PIC 16F877A for rotation counter programme. i need it badly.

[Adrian HZW]

PIC 16F877A

Hi,
I have a problem where i don't how to write a program for my rotation counter.
My system is a rotation counter, It count decrementally. does anyone here can help me on the programming part?

Thank you.

 

[keith1200rs]

You question is very vague. Are you simply using the PIC for counting something?

Keith

 

[Adrian HZW]

Keith,

No, im not simply using PIC, i only provided with PIC16F877A for create rotation counter project. and the sensor i used is magnetic sensor.

Adrian

 

[keith1200rs]

If you are simply counting then you can use one of the timer modules which can count from an external pin. If you want to measure pulse rate then the capture mode may be more appropriate. Do you have a schematic? You will need to ensure you have a clean input signal to prevent miscounting.

Keith

 

[jayanth.devarayanadurga]

Is your magnetic sensor a hall effect sensor or reed switch type? If the sensor gives pulse outputs then feed that pulse to RB0/INT pin and use PORTB interrupt to get the values of rotations. If one pulse is given for every rotation then interrupt occurs for every rotation, so, no. of interrupts is the no. of rotations.

 

[Adrian HZW]

hi jayan,

my magnetic sensor will generate 1 output signal when it detects metal passing by.
and my condition which i would like to declare is

// define
#define sensor D1
#define Led G D2
#define Led Y D3
#define Led R D4
#define Push Button D0

is this correct? and im using PIC C compiler s/w.


-adrian-

 

[War]

If the sensor gives you a pulse, you can use the CCP module for a precise value.
Made a frequencimeter with the CCP module in this post.
Modified to give the RPM.

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//Using 20MHz clock
#include <16F877.h>
#use delay(clock=20M)
 
boolean a;
int32 rise, rise2, value;
float freq, period, rpm;
 
#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;
        rpm=freq*60;
      }
      else
      {
        freq=1000000/period;
      }
 
      a=0;
    } 
  }
}

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