1 as 8,9,10bit PWM</span>
00281     <span class="keywordflow">if</span>(bitRes == 9)
00282     {   <span class="comment">// 9bit mode</span>
00283         sbi(TCCR1A,PWM11);
00284         cbi(TCCR1A,PWM10);
00285     }
00286     <span class="keywordflow">else</span> <span class="keywordflow">if</span>( bitRes == 10 )
00287     {   <span class="comment">// 10bit mode</span>
00288         sbi(TCCR1A,PWM11);
00289         sbi(TCCR1A,PWM10);
00290     }
00291     <span class="keywordflow">else</span>
00292     {   <span class="comment">// default 8bit mode</span>
00293         cbi(TCCR1A,PWM11);
00294         sbi(TCCR1A,PWM10);
00295     }
00296 
00297     <span class="comment">// clear output compare value A</span>
00298     OCR1A = 0;
00299     <span class="comment">// clear output compare value B</span>
00300     OCR1B = 0;
00301 }
00302 
00303 <span class="preprocessor">#ifdef WGM10</span>
00304 <span class="preprocessor"></span><span class="comment">// include support for arbitrary top-count PWM</span>
00305 <span class="comment">// on new AVR processors that support it</span>
00306 <span class="keywordtype">void</span> <a class="code" href="group__timerpwm.html#ga1">timer1PWMInitICR</a>(u16 topcount)
00307 {
00308     <span class="comment">// set PWM mode with ICR top-count</span>
00309     cbi(TCCR1A,WGM10);
00310     sbi(TCCR1A,WGM11);
00311     sbi(TCCR1B,WGM12);
00312     sbi(TCCR1B,WGM13);
00313     
00314     <span class="comment">// set top count value</span>
00315     ICR1 = topcount;
00316     
00317     <span class="comment">// clear output compare value A</span>