From user guide:
When the timer n is in idle state, writing a non-zero value IVALUE to the INTVALn register
immediately loads the time interval value IVALUE - 1, and the timer begins to count down
from this value. When the timer reaches zero, an interrupt is generated, the value in the
INTVALn register IVALUE - 1 is reloaded automatically, and the timer starts to count down
Too many words here, but how exactly to calculate period T of generated interupt sequence for given IVALUE ?
It is not clear from all words spent above.