The fpTimer unit implements a timer class TFPTimer which can be used on all supported platforms. The timer class uses a driver class TFPTimerDriver which does the actual work.
A default timer driver class is implemented on all platforms. It will work in GUI and non-gui applications, but only in the application's main thread.
An alternative driver class can be used by setting the DefaultTimerDriverClass variable to the class pointer of the driver class. The driver class should descend from TFPTimerDriver.