Hi All, need helps
T0CKI High Pulse Width delay exist 0.5TCY + 20 (No Prescaler) and With Prescaler 10ns. I can not understand the mechanism how delay reduce with Prescaler, please explain

 

Take a deep look at your TIMER0 WITH SHARED PRESCALE BLOCK DIAGRAM.

When T0CKI is not used with the prescaler there is a Synchronizing circuit based off Fosc/4. That needs a minimum hi or low time to capture the input.

When the prescaler output is naturally a square wave so there is one less factor to consider.

 

Take a deep look at your TIMER0 WITH SHARED PRESCALE BLOCK DIAGRAM.

When T0CKI is not used with the prescaler there is a Synchronizing circuit based off Fosc/4. That needs a minimum hi or low time to capture the input.

When the prescaler output is naturally a square wave so there is one less factor to consider.

Dear ErnieM
Thanks a lot for clear reply
as per your reply, if we insert square wave to TOCKI with out prescaler. what do you think
Thanks in advance

 

Then the T0CKI Period spec must still be met, which is Tcy+20nS.

So it depends on the clock (Fosc) you are using on that device. (Tcy = 4/Fosc)