diff --git a/firmware/main.c b/firmware/main.c
index 9e30e15..2e80d08 100644
--- a/firmware/main.c
+++ b/firmware/main.c
@@ -54,7 +54,7 @@ void init()
     sei(); // Enable interrupts global
 }
 
-/*! \brief TIMER1 interruptvector
+/*! \brief TIMER1 interruptvector, called in a frequency of 300Hz.
  */
 ISR (TIMER1_COMPA_vect)
 {