Coarse Timer

Detailed Description

A coarse global timer that can be used to track time intervals.

The timer is accurate to 10ths of a millisecond.

Files
file	coarse_timer.h
	Provides a coarse timer for determining the elapsed time between two events.

Data Structures
struct	CoarseTimer_Settings
	Settings for the CoarseTimer module. More...

Typedefs
typedef uint32_t	CoarseTimer_Value
	An opaque type used to represent a time stamp.

Functions
void	CoarseTimer_Initialize (const CoarseTimer_Settings *settings)
	Initialize the timer. More...
void	CoarseTimer_TimerEvent ()
	Update the timer. More...
CoarseTimer_Value	CoarseTimer_GetTime ()
	Get the current value of the timer. More...
uint32_t	CoarseTimer_ElapsedTime (CoarseTimer_Value start_time)
	Return the interval since the start_time. More...
uint32_t	CoarseTimer_Delta (CoarseTimer_Value start_time, CoarseTimer_Value end_time)
	Return the interval between two times. More...
bool	CoarseTimer_HasElapsed (CoarseTimer_Value start_time, uint32_t interval)
	Check if a time interval has passed. More...
void	CoarseTimer_SetCounter (uint32_t count)
	Manually set the internal counter. More...

Function Documentation

uint32_t CoarseTimer_Delta	(	CoarseTimer_Value	start_time,
		CoarseTimer_Value	end_time
	)

Return the interval between two times.

Parameters

start_time	The time to measure from.
end_time	The time to measure to.

Returns

The time between the start and end time, measured in 10ths of a millisecond.

Accuracy is to within 10ths of a millisecond. Be careful if using this to trigger events. as the events may then trigger up to 0.1ms before they were supposed to.

uint32_t CoarseTimer_ElapsedTime

(

CoarseTimer_Value

start_time

)

Return the interval since the start_time.

Parameters

start_time

The time to measure from.

Returns

The time since the start_time, measured in 10ths of a millisecond.

Accuracy is to within 10ths of a millisecond. Be careful if using this to trigger events. as the events may then trigger up to 0.1ms before they were supposed to.

CoarseTimer_Value CoarseTimer_GetTime

(

)

Get the current value of the timer.

Returns

The current value of the timer counter.

The value returned can be later passed to CoarseTimer_HasElapsed() and CoarseTimer_ElapsedTime().

bool CoarseTimer_HasElapsed	(	CoarseTimer_Value	start_time,
		uint32_t	interval
	)

Check if a time interval has passed.

Parameters

start_time	The time to measure from.
interval	The time interval in 10ths of a millisecond.

Returns

true if the interval has elapsed since the start_time.

void CoarseTimer_Initialize

(

const CoarseTimer_Settings *

settings

)

Initialize the timer.

Parameters

settings

The timer settings.

The settings should match the interrupt vector used to call CoarseTimer_TimerEvent().

Example

CoarseTimer_Settings timer_settings = {
  .timer_id = TMR_ID_2,
  .interrupt_source = INT_SOURCE_TIMER_2
};

CoarseTimer_Initialize(&timer_settings);

void CoarseTimer_SetCounter

(

uint32_t

count

)

Manually set the internal counter.

Parameters

count

the new value of the internal counter.

Note

This function should be used for testing only.

void CoarseTimer_TimerEvent

(

)

Update the timer.

This should be called from within an ISR.

Example

void __ISR(_TIMER_2_VECTOR, ipl6) TimerEvent() {
 CoarseTimer_TimerEvent();
}

The interrupt vector should match what was supplied to CoarseTimer_Initialize().