http://www.ethernut.de/nutwiki/index.php?action=history&feed=atom&title=Timer_and_Counter_Interrupts 2026-04-22T23:51:39Z Revision history for this page on the wiki MediaWiki 1.26.2 http://www.ethernut.de/nutwiki/index.php?title=Timer_and_Counter_Interrupts&diff=280&oldid=prev 2016-10-27T16:03:02Z

<p>1 revision imported</p> <table class='diff diff-contentalign-left'> <tr style='vertical-align: top;' lang='en'> <td colspan='1' style="background-color: white; color:black; text-align: center;">← Older revision</td> <td colspan='1' style="background-color: white; color:black; text-align: center;">Revision as of 16:03, 27 October 2016</td> </tr><tr><td colspan='2' style='text-align: center;' lang='en'><div class="mw-diff-empty">(No difference)</div> </td></tr></table>

Harald http://www.ethernut.de/nutwiki/index.php?title=Timer_and_Counter_Interrupts&diff=279&oldid=prev 2009-09-11T12:50:55Z

<p>‎<span dir="auto"><span class="autocomment">AVR - How to Configure a Timer Compare Interrupt</span></span></p> <p><b>New page</b></p><div>== AVR - How to Configure a Timer Compare Interrupt ==<br /> <br /> Macros to define a time period, feel free to change 1ms to e.g. 4 etc.<br /> #define SAMPLE_PERIOD 1 //[ms]<br /> #define TIMER1_DIVISOR 14745600/(1000/SAMPLE_PERIOD) //NUT_CPU_FREQ/...<br /> <br /> This routine is periodically called.<br /> ''Note: In case IRQSTACK_SIZE is not defined, you run within an unpredictable context.''<br /> void '''Timer1Process'''(void *arg)<br /> {<br /> arg = arg; //requires gcc compiler (when called from thread)<br /> //NutRegisterIrqHandler callback fn has void* argument<br /> <br /> //your fn goes here<br /> }<br /> <br /> Following initialization (called only once) generates Timer1Process() interrupt calls every 1ms (0.999959 ms).<br /> <br /> 16 bit timer is used for accuracy. If timer2 (8bit) is used, you can reach 1,11111 ms (prescaler 128, OCR=128)<br /> <br /> void Timer1Init(void)<br /> {<br /> #ifdef MCU_ATMEGA_2561<br /> NutIrqDisable(&amp;sig_OUTPUT_COMPARE1A);<br /> #endif<br /> <br /> //COM1A, B, C = 0 (Compare Output Mode) = normal (output pin disconnected)<br /> //WGM = 4 (CTC - Clear Timer on Compare match)<br /> //CS = 1 (prescaler = 1)<br /> <br /> #ifdef MCU_ATMEGA_2561<br /> outb(TCCR1A, 0);<br /> #endif<br /> outb(TCCR1B, BV(WGM12) | BV(CS10)); //0x09<br /> #ifdef MCU_ATMEGA_2561<br /> cbi(TCCR1C, FOC1A);<br /> #endif<br /> //assume timer is disabled after power up<br /> //outb(TCNT1H, 0);<br /> //outb(TCNT1L, 0);<br /> <br /> //divisor<br /> outb(OCR1AH, TIMER1_DIVISOR &gt;&gt; 8); //0x39<br /> outb(OCR1AL, TIMER1_DIVISOR &amp; 0xFF); //0x99<br /> <br /> NutRegisterIrqHandler(&amp;sig_OUTPUT_COMPARE1A, '''Timer1Process''', 0);<br /> <br /> #ifdef MCU_ATMEGA_2561<br /> NutIrqEnable(&amp;sig_OUTPUT_COMPARE1A);<br /> #elif defined MCU_ATMEGA_128<br /> sbi(TIMSK, OCIE1A);<br /> #endif<br /> }<br /> <br /> == See also ==<br /> * More [[Nut/OS Examples]]</div>

AdrianPyka