CODEWITHSUNDEEP
c++windowsvisual-c++timeroperating-system
rahul jv
rahul jv

Reputation: 19

High precision event timer

#include "target.h"
#include "xcp.h"
#include "LocatedVars.h"
#include "osek.h"


/**
 * This task is activated every 10ms.
 */
long OSTICKDURATION;
TASK( Task10ms )
{
    void XCP_FN_TYPE Xcp_CmdProcessor( void );
    uint32 startTime = GetQueryPerformanceCounter();

    /* Trigger DAQ for the 10ms XCP raster. */
    if( XCPEVENT_DAQ_OVERLOAD & Xcp_DoDaqForEvent_10msRstr() )
    {
        ++numDaqOverload10ms;
    }

    /* Update those variables which are modified every 10ms. */
    counter16 += slope16;

    /* Trigger STIM for the 10ms XCP raster. */
    if( enableBypass10ms )
    {
        if( XCPEVENT_MISSING_DTO & Xcp_DoStimForEvent_10msRstr() )
        {
            ++numMissingDto10ms;
        }
    }



    duration10ms = (uint32)( ( GetQueryPerformanceCounter() - startTime ) / STOPWATCH_TICKS_PER_US );
}

What would be the easiest (and/or best) way to synchronise to some accurate clock to call a function at a specific time interval, with little jitter during normal circumstances, from C++? I am working on WINDOWS operating system now. The above code is for RTAS OSEK but I want to call a function at a specific time interval for windows operating system. Could anyone assist me in c++ language ??

Upvotes: 2

Views: 2702

Answers (2)

Arno
Arno

Reputation: 5194

New applications should use CreateTimerQueueTimer!

Timers in this queue, known as timer-queue timers, are lightweight objects that enable you to specify a callback function to be called when the specified due time arrives. The wait operation is performed by a thread in the thread pool.

CreateTimerQueueTimer function. Example: Using Timer Queues (C++).

However, the granularity is about 1ms, a setup of 10 ms may cause periodic hiccups at 9/11 ms.

For higher resolution you may have to setup a timer wheel using Clock::now() as described here.

Upvotes: 2

ScottMcP-MVP
ScottMcP-MVP

Reputation: 10415

The timeSetEvent API will give you the best stability available, and it can go down to as low as 1 millisecond intervals.

Upvotes: 1

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