void cyg_alarm_create
(
  cyg_handle_t   counter,  /* counter to attach to alarm      */
  cyg_alarm_t    *alarmfn, /* alarm call back function        */
  cyg_addrword_t data,     /* data to be passed to callback   */
  cyg_handle_t   *handle,  /* returned handle to alarm object */
  cyg_alarm      *alarm    /* alarm object                    */
)

When the alarm expires "*alarmfn" is called with "data" as an argument. Alarms can be setup to be recurring or to execute only once.

The callback "alarmfn" is of the form: void cyg_alarm_fn(Cyg_Alarm *alarm, CYG_ADDRWORD data).

The newly created alarm is written to "*handle".

void cyg_alarm_delete
(
  cyg_handle_t alarm /* alarm to delete */
)

void cyg_alarm_initialize
(
  cyg_handle_t     alarm,   /* handle of alarm to initialize */
  cyg_tick_count_t trigger, /* absolute trigger time         */
  cyg_tick_count_t interval /* re-trigger interval           */
)

If the alarm is to be triggered at a regular interval, "interval" can be set to a non 0 value.

When the trigger fires the alarm function associated with the alarm will be called.

void cyg_alarm_get_times
(
  cyg_handle_t     alarm,    /* alarm to get the times of   */
  cyg_tick_count_t *trigger, /* next trigger time           */
  cyg_tick_count_t *interval /* current re-trigger interval */
)

void cyg_alarm_enable
(
  cyg_handle_t alarm /* alarm to re-enable */
)

A periodic alarm that has been disabled and later re-enabled will fire at the same intervals it did previously. For example, a periodic alarm that fired every 10 seconds at time T0, T10, T20, T30... etc that was disabled for 15 seconds at time T31 and then re-enabled would then start firing again at T50, T60, T70 etc.

You can call cyg_alarm_initialize if you want to reset the periodic interval.

void cyg_alarm_disable
(
  cyg_handle_t alarm /* alarm to disable */
)