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Real Basic Question pic microcontrollers

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Miltaridis

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I am using a 18f4550 pic and i micro c pro. I have a digital waveform coming out of a flip-flop circuit and i want to be able to measure it in one of pic's digital inputs. How can i do this:lol:?
Moreover if someone could kindly explain.
How is the waveform's clock found ?
What must the frequency of the waveform be?

Thank you in advance :)
 

Hi,

You use the CCP module of the Pic, plenty of tutoriuals and examples in Micro C in the forum and web

- - - Updated - - -

Hi,

You use the CCP module of the Pic, plenty of tutoriuals and examples in Micro C in the forum and web
 
Well really appreciate your help and time. But i rather feel confused from all these information without an easy example.

What is the use of the digital inputs if you need to use ccp module ?

Cant i feed a digital signal with known frequency into a digital input ?

I see that some pins have an interrupt on change register. Can this be used to identify a waveform?

If anyone could kindly elaborate a bit more on this i would be gratefull.

Thanks in advance
 
Last edited:

Hi,

That ccp module does explain things but not always clearly for a beginner.

You do feed the signal into a digital input, but you have to have a reference timer / a counter to the number of machine cycles for your signal to run against, its the only way you can determine the length of the pulse.

I don't do Mikro C but if you google on 'ccp tutorial in mikro C' it returns a lot of entries including many posts in the eda forum.
https://www.mikroe.com/forum/viewtopic.php?t=7025
https://www.edaboard.com/threads/261765/
https://www.microchip.com/forums/m478237.aspx
 
You could make a simple frequencimeter with the microcontroller.

Using the 16f877A as example:

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[CODE]
//Using 20MHz clock
#include <16F877.h>
#use delay(clock=20M)
 
boolean a;
int32 rise, rise2, value;
float freq, period;
 
#int_ccp1
void isr2()
{
  rise=CCP_1; 
} 
 
#int_ccp2
void isr()
{
  rise2 = CCP_2;
  value = rise2 - rise;
  a=1;
} 
void main()
{
   #priority ccp2,ccp1
   setup_ccp1(CCP_CAPTURE_RE); // Configure CCP1 to capture rise
   setup_ccp2(CCP_CAPTURE_RE); // Configure CCP2 to capture rise
   setup_ccp2(CCP_CAPTURE_DIV_4);
   setup_timer_1(T1_INTERNAL); // Start timer 1
   enable_interrupts(INT_CCP2); // Setup interrupt on falling edge
  enable_interrupts(INT_CCP1); // Setup interrupt on falling edge
  enable_interrupts(GLOBAL);
  a=0;
  while(TRUE) 
  {
    if(a==1)
    {
      period=value/5; //Doesn't need to divide if 4MHz
      if(period<1000)
      {
        freq=1000000/period;
        freq=freq/1000;
      }
      else
      {
        freq=1000000/period;
      }
 
      a=0;
    } 
  }
}
[/CODE]
 
Thanx for the insight .

I am thinking on using the interrupt on change feature on port B of pic18f4550 .

Will get back to you when need arise8:-D
 

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