timer_8c-source.html

avr应用测试程序

00155 
00156 <span class="preprocessor">#ifdef TCNT2    // support timer2 only if it exists</span>
00157 <span class="preprocessor"></span>u16 <a class="code" href="group__timer128.html#ga12">timer2GetPrescaler</a>(<span class="keywordtype">void</span>)
00158 {
00159     <span class="comment">//TODO: can we assume for all 3-timer AVR processors,</span>
00160     <span class="comment">// that timer2 is the RTC timer?</span>
00161 
00162     <span class="comment">// get the current prescaler setting</span>
00163     <span class="keywordflow">return</span> (pgm_read_word(TimerRTCPrescaleFactor+(inb(TCCR2) &amp; <a class="code" href="group__timer.html#ga23">TIMER_PRESCALE_MASK</a>)));
00164 }
00165 <span class="preprocessor">#endif</span>
00166 <span class="preprocessor"></span>
<a name="l00167"></a><a class="code" href="group__timerx8.html#ga8">00167</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>) )
00168 {
00169     <span class="comment">// make sure the interrupt number is within bounds</span>
00170     <span class="keywordflow">if</span>(interruptNum &lt; TIMER_NUM_INTERRUPTS)
00171     {
00172         <span class="comment">// set the interrupt function to run</span>
00173         <span class="comment">// the supplied user's function</span>
00174         TimerIntFunc[interruptNum] = userFunc;
00175     }
00176 }
00177 
<a name="l00178"></a><a class="code" href="group__timerx8.html#ga9">00178</a> <span class="keywordtype">void</span> <a class="code" href="group__timer.html#ga9">timerDetach</a>(u08 interruptNum)
00179 {
00180     <span class="comment">// make sure the interrupt number is within bounds</span>
00181     <span class="keywordflow">if</span>(interruptNum &lt; TIMER_NUM_INTERRUPTS)
00182     {
00183         <span class="comment">// set the interrupt function to run nothing</span>
00184         TimerIntFunc[interruptNum] = 0;
00185     }
00186 }
00187 <span class="comment">/*</span>
00188 <span class="comment">u32 timerMsToTics(u16 ms)</span>
00189 <span class="comment">{</span>
00190 <span class="comment">    // calculate the prescaler division rate</span>
00191 <span class="comment">    u16 prescaleDiv = 1&lt;&lt;(pgm_read_byte(TimerPrescaleFactor+inb(TCCR0)));</span>
00192 <span class="comment">    // calculate the number of timer tics in x milliseconds</span>
00193 <span class="comment">    return (ms*(F_CPU/(prescaleDiv*256)))/1000;</span>
00194 <span class="comment">}</span>
00195 <span class="comment"></span>
00196 <span class="comment">u16 timerTicsToMs(u32 tics)</span>
00197 <span class="comment">{</span>
00198 <span class="comment">    // calculate the prescaler division rate</span>
00199 <span class="comment">    u16 prescaleDiv = 1&lt;&lt;(pgm_read_byte(TimerPrescaleFactor+inb(TCCR0)));</span>
00200 <span class="comment">    // calculate the number of milliseconds in x timer tics</span>
00201 <span class="comment">    return (tics*1000*(prescaleDiv*256))/F_CPU;</span>
00202 <span class="comment">}</span>
00203 <span class="comment">*/</span>
<a name="l00204"></a><a class="code" href="group__timerx8.html#ga10">00204</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)
00205 {
00206     <span class="comment">// pauses for exactly &lt;pause_ms&gt; number of milliseconds</span>
00207     u08 timerThres;
00208     u32 ticRateHz;
00209     u32 pause;
00210 
00211     <span class="comment">// capture current pause timer value</span>
00212     timerThres = inb(TCNT0);
00213     <span class="comment">// reset pause timer overflow count</span>
00214     TimerPauseReg = 0;
00215     <span class="comment">// calculate delay for [pause_ms] milliseconds</span>
00216     <span class="comment">// prescaler division = 1&lt;&lt;(pgm_read_byte(TimerPrescaleFactor+inb(TCCR0)))</span>
00217     ticRateHz = F_CPU/<a class="code" href="group__timer.html#ga5">timer0GetPrescaler</a>();
00218     <span class="comment">// precision management</span>
00219     <span class="comment">// prevent overflow and precision underflow</span>
00220     <span class="comment">//  -could add more conditions to improve accuracy</span>
00221     <span class="keywordflow">if</span>( ((ticRateHz &lt; 429497) &amp;&amp; (pause_ms &lt;= 10000)) )
00222         pause = (pause_ms*ticRateHz)/1000;
00223     <span class="keywordflow">else</span>
00224         pause = pause_ms*(ticRateHz/1000);
00225 
00226     <span class="comment">// loop until time expires</span>
00227     <span class="keywordflow">while</span>( ((TimerPauseReg&lt;&lt;8) | inb(TCNT0)) &lt; (pause+timerThres) )
00228     {
00229         <span class="keywordflow">if</span>( TimerPauseReg &lt; (pause&gt;&gt;8));
00230         {
00231             <span class="comment">// save power by idling the processor</span>
00232             set_sleep_mode(SLEEP_MODE_IDLE);
00233             sleep_mode();
00234         }
00235     }
00236 
00237     <span class="comment">/* old inaccurate code, for reference</span>
00238 <span class="comment">    </span>
00239 <span class="comment">    // calculate delay for [pause_ms] milliseconds</span>
00240 <span class="comment">    u16 prescaleDiv = 1&lt;&lt;(pgm_read_byte(TimerPrescaleFactor+inb(TCCR0)));</span>
00241 <span class="comment">    u32 pause = (pause_ms*(F_CPU/(prescaleDiv*256)))/1000;</span>
00242 <span class="comment">    </span>
00243 <span class="comment">    TimerPauseReg = 0;</span>
00244 <span class="comment">    while(TimerPauseReg &lt; pause);</span>
00245 <span class="comment"></span>
00246 <span class="comment">    */</span>
00247 }
00248 
<a name="l00249"></a><a class="code" href="group__timerx8.html#ga11">00249</a> <span class="keywordtype">void</span> <a class="code" href="group__timer.html#ga11">timer0ClearOverflowCount</a>(<span class="keywordtype">void</span>)
00250 {
00251     <span class="comment">// clear the timer overflow counter registers</span>
00252     Timer0Reg0 = 0; <span class="comment">// initialize time registers</span>
00253 }
00254 
<a name="l00255"></a><a class="code" href="group__timerx8.html#ga12">00255</a> <span class="keywordtype">long</span> <a class="code" href="group__timer.html#ga12">timer0GetOverflowCount</a>(<span class="keywordtype">void</span>)
00256 {
00257     <span class="comment">// return the current timer overflow count</span>
00258     <span class="comment">// (this is since the last timer0ClearOverflowCount() command was called)</span>
00259     <span class="keywordflow">return</span> Timer0Reg0;
00260 }
00261 
00262 <span class="preprocessor">#ifdef TCNT2    // support timer2 only if it exists</span>
00263 <span class="preprocessor"></span><span class="keywordtype">void</span> timer2ClearOverflowCount(<span class="keywordtype">void</span>)
00264 {
00265     <span class="comment">// clear the timer overflow counter registers</span>
00266     Timer2Reg0 = 0; <span class="comment">// initialize time registers</span>
00267 }
00268 
00269 <span class="keywordtype">long</span> timer2GetOverflowCount(<span class="keywordtype">void</span>)
00270 {
00271     <span class="comment">// return the current timer overflow count</span>
00272     <span class="comment">// (this is since the last timer2ClearOverflowCount() command was called)</span>
00273     <span class="keywordflow">return</span> Timer2Reg0;
00274 }
00275 <span class="preprocessor">#endif</span>
00276 <span class="preprocessor"></span>
<a name="l00277"></a><a class="code" href="group__timerpwm.html#ga0">00277</a> <span class="keywordtype">void</span> <a class="code" href="group__timerpwm.html#ga0">timer1PWMInit</a>(u08 bitRes)
00278 {
00279     <span class="comment">// configures timer1 for use with PWM output</span>
00280     <span class="comment">// on OC1A and OC1B pins</span>
00281 
00282     <span class="comment">// enable timer1 as 8,9,10bit PWM</span>
00283     <span class="keywordflow">if</span>(bitRes == 9)
00284     {   <span class="comment">// 9bit mode</span>
00285         sbi(TCCR1A,PWM11);
00286         cbi(TCCR1A,PWM10);
00287     }
00288     <span class="keywordflow">else</span> <span class="keywordflow">if</span>( bitRes == 10 )
00289     {   <span class="comment">// 10bit mode</span>
00290         sbi(TCCR1A,PWM11);
00291         sbi(TCCR1A,PWM10);
00292     }
00293     <span class="keywordflow">else</span>
00294     {   <span class="comment">// default 8bit mode</span>
00295         cbi(TCCR1A,PWM11);
00296         sbi(TCCR1A,PWM10);
00297     }
00298 
00299     <span class="comment">// clear output compare value A</span>
00300     outb(OCR1AH, 0);
00301     outb(OCR1AL, 0);
00302     <span class="comment">// clear output compare value B</span>
00303     outb(OCR1BH, 0);
00304     outb(OCR1BL, 0);
00305 }
00306 
00307 <span class="preprocessor">#ifdef WGM10</span>
00308 <span class="preprocessor"></span><span class="comment">// include support for arbitrary top-count PWM</span>
00309 <span class="comment">// on new AVR processors that support it</span>
00310 <span class="keywordtype">void</span> <a class="code" href="group__timerpwm.html#ga1">timer1PWMInitICR</a>(u16 topcount)
00311 {
00312     <span class="comment">// set PWM mode with ICR top-count</span>
00313     cbi(TCCR1A,WGM10);
00314     sbi(TCCR1A,WGM11);
00315     sbi(TCCR1B,WGM12);