I cannot light up all my 64 leds on a matrix display 8x8 - arduino.

Thread Starter

safwene

Joined Sep 5, 2015
3
Hi all,
i am a newbie getting familiarized with controlling led matrix display 8x8 using two register 595(project in beginning arduino book), however i can't seem to light up the 7th column, so i removed all the wires started all over again now the 7th did light up but the 8th got angry and did not light up.
My tests :
** components on breadboard : 1 x resistor, 1 x display matrix
lighting up every led individually, 3V->resistor->columnX, rowY->ground : OK.
** components on breadboard : 1 x resistor, 1 x display matrix
all cathodes to the ground, 3V->resistor->anodeX
all columns did light up successfully : OK
** components on breadboard : 8 x resistors, 1 x display matrix
all cathodes to ground, all anodes to resistor to 5V, 8th column did not light up : KO
removed all the wires from the display anodes to the resistors, tried connecting the first wire with all the anodes, they did light up, but when i try the same with the eighth wire, every column does NOT light up, changed the wire, the resistor in vain, they all seem to be able to light up the columns except the eighth wire!! i checked the voltage and it is 2.96 which is fairly higher than the forward voltage of the led.

fritzing does not have 8x8 display, just assume it is.
my led display matrix datasheet : http://www.farnell.com/datasheets/1683560.pdf

Untitled Sketch_bb_800x545.png
 

Thread Starter

safwene

Joined Sep 5, 2015
3
found the problem, it was the wire going from the 5V to the eighth resistor.
how can i remove the thread since it is uninteresting ?
 

Thread Starter

safwene

Joined Sep 5, 2015
3
// i made this program to display 1-255 in binary representation
const byte latch = 8 ;
const byte clock = 12 ;
const byte data = 11 ;
int i = 1 ;
void setup()
{
pinMode(latch, OUTPUT);
pinMode(clock, OUTPUT);
pinMode(data, OUTPUT);
}

void loop()
{
for ( i = 0 ; i < 256 ; ++i )
{
digitalWrite(latch, LOW); // register will store the sent bits
shiftOut(data, clock, LSBFIRST, i); // send each bit to the serial input of the register where it will be stored
digitalWrite(latch, HIGH); // register will push the stored bits into the output pins at once
delay(250);
}
}

lightinp_up_columns797x716.png
 

ScottWang

Joined Aug 23, 2012
7,047
If you want then you could take some photos, do some rearrangement and post it on -- The Completed Projects Collection forum, so the members can reduplicate.
 
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