Paul wrote:
>Hello everybody,
>I am having deficalty in getting the right dely to the clock i am using
>for my pic16f877.  which i am using 20MHz clock.  I have calculated a
>1msec as follows:
>
>I have a clock of 20MHz that meens 50nsec

No, this means 200ns. Each instruction takes 4, sometimes 8 (eg. goto)
clock cycles.
Cut down your multiplier by a factor of 4.

>then I have three instructions for each function so what i did is
>50nsec X 3inst X (how many time to be multiplied (n))= 1msec
>so,
>n = (1m X 20MHz) / 3inst = 6666.66666
>then,
>I devided that number by 100 to split it into two equations,  so I got 67
>and 100.
>
>the following is my iomplemented function,  however,  i am not getting the
>right delay.  I am geting larger delay
>
>
>
>Wait1ms
>         movlw   .67
>         movwf   temp11
>Wait1msB1
>         movlw   .100
>         movwf   temp12
>Wait1msB2
>         decfsz  temp12,1         ; this is one instruction
>         goto    Wait1msB2       ; this is two instructions which make 3 total
>         decfsz  temp11,1         ; the same here
>         goto    Wait1msB1
>         return

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics