# timer.start

timer.start is a function that is part of the timer functions.

This fucntion starts the timer with the given period in seconds.
This means that the this function fires the on.timer() event (that you have to define with a function in your code) will be called every x seconds, according to the period given in the parameter.
If the timer is already running when this routine is called, the timer is reset to the new period.

This has been introduced in TI-Nspire OS 3.0 (Changes).

## Syntax

timer.start(period)

Parameter Type Description
period
number the time period in seconds for the timer to start. Must be > 0.01

## Example

This example will display on the top-left corner of the screen a number going from 0 to infinity (it never stops), by adding 1 to variable every 0.5 seconds.

variable = 0

function on.timer()
timer.stop()  -- stops the current timer. Not necessary.
variable = variable + 1
platform.window:invalidate()  -- screen refresh (on.paint is called)
end

function on.paint(gc)
timer.start(0.5)  -- will fire the on.timer event every half second.
gc:drawString(variable,0,0,"top")  -- display the number
end