tdquadros:
I need the interrupts to perform those blocks every second. If I use "delay" inside the loop, I lose the lamp reference and it starts to blink.
Since every 1 second is super slow, you had better using millis() (and not delay, see blink without delay, this is a non blocking code), you definitely don't need a timer trigger for that.
What frequency do you need for the PWM pulse ?