5x7 led matrix disply problem??

[satyasankar09]

i am trying to display capital "H" on 5x7 led matrix using 8051...but i can see the correct output..what is the problem i cant find out...
i have attached the ckt diagram and code here....

P2 is connected with 5 columns and P3 is 7 rows...

CODE:


#include<reg51.h>
void delay1(unsigned int a)
{
unsigned int i,j;
for(i=0;i<a;i++)
for(j=0;j<120;j++);
}

int col[]={0x00,0xf7,0xf7,0xf7,0x00}; // to display "H"
void main()
{ int k;
P2=1;
while(1)
{

for(k=0;k<5;k++) // scanning column and feeding by row
{


P3=col[k]; // feeding to row

P2=(1<<k); // shifting column
delay1(1);



}
}

}

- - - Updated - - -

i think there is some problem in POV rule...can any one say me what is the POV time period rule.....

 

[ernpao]

i think there's something wrong about the loop, try "turning off" P2 first before changing P3, then after changing P3 turn on P2.

while(1)
{

for(k=0;k<5;k++) // scanning column and feeding by row
{

P2 = 0;//<<<<<<<<<<<<<<<<<<("turn off" P2)
P3=col[k]; // feeding to row<<<<(change P3)
P2=(1<<k); // shifting column<<<("turn on")
delay1(1);
}
}

or maybe you're right abt the POV rule. maybe your delay loop is still going too fast compared to the rate at which you update the rows/columns. try increasing your delay?