![]() ![]() (subject to the options specified for the timer) while the timer Immediately after the transaction commits (subject to the options If the start time is in the past, the initial timer event is fired Timer events are delivered on the specified Activity Periodic timer may have either a finite or infinite number of Reached, a timer event is generated and the timer continues, generatingįurther timer events at the rate specified by the timer's period. When the start time of a periodic timer has been setTimer TimerID setTimer( Activit圜ontextInterface aci,.FacilityException - if the timer could not be set due to a TransactionRolledbackLocalException - if this method was invoked withoutĪ valid transaction context and the transaction started by this methodįailed to commit. IllegalArgumentException - if expireTime is less Returns: the timer ID of the timer that was set. options - the desired behavior of the timer. expireTime - the time (in ms since JanuUTC) that the address - the optional default address on which the timer event Parameters: aci - the Activity Context on which the timer event should beįired. This method is a required transactional method. If the expiry time is in the past, the timer event is fired immediatelyĪfter the transaction commits (subject to the options specified for the Is delivered on the specified Activity Context. Timer expires, after which the timer ceases to exist. A single timer event is generated when the Timers that take into account the timer resolution of the Timer Facility. The approximate timer resolution of the Timer FacilityĬan be obtained via getResolution(), allowing SBB entities to create Milliseconds, a Timer Facility implementation may be limited by theĪvailable clock resolution and/or scheduler implementation of the The Timer Facility is bound into JNDI using the name specifiedĪlthough the unit for the period of a periodic timer is specified in Which case the Timer Facility can consider it never set.Īn SBB obtains access to a TimerFacility object via its JNDIĮnvironment. A timer may be set and cancelled in the same transaction, in If the transaction in which their setup or cancellation took place commits This facility is transactional in nature. This TimerID to the cancelTimer() method. The timer can be cancelled at a later time by passing Timer is set, the Timer Facility generates a TimerID that TimersĪre identified by a serializable TimerID object. My interest in this is purely academic, with a potential end goal of attempting to measure the speed of light.The Timer Facility allows an SBB entity to set and cancel timers. I used this code to flash an LED, and determined that I had a resolution of around 500ns an order of magnitude worse than my target! Is my code incorrect? Is it just less efficient than it could be? Or am I flogging a dead horse am I ever going to get down to 62.5ns? Setting the prescaler to 1 and the value in the register to 255 (leaving only one incrementation until overflow) theoretically makes the register overflow every 62.5ns. For the most part, I only know approximately what the code does: The arduino's timer2 increments the value in an 8 bit register, when this overflows an interrupt is fired. I guessed that TCCR2B = 0x1 makes the prescaler 1. Note that I copied and pasted some code and played around with the parameters. TCCR2B = 0x1 //Timer2 Control Reg B: Timer Prescaler set to 1 TCCR2A = 0x00 //Timer2 Control Reg A: Wave Gen Mode normal TIMSK2 = 0x01 //Timer2 INT Reg: Timer2 Overflow Interrupt Enable TCNT2 = 255 //Reset Timer Count to 255 out of 255 TCCR2B = 0x00 //Disbale Timer2 while we set it up TIFR2 = 0x00 //Timer2 INT Flag Reg: Clear Timer Overflow Flag TCNT2 = 255 //Reset Timer to 255 out of 255 Timer2 Overflow Interrupt Vector, called every 1msĬount++ //Increments the interrupt counter Unsigned long count = 0 //used to keep count of how many interrupts were fired I've done a bit of surface deep research and cobbled together the following code: #include I'm trying to work out how to use the arduino uno to time things at its maximum frequency (16MHz), i.e.
0 Comments
Leave a Reply. |