RtSetHalTimerPeriodCounts

RtSetHalTimerPeriodCounts sets the APIC counts per eRTOS HAL timer period.

Syntax

bool RtSetHalTimerPeriodCounts(
    ULONG PeriodicCounts
);

Parameters

PeriodicCounts

Specifies a new value for the APIC counts per eRTOS HAL timer period.

Return Value

If the function succeeds, it returns true. Otherwise, it returns false. Call GetLastError for additional error information.

Remarks

RtSetHalTimerPeriodCounts allows you to set a new value for the APIC counts per HAL timer period, therefore adjusting the reference frequency of the APIC timer. The HAL timer is used for all other timers or clock-related functions. Adjusting the HAL timer period count will affect the entire system, not just the calling application.

To adjust time, call RtGetHalTimerPeriodCounts to obtain the current APIC counts and the base APIC counts. To adjust time to run slower, increase the APIC counts and call RtSetHalTimerPeriodCounts to set on APIC timer. To adjust time to run faster, decrease the APIC counts and call RtSetHalTimerPeriodCounts to set on APIC timer. The new count can either be calculated by multiplying or dividing a percentage of the current APIC counts, or by incrementing/decrementing certain counts on the current APIC counts.

To avoid significant side effects on timers and timing-relative RTAPIs (processed by HAL ticks), the adjustment of the APIC counts should not be less than 90% or greater than 110% of the base APIC counts. Otherwise, RtSetHalTimerPeriodCounts returns FALSE and GetLastError returns ERROR_INVALID_PARAMETER.

Below is a matrix of the Real-Time APIs that are impacted by adjusting APIC Counts per HAL Timer Period:

Below is a matrix of the eRTOS program samples that are impacted by adjusting APIC Counts per HAL Timer Period:

See Also:

• RtGetHalTimerPeriodCounts