5. Delay Using Timers

5.1. Delay Calculation in Normal Mode 
 In Normal Mode , the timer always counts up to its maximum value and then overflows. To get a specific delay, you preload the TCNTn register with a starting value so it only has to count a specific number of steps before overflowing. 
 Here is the formula to find the required preload value : 
 
 For example, if we want to create a 1ms delay using Timer0 with 1/64 presacaler : 
 
 5.2. Delay Calculation in CTC Mode 
 In CTC (Clear Timer on Compare) Mode , the timer is much easier to use for delays because the hardware automatically resets the counter to zero when it reaches a target value stored in the OCRnx (Output Compare Register) . 
 Here is the formula to find the value to put in OCRnx register : 
 
 For example, if we want to create a 1ms delay using Timer0 with 1/64 presacaler :