nid help on LED blinking

oo ok i get wat u mean! kk thx veri much

oo ok i get wat u mean! kk thx veri much

i try using for loop for delay, but it still cant work.

But if you had followed my advice and used the little search field in the upper right corner of this page, you would have known that you should not use a for loop to count time.

And you would also have found code that did implement delays without using a dumb for loop.

  unsigned char j;                    /* LED var */

.
.
.

    for (j=0x01; j< 0x80; j<<=1)
    {
      .
      .
      .
    }

Because j is an unsigned char, the test for j<0x80 will always be true and you will never exit the loop.

Pass#1 j = 0x01
Pass#2 j = 0x02
Pass#3 j = 0x04
Pass#4 j = 0x08
Pass#5 j = 0x10
Pass#6 j = 0x20
Pass#7 j = 0x40
Pass#8 j = 0x80
Pass#9 j = 0x00
...
Pass#n j = 0x00

Whoops - Sorry - My mistake, I didn't read the code closely enough

is there any wrong with this code?

/* BLINKY.C - LED Flasher for the Keil MCBx51 Evaluation Board with 80C51 device*/

#include <REG8252.H>


// When you have enabled the option Stop Program Execution with Serial
// Interrupt, the Monitor-51 uses the serial interrupt of the UART.
// It is therefore required to reserve the memory locations for the interrupt
// vector.  You can do this by adding one of the following code lines:

 //char code reserve [3] _at_ 0x23;   // when using on-chip UART for communication
//char code reserve [3] _at_  0x3;   // when using off-chip UART for communication


void wait (void)  {                   /* wait function */
#define TF0_VECTOR 1

int R7=20;
TR0=0;
TF0=0;

TMOD=TMOD | 0xF0; //Timer 0,16 bit Timer
TMOD=TMOD & 0x01;

TL0=0xAF; //Timer 0, set 1 second
TH0=0x3C;
TR0=1; //start timer

while(R7!=0)
{
if(TF0!=0) //test if the timer overflow
{
TR0=0; //stop timer
TF0=0; //clear the overflow flag
R7--;
TR0=1;
}
}
                             /* only to delay for LED flashes */
}

void main (void)  {
  unsigned int i;                     /* Delay var */
  unsigned char j;                    /* LED var */

  while (1) {                         /* Loop forever */
   for (j=0x01; j< 0x80; j<<=1)  {   /* Blink LED 0, 1, 2, 3, 4, 5, 6 */

          P1 = j;
                    /* Output to LED Port */
      for (i = 0; i < 10; i++)  {  /* Delay for 10000 Counts */
       wait ();                       /* call wait function */
      }
    }

    for (j=0x80; j> 0x01; j>>=1)  {   /* Blink LED 6, 5, 4, 3, 2, 1 */
      P1 = j;
                                /* Output to LED Port */
      for (i = 0; i < 10; i++)  {  /* Delay for 10000 Counts */
       wait ();                       /* call wait function */
      }
    }
  }

}