IO configuration and UART problem with pic16f877a

Discussion in 'The Projects Forum' started by nagesh.bsnl, Jul 1, 2012.

  1. nagesh.bsnl

    Thread Starter New Member

    Jul 1, 2012
    2
    0
    Hello guys!
    I am having a problem with pic16f77a uc. i make pin B4 as i/p and pin B5 as o/p.i give +5V(same source as given to pic and MAX232) to pin B4 so that B5 goes high and UART sends a charecter to hypertreminal. the code is :
    #if defined(__PCB__)
    #elif defined(__PCM__)
    #include <16F877A.h>
    #fuses HS,NOWDT,NOPROTECT,NOLVP
    #use delay(clock=20000000)
    #use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)
    void main()
    {
    set_tris_b(0x1f);
    while(true)
    {
    if(input(PIN_B4)==1)
    {
    output_high(PIN_B5);
    putc(0x42);
    delay_ms(200);
    }
    if(input(PIN_B4)==0)
    {
    output_low(PIN_B5);
    putc(0x44);
    delay_ms(200);
    }
    }
    }
    but whenever i connect RS232 cable, all PORTB pins goes to high and low alternatively for some period irrespective of its configuration.wat might be the problem? also is it correct way to apply +5V to input pin?i ve tried this in MICROC, Hitech C v.9.83 and facing the same problem. plz help me out, i am new to programming...
     
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