How it is possible to avoid false switching in matix display?

[padma]

hi,

I am designing 16x96 matrix display using pic micro controller ,here tlc5925 is used to drive the rows .But when i continuously enables rows and switching columns,exact character get displayed along with near by pixels .how can i avoid these false switching of pixels.can any one suggest me a better idea ,it will be more helpful for further development of my project.

Thanks.

 

[FvM]

Neighbour pixels can be dimly lit, if the multiplex frequency is rather high and the finite switching time of drivers isn't considered. You can avoid this effect, if you change the control sequence, e.g disable the column drive, change the row drive and enable the column drive again.

 

[vinodstanur]

hi,

I am designing 16x96 matrix display using pic micro controller ,here tlc5925 is used to drive the rows .But when i continuously enables rows and switching columns,exact character get displayed along with near by pixels .how can i avoid these false switching of pixels.can any one suggest me a better idea ,it will be more helpful for further development of my project.

Thanks.

when u r switching a ROW, just before that, make the LEDs OFF. Just after making ledS off AND if U r switching row then in the new row, the trace of old row values will not be seen.After switching the row, just activate the column values. {{{It happens because u r changing the row and then only changing the column values. So for a very few clock cycles ,the old column values are same for the new row!!}}}

 

[padma]

Thanks for all valid replies,in my coding i have changed the multiplexing of rows but i am not satisfied with the result.


here with I am adding my code,for(7X96) matrix display
//h/w pins
tlcoe, tlclatch,tlcinput,tlcclk,
p0,//drives each row
/*********************/

//variables
int rowselect,rowtimes,column ,temp,eight=8;
char seg1[96];//charactor buffer.


tlcoe=0;//tlc output pin enabled
rowselect=1;//rowselect variable initialized as 1
rowtimes=1;//variable specifies no.of rows
NXTROW:column =0;
tlclatch=0; // tlc latch pin
SHL1: temp = seg1[column ]&rowselect;
output_tlc(temp);//subroutine which load row data
column++;
if(column <96){goto SHL1;}
tlcoe=1; //tlc output pin disabled
p0=0; //port0 cleared
tlclatch=1; //tlc latch pin enabled to load row value
tlcoe=0; //tlc output pin enabled
p0 = rowselect;//corresponding row enabled
rowselect = rowselect<<1;
rowtimes++;

if(rowtimes<eight){goto NXTROW;}

/*************/

void output_tlc(int datain)
{

if(datain==0){tlcinput=0;}//input to tlc
else{tlcinput=1;}
tlcclk=1;tlcclk=0;//cloch to tlc

}



can any one help me to find out the mistake in my code?

 

[millwood]

i am not satisfied with the result.

because of what?

for all we know, you could just be an extremely picky person and nothing would have satisfied you.

you need help so you need to be very specific as to where exactly you want us to help you. the fact that you are unhappy with your design / code adds absolutely zero understanding and contributes nothing to solving your problem, other than adding more confusion.

 

[padma]

sir,

in my design ,i am following row multiplexing .Here initially all row and columns disabled after that column values loaded then row enabled .before enabling each row i am clearing the port(dedicated to row ).still some unwanted pixels glows .can you help me to find out where i made mistake ?is there any other way to do row multiplexing?