compare mode calculation of ccp module

[deepa.malagi]

Hi everybody,

I am using pic16f4585,I have to generate frequency of 28.31Hz signal using compare mode of ccp module.

Please help me how to calculate CCPR1 value, I am not getting how to calculate it.using internal frequency 8MHz.

Please help me..........

 

[Wond3rboy]

There is no chip by the name 16f4585.

 

[Ian Rogers]

He must mean pic18f4585.

Ian

 

[Wond3rboy]

Deleted because i stood corrected.

 

[Ian Rogers]

Why do you need to use CCP? 28.31hz equates to 35.32 ms thats very easy to generate using delays, 17.66ms on 17.66ms off

Cheers Ian

 

[Mr RB]

CCP compare value = 8Mhz / 4 / 28.31Hz / 2
(note the /2 is needed as you will be toggling the output pin at double 28.31Hz)

therefore;
CCP compare value = 8Mhz / 4 / 28.31Hz / 2 = 35323

Assuming you are using an CCP capture interrupt there will be a small interrupt latency between entering the int routine and actually toggling the output pin, a latency of maybe 10 or 15 PIC instructions, so you need to do;
35323 - 10

Then check it on a frequency meter to fine tune the exact frequency.

 

[deepa.malagi]

Thank all
I tried this it's working thank you all.