High Resolution Timer Improve performance with high-precision timers for operating systems Application areas The High Resolution Timer is designed for applications requiring high-precision timers but in which additional interrupt loads are unacceptable. An important property of operating systems is the precision of alarms; this in turn affects the resulting interrupt load. The alarm mechanism of an OSEK/VDX or AUTOSAR operating system is based on counters which are incremented by either software or hard-ware timers. When a counter reaches a preset alarm value, a pre-defined Hardware requirements The High Resolution Timer can be used on all microcontrollers which have a free-running timer. The timer must also be able to trigger an interrupt when its value matches a user-definable com-pare action is executed. The typical time resolution of such timers is 1 ms. If timer resolutions with a higher precision than 1 ms are required, the High Resolution Timer mechanism can achieve these enhan-ced value (compare-match). The clock speed at which the hard-ware timer is operated should be adjustable so that the desired precisions without simultaneously increasing interrupt load. Resolutions in the microsecond range are possible depending on the controller used. level of accuracy is achieved. Configuration The High Resolution Timer is configured using the configuration tool for the Vector operating systems. This tool is used to adjust the prescalers according to the clock frequency of the microcon-troller. Features and advantages The High Resolution Timer for the osCAN and MICROSAR OS oper-ating systems permits high-precision alarms with low system 4/4 interrupt load (depending on hardware). An interrupt is only triggered when an alarm actually becomes due. The precision of the alarm time depends only on the resolution and clock frequency of the hardware timer. It may range from 100 ns to 100 μs depending on the microcontroller. ◆ Functions “Collective” processing of several consecutive alarms can be con-trolled by defining a minimum interval between timer interrupts. This reduces interrupt load, especially when several alarms with similar intervals expire almost simultaneously. Alarms and Tasks