Timers for

• ATmega328P used in Arduino Uno & Arduino Pro Mini
• ATmega2560 used in Arduino Mega 2560 and
• ATtiny85

are calculated in CTC mode. Select requested frequency, MCU and timer. Click Calculate. Copy result into the clipboard. Paste code into Arduino IDE. Ready. Click here for this easy to use tool.

It’s a good addition to my book Arduino Interrupts – Speed up your Arduino to be responsive.