Event Register

 

Introduction to Real time operating system(RTOS)

 

Event Registers •

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A task can have an event register in which the bits correspond corr espond to dierent events! It is a "#$bit event register  These "#$bit are divided into %our portions corresponding corr esponding to events o% three tasks and one ISR! Each o% the bits in the event register is an event &ag! A task can have an event register and other task can set'clear the bits in the event register to in%orm the status o% an event!  The meaning o% " or  %or particular bit has to be decided be%orehand!

 

Event register(contd!!) •

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 Task can set the *rst %our bits to " or !  Task +sing predetermined protocol protocol the meaning %or each o% these bits is decided!  Task  T ask " comes to know the status o% events %rom these bits!

 

Event Register ,anagement -unction .alls

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-or managing the event registers/ the %ollowing %unction calls are provided0 

.reate an event register 1elete an event register 

2uery an event regist register er Set an event &ag .lear an event &ag

 

 TI,ERS  Timers are used to measure the elapsed time o% events! -or instance/ the kernel has to keep track o% dierent times0  A particular task may need to e3ecuted periodically/ say every " msec! A timer is used to keep track o% this periodicity!  A task may be waiting in a 4ueue %or an event to occur! I% the event does not occur %or a speci*c time/

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it has to take appropriate action!  A task may be waiting in a 4ueue %or a shared resource! I% the resource is not available %or a speci*c time/ an appropriate action has to be taken!

 

 Timer  T imer ,anagement %unction  The %ollowing %unction are .alls calls are provided to manage the timer0  5et time  Set time  T  Time ime 1elay(in system clock ticks) •

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 Time delay (in seconds)  Time  Reset timer

 

,emory ,anagement ,emory management is an important service provided by the ker kernel! nel!  The A6I provides the %ollowing %unction calls to manage memory0  .reate a memory block!  5et 1ata %rom memory!  6ost data in the memory!  2uery a memory block  -ree the memory block

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