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PIC16F877A int_ext

 
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Khansokhua



Joined: 06 Nov 2021
Posts: 45

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PIC16F877A int_ext
PostPosted: Sat Nov 27, 2021 4:07 am     Reply with quote

Code:
#include <Timerlar.h>
#fuses XT
#use delay(clock=4M)
#use fast_io(b)
int i;
const int segment[10]= {0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7C,0x07,0x7F,0x6F};

#int_ext
void ext_kesme()
{
   output_high(pin_d0);
   delay_ms(1000);
   output_low(pin_d0);
   delay_ms(3000);
   
   for(i=0;i<=9;i++)
   {   
        output_c(segment[i]);
        output_high(pin_d0);
        delay_ms(500);
        output_low(pin_d0);
        delay_ms(500);   
   }

}


void main()
{   
  set_tris_b(0x01);
   
   output_c(0x00);
   output_d(0x00);   
   output_a(0x02);
 
     
   ext_int_edge(L_TO_H);
   
   enable_interrupts(int_ext);
   enable_interrupts(GLOBAL);
}

Hi greetings! I don't know why, how on PORTB RB2-RB3-RB5-RB6 were being logic "1". I just wonder why this happened ?
If someone could explain, thanks respects!
PCM programmer



Joined: 06 Sep 2003
Posts: 21543

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Re: PIC16F877A int_ext
PostPosted: Sat Nov 27, 2021 9:29 am     Reply with quote

Khansokhua wrote:

output_c(0x00);
output_d(0x00);
output_a(0x02);

I don't know why, how on PORTB RB2-RB3-RB5-RB6 were being logic "1".

You never initialize PortB. You only initialize ports C, D, and A.
If you want PortB to be 0x00, then add this line:
Code:
output_b(0x00);
Ttelmah



Joined: 11 Mar 2010
Posts: 17607

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PostPosted: Sat Nov 27, 2021 12:20 pm     Reply with quote

The point is you set the TRIS:

set_tris_b(0x01);

Now the register for a port defaults to '1' (data sheet), so when you set
the tris to set these bits as outputs all the bits (except B1), go high.
To set the bits to low, and leave B1 as an input - get rid of the above
TRIS instruction, then:
Code:

   output_b(0); //B0 to B7 now all 0
   output_float(PIN_B1); //B1 is now an input
Khansokhua



Joined: 06 Nov 2021
Posts: 45

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PostPosted: Mon Nov 29, 2021 4:10 am     Reply with quote

Thank you
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