Timers

Loviisa provides simple and quite common set of timer functionality. The easiest way is to use timers that create events.

LVS_DEFINE_TIMER(timer) defines new timer. Shall be used outside of functions in a global C context.

LVS_USE_TIMER(timer) lets you use the defined timer wherever you need it.

LVS_INIT_TIMER(timer, event, period, periodic) is to be executed in any initialization function or task before timer is used. This primitive sets timer's parameters, but doesn't start timer.

• timer - name of previously defined timer
• event - name of event that is generated when timer triggers
• period - time in milliseconds when timer is to be triggered
• periodic - 0 if timer shall be triggered once or 1 if it triggers periodically each milliseconds

LVS_START_TIMER(timer) launches the given timer

LVS_STOP_TIMER(timer) stops the timer

The following macros are used to obtain timer properties:

LVS_GET_TIMER_PERIOD_MS(timer) - retrieves timer's period in milliseconds LVS_GET_TIMER_EPOCH(timer) - how many times the timer was triggered LVS_IS_TIMER_ENABLED(timer) - is timer running right now LVS_IS_TIMER_PERIODIC(timer) - checks if timer is periodic

In addition to timers that provide events, tasks may use timeout functionality.

LVS_START_TIMEOUT(timeout_name) - starts counting time for the timeout

LVS_RESET_TIMEOUT(timeout_name) - stops counting time for the timeout

LVS_IF_TIMEOUT(timeout_name, ms) - the following block is executed if more than ms milliseconds passed since LVS_START_TIMEOUT. Timeout resets automatically. See conditional execution for more information about LVS_IF_... blocks, including LVS_IF_PASSED primitive that is very valuable for time-sensitive execution.

Important!

To make timers functionality working, user shall call the following function periodically using hardware/SDK timer or real time clock functionality, usually interrupt handlers:

void lvs_TimerTick(void);

The number of physical ticks per second (frequency of the system clock) is to be set in lvs_config.h as LVS_TICKS_PER_SECOND macro.

unsigned long lvs_GetTickCount(void); allows to obtain the current number of system ticks since the system start, but it is not recommended for a direct use.