Echelon Neuron C - Manual (Page 178)

158 Timer Declarations
Timer Object
A timer object is declared using one of the following:
mtimer [repeating] timer-name [ =initial-value ];
stimer [repeating] timer-name [ =initial-value ];
mtimer Indicates a millisecond timer.
stimer Indicates a second timer.
repeating An option for the timer to restart itself automatically
upon expiration. With this option, accurate timing
intervals can be maintained even if the application cannot
respond immediately to an expiration event.
timer-name A user-supplied name for the timer. Assigning a value to
this name starts the timer for the specified length of time.
Assigning a value of zero to this name turns the timer off.
The value of a timer object is an unsigned long (0..65535);
however, the maximum value assigned to a millisecond
timer cannot exceed 64000. A timer that is running or
has expired can be restarted by assigning a new value to
this object. The timer object can be evaluated while the
timer is running, and it indicates the time remaining. Up
to 15 timer objects can be declared in an application.
initial-value An optional initial value to be loaded into the timer on
power-up or reset. Zero is loaded if no initial-value is
supplied (and therefore the timer is off).
When a timer expires, the timer_expires event becomes TRUE. The
timer_expires event returns to FALSE after the timer_expires expression is read,
or when the timer is set to zero.
Example:
stimer led_timer = 5; // start timer with value of 5 sec
when (timer_expires(led timer))
{
toggle_led();
led_timer = 2; // restart timer with value of 2 sec
}
The timers_off( ) function can be used to turn off all application timers – for
example, before an application goes offline. See Chapter 2, Focusing on a Single
Device, of the Neuron C Programmer's Guide for a discussion of timer accuracy.