Hello;
The count parameter of that function only is concidered when either a pulse or pulse train generation is configured at the counter.
In that case, that parameter is the number that will be divided by the TimeBase chosen, so the period of the pulses will be defined. To get more familiar on how that function is used, take a look at the 8253*.c examples, you will see that parameter specified as zero at the event counting examples and as a different number at the pulse generation examples.
Hope this helps.
Filipe
