getting problem on hardware

[internetuser2k13]

am working with 18f452 and i wrie this code

#include<htc.h>


// PIC 18F452 fuse configuration:
// Config word 1 (Oscillator configuration)
// 40Mhz crystal input
__CONFIG(1, OSCSDIS & HSPLL);
// Config word 2
__CONFIG(2, BORDIS & PWRTDIS & WDTDIS);
// Config word 3
__CONFIG(3, CCP2RC1);
// Config word 4
__CONFIG(4, LVPDIS & STVREN);
// Config word 5, 6 and 7 (protection configuration)
__CONFIG(5, UNPROTECT);
__CONFIG(6, WRTEN);
__CONFIG(7, TRU);

#define _XTAL_FREQ 40000000   //MHz



void delay_sec(unsigned char seconds)    // This function provides delay in terms of seconds
{
    unsigned char i,j;

    for(i=0;i<seconds;i++)
    {
       for(j=0;j<100;j++)
        __delay_ms(10);
    }     
}

void main()
{
      
    TRISB = 0;   
    while(1)
    {
        LATB = 0xFF;   // ->  0101 0101
        delay_sec(1);   // delay of one second
        LATB = 0x00;    // ->  1010 1010   
        delay_sec(1);    // delay of one second
    }
}

first am not getting output exactly for which i wrote this code.
when i burn this code and supply power , then i get the portB all pins were active but its not going to zero ..
but after some time when i remove power and again connect the voltage then its blink but not for 1 sec. its about 4 sec. and some time it take 1sec, some time 2 sec.
but when i try any other data like

LATB=0x55;
LATB=0xAA;

or any other except LATB 0x00;
its work fine with exactly the same delay.

please guide me

 

[milan.rajik]

What is the crystal you are using ? 4 MHz ?

 

[horace1]

am working with 18f452
but when i try any other data like

LATB=0x55;
LATB=0xAA;

or any other except LATB 0x00;
its work fine with exactly the same delay.

please guide me

if it works with half the LEDs operating but not when all are on it could be your power supply does not have sufficent current to supply all LEDs being ON causing the output voltage to drop
try changing the power supply for one with a higher current rating

 

[internetuser2k13]

if it works with half the LEDs operating but not when all are on it could be your power supply does not have sufficent current to supply all LEDs being ON causing the output voltage to drop
try changing the power supply for one with a higher current rating

i try this with increasing voltage but didnt work for me

 

[horace1]

i try this with increasing voltage but didnt work for me

increasing the voltage probably won't help -it is how much current it can can supply that may be the problem

 

[Dinuwilson]

Did you check the data sheet? any internal pull up's are there at PORTB