Datasheet

If a write is performed to any of the five timer/counter2 registers while its update busy flag is set, the
updated value might get corrupted and cause an unintentional interrupt to occur.
Related Links
13.9 Timer/Counter Oscillator
ATmega48PA/88PA/168PA
8-bit Timer/Counter2 (TC2) with PWM and A...
© 2018 Microchip Technology Inc.
Datasheet Complete
DS40002011A-page 225