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Topic: 5x7 LED Matrix Issue (Read 4614 times) previous topic - next topic

adamedelberg

like this?

Grumpy_Mike

The ULN2003 looks a lot better.
Now the matrix is not wired like the data sheet is it.
The data sheet shows pins 9, 14, 12 & 8, 1, 7, 2 all being anodes. These anodes should be connected to the arduino outputs.
The data sheet shows pins 13, 3, 4 & 11, 10, 6 as all being cathodes these should be connected to your ULN2003.

adamedelberg

Ahh i think i finally understand it all!

Thank you!

Just one last question, what is the advantage/or disadvantage of using a matrix with transistors instead of the IC?

It is so great to have such a helpful community!!
:)
thanks

Grumpy_Mike

Not much, that IC is a darlington transistor array so it already contains the base resistor you would need if you used a normal transistor. It is smaller so there is less wiring up.

CrossRoads

The LED wiring is off still.
Note that the pins are shown as going across the short length of the body. So you may want to plug the chip in across the middle divider.

I have labelled them A1-7 for the anodes,
and C1-5 for the cathodes.

A1 is pin 9
A2 pin 14
A3 pin 8
A4 pin 4 (also available on pin 12)
A5 pin 1
A6 pin 7
A7 pin 2

C1 pin 13
C2 pin 3
C3 pin 4 (also available on pin 11)
C4 pin 10
C5 pin 6

If you look on the bottom of the part you may see a 1 next to one of the corner pins.
Plug it in and drive the output pin for C1 high (display pin 13) and for R1 low (display pin 9) - should see the corner LED turn on.  If not, rotate the display 180 degrees around and try again.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

adamedelberg

there are 7 pins on each side of the LED matrix..

CrossRoads

The pin numbers I gave above correspond to those 14 pins.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

adamedelberg

I have built the circuit but the matrix is not working correctly

could you take a look and see if i have made a mistake.

(the resistors are not connected on purpose, was checking if they were limiting matrix too much. BUT are connected during tests)

The results are slightly dim LEDs slightly brighter LEDs, some off.

Grumpy_Mike

Quote
I have built the circuit but the matrix is not working correctly

We need to know exactly what it does and what you expect it to do.

CrossRoads

Pin 1 on the ULN2003 is the lower left corner?
Looks like you have 6  outputs wired up? While there are only 5 cathodes?

Same with the display - pin 1 is lower left? Any chance its just flipped?

How about posting the code you are running?
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

adamedelberg

#25
Oct 25, 2012, 07:35 pm Last Edit: Oct 25, 2012, 07:38 pm by adamedelberg Reason: 1
Code: [Select]

const int rows[] = { 9, 14, 12, 8, 1, 7, 2 };
const int cols[] = { 13, 3, 4 , 10, 6};

void setup()
{
 for (int c = 0; c < 7; c++)
 {
   pinMode(cols[c], OUTPUT);
   digitalWrite(cols[c], LOW);
 }

 for (int r = 0; r < 5; r++)
 {
   pinMode(rows[r], OUTPUT);
   digitalWrite(rows[r], LOW);
 }
void loop(){
}


CrossRoads

LIttle light on the application code here 8)
Code: [Select]

void loop(){
}
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

adamedelberg

Just really want to get it working first ;P

adamedelberg

when i execute that code, this is the result:

Grumpy_Mike

Quote
We need to know exactly what it does and what you expect it to do.

I would expect from that code that all the LEDs should be off. What do you expect?

As all the LEDs are not off then you have wired it up incorrectly.

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