pulse_8c-source.html

ATMEL的AVR单片机库文件

00141     <span class="comment">// enable OutputCompare interrupt</span>
00142     sbi(TIMSK, OCIE1A);
00143 }
00144 
00145 <span class="keywordtype">void</span> pulseT1BRun(u16 nPulses)
00146 {
00147     <span class="comment">// set the number of pulses we want and the mode</span>
00148     <span class="keywordflow">if</span>(nPulses)
00149     {
00150         <span class="comment">// if the nPulses is non-zero, use "counted" mode</span>
00151         PulseT1BMode |= PULSE_MODE_COUNTED;
00152         PulseT1BCount = nPulses&lt;&lt;1;
00153     }
00154     <span class="keywordflow">else</span>
00155     {
00156         <span class="comment">// if nPulses is zero, run forever</span>
00157         PulseT1BMode &amp;= ~PULSE_MODE_COUNTED;
00158         PulseT1BCount = 1&lt;&lt;1;
00159     }
00160     <span class="comment">// set OutputCompare action to toggle OC1B pin</span>
00161     <span class="comment">// (note: with all the A's and B's flying around, TCCR1A is not a bug)</span>
00162     cbi(TCCR1A,COM1B1);
00163     sbi(TCCR1A,COM1B0);
00164 
00165     <span class="comment">// now the "enabling" stuff</span>
00166 
00167     <span class="comment">// set the output compare one pulse cycle ahead of current timer position </span>
00168     <span class="comment">// to make sure we don't have to wait until the timer overflows and comes</span>
00169     <span class="comment">// back to the current value</span>
00170     <span class="comment">// set future output compare time to TCNT1 + PulseT1APeriodTics</span>
00171     outw(OCR1B, inw(TCNT1) + PulseT1BPeriodTics);
00172 
00173     <span class="comment">// enable OutputCompare interrupt</span>
00174     sbi(TIMSK, OCIE1B);
00175 }
00176 
00177 <span class="keywordtype">void</span> pulseT1AStop(<span class="keywordtype">void</span>)
00178 {
00179     <span class="comment">// stop output regardless of remaining pulses or mode</span>
00180     <span class="comment">// go to "counted" mode</span>
00181     PulseT1AMode |= PULSE_MODE_COUNTED;
00182     <span class="comment">// set pulses to zero</span>
00183     PulseT1ACount = 0;
00184 }
00185 
00186 <span class="keywordtype">void</span> pulseT1BStop(<span class="keywordtype">void</span>)
00187 {
00188     <span class="comment">// stop output regardless of remaining pulses or mode</span>
00189     <span class="comment">// go to "counted" mode</span>
00190     PulseT1BMode |= PULSE_MODE_COUNTED;
00191     <span class="comment">// set pulses to zero</span>
00192     PulseT1BCount = 0;
00193 }
00194 
00195 u16 pulseT1ARemaining(<span class="keywordtype">void</span>)
00196 {
00197     <span class="comment">// return the number of pulses remaining for channel A</span>
00198     <span class="comment">// add 1 to make sure we round up, &gt;&gt;1 equivalent to /2</span>
00199     <span class="keywordflow">return</span> (PulseT1ACount+1)&gt;&gt;1;
00200 }
00201 
00202 u16 pulseT1BRemaining(<span class="keywordtype">void</span>)
00203 {
00204     <span class="comment">// return the number of pulses remaining for channel A</span>
00205     <span class="comment">// add 1 to make sure we round up, &gt;&gt;1 equivalent to /2</span>
00206     <span class="keywordflow">return</span> (PulseT1BCount+1)&gt;&gt;1;
00207 }
00208 
00209 <span class="keywordtype">void</span> pulseT1AService(<span class="keywordtype">void</span>)
00210 {
00211     <span class="comment">// check if TimerPulseACount is non-zero</span>
00212     <span class="comment">//      (i.e. pulses are still requested)</span>
00213     <span class="keywordflow">if</span>(PulseT1ACount)
00214     {
00215         <span class="comment">//u16 OCValue;</span>
00216         <span class="comment">// read in current value of output compare register OCR1A</span>
00217         <span class="comment">//OCValue =  inp(OCR1AL);       // read low byte of OCR1A</span>
00218         <span class="comment">//OCValue += inp(OCR1AH)&lt;&lt;8;    // read high byte of OCR1A</span>
00219         <span class="comment">// increment OCR1A value by PulseT1APeriodTics</span>
00220         <span class="comment">//OCValue += PulseT1APeriodTics;</span>
00221         <span class="comment">// set future output compare time to this new value</span>
00222         <span class="comment">//outp((OCValue&gt;&gt;8),        OCR1AH);    // write high byte</span>
00223         <span class="comment">//outp((OCValue &amp; 0x00FF),OCR1AL);  // write low byte</span>
00224 
00225         <span class="comment">// the following line should be identical in operation</span>
00226         <span class="comment">// to the lines above, but for the moment, I'm not convinced</span>
00227         <span class="comment">// this method is bug-free.  At least it's simpler!</span>
00228         outw(OCR1A, inw(OCR1A) + PulseT1APeriodTics);
00229                 
00230         <span class="comment">// decrement the number of pulses executed</span>
00231         <span class="keywordflow">if</span>(PulseT1AMode &amp; PULSE_MODE_COUNTED)
00232             PulseT1ACount--;
00233     }
00234     <span class="keywordflow">else</span>
00235     {
00236         <span class="comment">// pulse count has reached zero</span>
00237         <span class="comment">// disable the output compare's action on OC1A pin</span>
00238         cbi(TCCR1A,COM1A1);
00239         cbi(TCCR1A,COM1A0);
00240         <span class="comment">// and disable the output compare's interrupt to stop pulsing</span>
00241         cbi(TIMSK, OCIE1A);
00242     }
00243 }
00244 
00245 <span class="keywordtype">void</span> pulseT1BService(<span class="keywordtype">void</span>)
00246 {
00247     <span class="comment">// check if TimerPulseACount is non-zero</span>
00248     <span class="comment">//      (i.e. pulses are still requested)</span>
00249     <span class="keywordflow">if</span>(PulseT1BCount)
00250     {
00251         <span class="comment">//u16 OCValue;</span>
00252         <span class="comment">// read in current value of output compare register OCR1B</span>
00253         <span class="comment">//OCValue =  inp(OCR1BL);       // read low byte of OCR1B</span>
00254         <span class="comment">//OCValue += inp(OCR1BH)&lt;&lt;8;    // read high byte of OCR1B</span>
00255         <span class="comment">// increment OCR1B value by PulseT1BPeriodTics</span>
00256         <span class="comment">//OCValue += PulseT1BPeriodTics; </span>
00257         <span class="comment">// set future output compare time to this new value</span>
00258         <span class="comment">//outp((OCValue&gt;&gt;8),        OCR1BH);    // write high byte</span>
00259         <span class="comment">//outp((OCValue &amp; 0x00FF),OCR1BL);  // write low byte</span>
00260 
00261         <span class="comment">// the following line should be identical in operation</span>
00262         <span class="comment">// to the lines above, but for the moment, I'm not convinced</span>
00263         <span class="comment">// this method is bug-free.  At least it's simpler!</span>
00264         outw(OCR1B, inw(OCR1B) + PulseT1BPeriodTics);
00265         
00266         <span class="comment">// decrement the number of pulses executed</span>
00267         <span class="keywordflow">if</span>(PulseT1BMode &amp; PULSE_MODE_COUNTED)
00268             PulseT1BCount--;
00269     }
00270     <span class="keywordflow">else</span>
00271     {
00272         <span class="comment">// pulse count has reached zero</span>
00273         <span class="comment">// disable the output compare's action on OC1B pin</span>
00274         cbi(TCCR1A,COM1B1);
00275         cbi(TCCR1A,COM1B0);
00276         <span class="comment">// and disable the output compare's interrupt to stop pulsing</span>
00277         cbi(TIMSK, OCIE1B);
00278     }
00279 }
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