setting a config in 16F877A

[Transistorman]

hi
today is my first time i connect my 877A
to my pickit2 , and now i need some help
on changing the config line the c code
here is the code

#include <system.h>

#pragma CLOCK_FREQ 4000000  // config clock to 4mhz.

// Set configuration fuse.

[COLOR="red"]#pragma DATA _CONFIG, _XT_OSC & _WDT_OFF & _CP_OFF & _PWRTE_OFF[/COLOR]

void main()
{
   trisb = 0;        //configure port B pins as output
   while( 1 )      //endless loop
   {
     portb.0=1;        // set portb pin0 to high.
     portb.1=0;        // set portb pin1 to low.
     delay_ms( 500 );  // pause 0.5 seconds
     portb=0x02;       // shows hex notation for entering data.
     delay_ms(500);    // you can also write portb=2 in decimal
   }
}

the red line is the thing i confused on
please help me !
also ,
is 877A have internal clock ?
because i run out of crystal

 

[ericgibbs]

hi,
No internal oscillator.

 

[Transistorman]

hi eric
what about if i using resistor for clock
as it shown on the attachment ?

 

[ericgibbs]

hi eric
what about if i using resistor for clock
as it shown on the attachment ?

hi,
You could do that, change that CONFIG to suit an RC osc.

EDIT:

 

[Transistorman]

where did the OSC2 pin go ?

 

[ericgibbs]

hi,
Its just an output = Freq/4

 

[Transistorman]

hi can i use 22 pF capacitor and 10k resistor ?

 

[ericgibbs]

hi can i use 22 pF capacitor and 10k resistor ?

That should work according to the datasheet, what frequency are you expecting.?

 

[Transistorman]

4 megaherzt

 

[ericgibbs]

4 megaherzt

I make it about 4.5mHz, close enough I guess.

 

[Transistorman]

hi
what about if i using 33pF capacitor with 10k - 100 k resistor ?

 

[ericgibbs]

hi
what about if i using 33pF capacitor with 10k - 100 k resistor ?

hi,
With a 33pF and a 7k5 I make it 4.04mHz [use two 15K in parallel]

 

[Transistorman]

so i need to set the the set clock to 4040000 , right ?

 

[Pommie]

If you swap to a 16F887 then it has an internal clock.

Mike.

 

[ericgibbs]

so i need to set the the set clock to 4040000 , right ?

hi,
Unless you are doing something thats time critical, setting it at 4hHz would be ok, or as suggested change the PIC type.