How can I simulate "count" in pic basic pro with C

ROBOTICAR · Joined: 28 Aug 2007 Posts: 45

Hi all

How can I simulate "count" in pic basic pro with CCS.
I need a source code for count the puls in the specific pin.
Do you get me a program with TMR0 (for example in 16f84a)?

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Tell us the purpose of your program. There may be a better way to
do it than duplicating the PBP Count function. Give some details about
the project and the input signal.

ROBOTICAR · Joined: 28 Aug 2007 Posts: 45

My input signal is pulse (around 10KHz to 100KHz) and I need a program for measuring this frequency.This program must very exact.
for example:when the original pulse frequency is 15KHz I want this frequency counter represent exactly 15KH .(Not 14.9KH or Not15.1KH)
Do you help me?

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

This thread shows how to use the CCP to make a tachometer.
http://www.ccsinfo.com/forum/viewtopic.php?t=29963

100 KHz has a 10 us period. That's too fast to use with interrupts
for most PIC oscillator frequencies. So, you would need to use a
divisor on the CCP input. Probably use CCP_CAPTURE_DIV_4,
or CCP_CAPTURE_DIV_16, which would increase the interrupt
interal to 40 us or to 160 us. It would depend upon your PIC oscillator
frequency. You may have to use a 24-bit timer (Timer1 with 8-bit
software extension). This is described in the link above.

ROBOTICAR · Joined: 28 Aug 2007 Posts: 45

Thanks for your help but this part, is a article of PBP HELP

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

If you want to use the Count function, then compile a small test program
in PBPro, and look at the .LST file in the PBPro project directory.
It will have commented listing of the MPASM code that's used to create
the Count function. I did this, and the code is posted below.

Next, learn how to read ASM code, and translate it to CCS C source code.
Here's an example where someone did this for the POT command:
http://www.ccsinfo.com/forum/viewtopic.php?t=27191

I don't want to do the translation. I don't have the time. I did the Button
comand and posted it in the Code Library. I don't have time to do any
more of them.

ROBOTICAR · Joined: 28 Aug 2007 Posts: 45

Can you tell me :How many cycle(s) last each statement ?(1cycle ,2 cycle or...)
IF,FOR(),WHILE ,BREAK,CONTINUE,I++

Thanks for reply

anestho · Joined: 27 Dec 2006 Posts: 28

I think that branching and goto's require 2 cycles, while everything else is 1 cycle.

Cycles can only apply to ASM not C. An "if" statement may be 3 ASM instructions or 10, depending on the conditional statement. If you want to know, compile a test code, and look at the .lst file to see how many instructions it takes in ASM.