led array

Community General Discussions
, ,
1

I would like to make an Led array say 5x5 or so but if a wanted to only light these lights

0 0 0 0 0

0 0 0 0 0

0 0 0 0 0

0 0 0 1 1

0 0 0 0 1

how would i Do it without doing this?

0 0 0 0 0

0 0 0 0 0

0 0 0 0 0

0 0 0 1 1

0 0 0 1 1

Are they flashing really fast of somthing similar?

(0 is of 1 is on)

Thanks for helping

2

Yup, they are flashing…
It is really that simple… The rows and colums are “flashing” on and off in a kinda wave. Each Led is clicked on during each wave but it is quick enough that your eye can’t see it --or can’t see the “change”.

3

thanks
thanks

4

I actually had this same
I actually had this same question. Lets say I wanted those 3 LEDs to stay lit for 5 seconds. How is it that that fourth LED wouldn’t be lit? If I lit up the rows and columns needed for the 3 LEDs the 4th would light because its row and column were both activated.

5

true, but not at the same

true, but not at the same moment

so only 3 will be lit

6

What do you mean not at the
What do you mean not at the same moment? If I want all 3 lights on at once wouldn’t the fourth light as well?

7

you will light one at a

you will light one at a time,

and loop quickly enough not to see it blinking

8

When the 4th column is on,
When the 4th column is on, only light the 4th row, when the 5th column is on, only light the 4th and 5th rows. So cycling through each column at greater than say 15 columns per second, only turn on selected rows at the time a given column is on. This might be just enough for persistence of vision to register the specific LEDs on.

9

I think that charlieplex

I think that charlieplex matrix is what your looking for. its a bit more complicated but allows you control of each individual LED.

Charlieplexing takes advantage of the fact that LED’s are diodes. therefor they only allow currant to pass in one direction.

Combine that with matrixing and you get individual control of each LED.

 

here is a instructables post that explains it nicely:

http://www.instructables.com/id/Charlieplexing-LEDs--The-theory/

and:

http://www.instructables.com/id/How-to-drive-a-lot-of-LEDs-from-a-few-microcontrol/

 

Dan (the 2nd?)

 

Edit: you of course cant have multiple LED’s lit at the same time so your back to “flickering”.

http://en.wikipedia.org/wiki/Charlieplexing

10

Yeah I got it now. I didn’t
Yeah I got it now. I didn’t understand that he said they would be flashing at a high rate. As long as they flash 25-30 times a second the human eye won’t see the LED as blinking. Thats why most cameras film at 30 FPS. The human eye thinks the movement is continous even though it is flashing still pictures.