Timer logic on AVR -

-

i trying understand piece of code, not able understand how interrupt routine works ocr1a getting updated. using avr series of controller run code.

 void timerinit(void)     {         disable_timer_int;  // disable timer interrupt          m_nglobaltime = 0;  // reset system time          ocr1a  += ticks_per_msecond;    // set first clock period          tccr1a  = 0;// set timermode normal         tccr1b |= (1 << cs10);// clckio, no pre-scaler; set timermode          enable_interrupts;         enable_timer_int;// enable send timer interrupt (1 ms)     }        isr( timer1_compa_vect) {         uint16_t ntemp;           ntemp = tcnt1;  // current time         ntemp -= ocr1a; // subtract interrupt time          if (ntemp < (ticks_per_msecond / 2))// if more half period left             {             ocr1a += (ticks_per_msecond);// add offset ocr1a relative         }          else         {             ocr1a = tcnt1 + (ticks_per_msecond);// set ocr1a 1 ms absolute         }          m_nglobaltime++;                                                                 }

the usual way output compare interrupt fire @ regular interval add constant amount ocr1a. happening at

ocr1a += (ticks_per_msecond);

for reason, writer added logic handle bad luck. perhaps, period short, or maybe oc interrupt may delayed due other interrupt running.

if these cases occur, next oc interrupt not occur ticks_per_msecond later last, rather ticks_per_msecond plus entire cycle of counter. is, correct time missed, oc register set number after number has been passed.

this code attempt correct situation. being said, i'm not sure works correctly. potential problem ntemp unsigned, < comparison might not writer expects.


Comments

Post a Comment

Popular posts from this blog

yii2 - Yii 2 Running a Cron in the basic template -

-
i have seen instructions on running cron in advanced template, cant figure out how on basic template. have following controller in basic controllers folder. <?php namespace app\controllers; use yii\console\controller; /** * cron controller */ class croncontroller extends controller { public function actionindex() { echo "cron service runnning"; } public function actionmail($to) { echo "sending mail " . $to; } } i have navigated root of application , tried these comands yii cron php yii cron im getting unknown comand "cron" i know old question failed find actual answer this. if @ code yii exec file you'll notice requires /common/config/aliases.php file console/config/main.php. can naturally change these or copy on these advanced template. hope solves problem wanting same thing.
Read more

asp.net - 'System.Web.HttpContext' does not contain a definition for 'GetOwinContext' Mystery -

-
i realize question might seem trivial some, it's these types of things find myself fighting quite bit , want make sense of despite seeming losing battle in .net (for me anyway). so, if following: using system.web; ... applicationuser user = system.web.httpcontext.getowincontext().getusermanager<applicationusermanager>().findbyid(system.web.httpcontext.user.identity.getuserid()); that produces error in title , red getowincontext() , error cannot resolve symbol 'getowincontext()' however, if following (remove system.web in front of httpcontext ), works expected (or @ least no errors): using system.web; ... applicationuser user = httpcontext.getowincontext().getusermanager<applicationusermanager>().findbyid(system.web.httpcontext.user.identity.getuserid()); however, if (same line that's working using system.web commented out): //using system.web; ... applicationuser user = httpcontext.getowincontext().getusermana...
Read more

mercurial graft feature, can it copy? -

-
there new feature in mercurial 3, called 'graft' (graft local). job of moving change-set different branch. is there way "copy" change-set branch? i interested in in moving stuff qa branch production branch, still need code reside in qa. want copy. found , have tried few things, maybe it'll become clear more tinkering , reading... does have better way of 'cherry picking' change-sets move cross branch (or trunk)??? graft copies changesets, doesn't move them. hg graft (emphasis mine): this command uses mercurial's merge logic copy individual changes other branches without merging branches in history graph. known 'backporting' or 'cherry-picking' . default, graft copy user, date, , description source changesets.
Read more