Problem to measure time period

[kalisaitan]

I want to measure the frequency of the square wave input at RA0 of PIC16F877A.
So how should i start writing the code in C for CCS compiler??
Crystal frequency is 1MHz.
THANKS

[Mike Walne]

1) Have a go yourself, post code here when/if you get stuck.
2) Read the forum guidelines.
3) Tell us the frequency range of your signals.
4) Search here and google for similar code, it's been done before.


Mike

[asmboy]

consider using either the CCP circuit
or the timer1 ext input with a gate from timer0

you may need a prescalar depending on frequency..
and your crystal frequency may be too low for higher input freq counts.

all these factors are inter related

thats my hardware advice
now per Mike
get coding..........

[Ttelmah]

Look at EX_FREQC.C. Except for having to change the clock (it is setup to use 20MHz), this is a complete example of how to do this. Except using the CCP input not RA0. Trying to do it on RA0, would limit the possible frequency supported to only a few hundred Hz.

Best Wishes

[Mike Walne]

Try this as a link for starters.

http://www.ccsinfo.com/forum/viewtopic.php?t=47653&start=0&postdays=0&postorder=asc&highlight=exfreq

Mike

[kalisaitan]

thanx but i am beginner in programming,
i have no concept actually how code works

[PCM programmer]

If you don't know anything about code or electronics or anything, you
shouldn't be asking questions on the forum at this point in time.
You should be looking at tutorials on the net:

Here's a video by CCS on how to use their compiler to write a program:
http://www.ccsinfo.com/videos/QuickStartVideo.wmv

Also you should answer questions that people ask you, such as what is
the range of input frequencies that you want to measure ?

[kalisaitan]

i mean i understand about basic programming.But
I have no such concept about to measure Time period..

i want to measure frequency range of about 40 to 80 Hz

[ezflyr]

kalisaitan,

Do you actually own the CCS 'C' compiler? In your first post, locked and now deleted, you asked for help writing a 'Hi-Tech C' program. Suddenly,
a few hours later, you posed the exact same question, but this time you switched your query to the CCS compiler. You have been referred to the
CCS example programs, and other resources, but up to now, you haven't shown that you have actually done anything on your own. Personally, I think
you are trying to get us to do your homework assignment, and you have no actual interest in learning PIC programming.

John

[asmboy]

the concept you need to solve this is for frequency/period/time:

T=1/F

you do understand that right ?

and the examples already cited ought to give you guidance.
have you read them yet?

[gpsmikey]

Since you mention "40-80hz", it sounds like measuring power line frequency. You don't mention accuracy, but if you are intending to read that to several digits to the right of the decimal, you need to consider measuring over multiple waves and taking the average or some other way of accurately measuring the time as well as how you are going to accurately measure the "period" of the wave (zero crossing or ??? )

mikey
_________________
mikey
-- you can't have too many gadgets or too much disk space !
old engineering saying: 1+1 = 3 for sufficiently large values of 1 or small values of 3