Timer functions [IoUtil Functions]

Starting, stopping and execution of time triggered actions.

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Data Structures
struct	time_stamp_t
Defines
#define	MSEC(v)   ((time_t)(v / (1.0e3 * TIMER_TICK)))
#define	NONE_TIMER   (0)
#define	USEC(v)   ((time_t)(v / (1.0e6 * TIMER_TICK)))
Typedefs
typedef uint32_t	time_t
typedef uint32_t	timer_arg_t
typedef time_t(	timer_handler_t )(timer_arg_t p)
typedef uint16_t	timer_hdl_t
Functions
void	timer_get_tstamp (time_stamp_t *ts)
void	timer_init (void)
	Initialization of the timer module.
timer_hdl_t	timer_restart (timer_hdl_t th, time_t duration)
	Restarting a running timer.
void	timer_set_systime (time_t sec)
	Set the current system time given in seconds since 1.1.1970.
timer_hdl_t	timer_start (timer_handler_t *thfunc, time_t duration, timer_arg_t arg)
	Start a timer with a given handler function.
timer_hdl_t	timer_stop (timer_hdl_t th)
	Stop a running timer.
time_t	timer_systime (void)
	Return the current system time in ticks.

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Detailed Description

Starting, stopping and execution of time triggered actions.

This group of functions provides a one shot timer implemenation.

It is inspired by Jörg Wunschs timer implementation, which can be found here: http://sax.sax.de/~joerg/avr-timer/

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Define Documentation

#define MSEC

(

v

)

((time_t)(v / (1.0e3 * TIMER_TICK)))

Macro that converts the millisecond value v into TIMER_IRQ_vect ticts

#define NONE_TIMER   (0)

Symbolic name for invalid timer handle

#define USEC

(

v

)

((time_t)(v / (1.0e6 * TIMER_TICK)))

Macro that converts the microsecond value v into TIMER_IRQ_vect ticts

---

Typedef Documentation

typedef uint32_t time_t

Data type for time values (measured in number of system ticks).

typedef uint32_t timer_arg_t

Data type for the argument of a timer handler function.

typedef time_t( timer_handler_t)(timer_arg_t p)

Data type for timer expiration action function. This function is called, when the expiration time is over. When luanched, the function is called with a parameter p of type .timer_arg_t. If the function returns a value, which is greate then 0, the timer is restarted again.

typedef uint16_t timer_hdl_t

Data type for a timer handle (a reference number to identify a running timer).

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Function Documentation

void timer_get_tstamp

(

time_stamp_t *

ts

)

Function that returns the internal system time counters as "libpcap" compatible time stamp.

Note:

This routine takes ~548 cycles for execution. In case of a 8Mhz driven system, this is a 68.5 us.

Parameters:

ts

timestamp data structure

void timer_init

(

void

)

Initialization of the timer module.

timer_hdl_t timer_restart	(	timer_hdl_t	th,
		time_t	duration
	)

Restarting a running timer.

If the timer is found in the timer queue, then it is rstarted with the new duration value.

Parameters:

	th	Handle of the timer. The timer needs to exist in the timer queue, e.g. it is started with timer_start() and not yet expired.
	duration	time in system ticks from now, when the timer expires.

Returns:

the value of NONE_TIMER if the timer could not be found in the timer queue. Otherwise the value of th.

void timer_set_systime

(

time_t

sec

)

Set the current system time given in seconds since 1.1.1970.

timer_hdl_t timer_start	(	timer_handler_t *	thfunc,
		time_t	duration,
		timer_arg_t	arg
	)

Start a timer with a given handler function.

This function initially creates a timer and assigns a timer handle to it. The timer handle is reference number, which identifies the timer uniquely and is needed for restart and stop a running timer.

Parameters:

	thfunc	pointer to a function, which is called when the timer expires.
	duration	time in system ticks from now, when the timer expires.
	arg	argument, which is passed to the timer function.

Returns:

the value of NONE_TIMER if the timer could not be started. Otherwise a handle != NONE_TIMER, which is needed for restarting and stopping the timer.

timer_hdl_t timer_stop

(

timer_hdl_t

th

)

Stop a running timer.

Parameters:

th

Handle of the timer. The timer needs to exist in the timer queue, e.g. it is started with timer_start() and not yet expired.

Returns:

the value of NONE_TIMER if the timer could not be found in the timer queue. Otherwise the value of th.

time_t timer_systime

(

void

)

Return the current system time in ticks.