Timer1 of pic 16f877a, the maximum frequency

[micropad]

Dear All
As per attached picture in Timer1 of pic 16f877a, the maximum frequency that can count in oscillator mode is from 0 to 200KHz please advice
View attachment 60732

 

[Gobbledok]

Hey have a look a little bit further up in the same table. That part of the table is only if you have an actual oscillator for Timer 1.

If you have an actual clock source (frequency input) then you are interested in the T1CKI input period.

For example lets say you have a standard 16F877a (rather than low voltage) and are using the counter in Synchronous mode with a prescale value of 4. Your minimum input period would be the greater of 30 nanoseconds or (TCY+40)/(Prescale Value). If you are running the chip at 20MHz, then your TCY = 200ns.

The equation then becomes (200+40)/4 = 60ns. 60ns input cycle time is equal to (1s/60ns) 16.667MHz maximum input freq.

HTH.

 

[micropad]

Dear Gobbledok
thank you so much for reply and you have been explain it in well manner

Hey have a look a little bit further up in the same table. That part of the table is only if you have an actual oscillator for Timer 1.

If you have an actual clock source (frequency input) then you are interested in the T1CKI input period.

For example lets say you have a standard 16F877a (rather than low voltage) and are using the counter in Synchronous mode with a prescale value of 4. Your minimum input period would be the greater of 30 nanoseconds or (TCY+40)/(Prescale Value). If you are running the chip at 20MHz, then your TCY = 200ns.

This Part is clear to me and thanks to you

The equation then becomes (200+40)/4 = 60ns. 60ns input cycle time is equal to (1s/60ns) 16.667MHz maximum input freq.

this part also clear and thanks
HTH.

finally I can underrated what is D and 200KHz mean as my picture . can you please explain using example
Please help me

 

[Gobbledok]

Dear Gobbledok
thank you so much for reply and you have been explain it in well manner

finally I can underrated what is D and 200KHz mean as my picture . can you please explain using example
Please help me

In you picture that is the specs if you are using an oscillator (such as a crystal). The oscillator can be anywhere from DC (0 Hz) to 200KHz.

 

[micropad]

In you picture that is the specs if you are using an oscillator (such as a crystal). The oscillator can be anywhere from DC (0 Hz) to 200KHz.

Dear sir thank you so much for reply

can you please explain me, how the delay reduce when we use prescaller WITH TIMER1

 

[Gobbledok]

How do you mean?


If you use a 1:2 prescale, that means it divides your clocks by 2. Likewise if you use a 1:8 prescale, that will divide your input clock by 8.