4 x 4 LED matrix Not lighting - have pictures!

Hey guys!

My sister is trying some LED art and i would like to help her, here is my first noob question.

I followed this guide here (the arduino teacher 4x4 matrix):

http://arduinoteacher.appspot.com/matrix_9.html

And wired all my led's the same way:

|306x500

my LEDS (white 3mm 3v 20mA)

sorry for the grain factory samsung s3 mini. Sister took the camera out today.

|500x375

Only hooked one row to debug.

So after the code is uploaded successfully, i see no light change, but when i MOVE pin 9 to GND then i see the light blinking and doing what the code wants, this is obviously not cool in a matrix since i want dynamic grounds for the persistence of vision thing.

why are my digital-cathode pins not pulling to ground?

G

Reasons why you have not been answered:

  • You have not posted your code - with the code marked up in "code" tags - the little "scroll" icon.
  • The photo is useless.
  • You have not specified the resistor value - 220 ohms for a 4 by 4 matrix, 470 ohms for an 8 by 8.
  • We have no idea what "moving pin 9 to ground" means.

Paul__B: Reasons why you have not been answered:

  • You have not posted your code - with the code marked up in "code" tags - the little "scroll" icon.
  • The photo is useless.
  • You have not specified the resistor value - 220 ohms for a 4 by 4 matrix, 470 ohms for an 8 by 8.
  • We have no idea what "moving pin 9 to ground" means.

i apologise for the terrible post.

i do value the opinions and wisdom of the people here.

there was a problem with the supplied code in that tutorial. so i managed to get something working by using own code.

for some reason i think the io pins are not pulling to ground like they should,

anyway thanks for the reply. I will be more clear and friendly in my next posts

for some reason i think the io pins are not pulling to ground like they should,

That is because you are trying to sink too much current down them. With that system you can only have one anode pin high. That is the walking one not a walking zero.

Explained here:-
http://www.thebox.myzen.co.uk/Workshop/LED_Matrix.html

Grumpy_Mike:
That is because you are trying to sink too much current down them. With that system you can only have one anode pin high. That is the walking one not a walking zero.

Explained here:-
Arduino Workshop

huge thanks for this link, explains a lot. Helping me to understand sinking / sourcing /scanning.

It is not so much being "friendly", and you need not think us unfriendly in any way either, but it is the case that there must be sufficient detail of the setup and clear explanation of what does and does not happen to even begin to assess the problem.

It is a classic case of inability to mind read or as someone here often says, "sorry, my crystal ball is on the blink so you will have to show us all the details".