Solderless LED Matrix?

Great Video, Pedro,. I see you are having fun and getting really valuable experience. Keep it up.
@ CR Those Pololu links were great. Good prices on good jumpers... 22 Ga. Too. Most of those jumpers with the round ends are 30 Ga wire... Caused me a lot of grief before I learned. $10 for 50 pieces is a good price because those last forever.

Bob

Thanks for the encouragement Docedison.

Yes as you may have noticed I am finding the coding side of things a steep learning curve whereas some beginners on the forum seem to pick it up rather quickly :grin: Oh well I will keep plodding along and yes I am having fun and that's the main thing,

Pedro.

Yup, I get a lot of use out of the pololu.com wires & headers & stuff.

I guess the reason I just want to control individuals LEDs is that I don't have the wires, etc. yet to make my matrix, but I do have enough to plug in 8 LEDs and start experimenting with them. I'm hoping to be able to learn about the Max this way as I wait for the other parts to arrive.

Can someone help me understand how the matrix works? I've wired up a 3x3 matrix as in the attached image (no Max chip at this point). My understanding is that if I apply 3.3 volts to row C and make column 1 ground, the electricity should flow through the bottom-left LED (as in the top-right of the image), turning it on. What seems to be happening, though, is that the electricity bypasses the LED and flows directly to the ground, meaning no LEDs light up (as in the bottom part of the image). This makes sense to me since electricity usually follows the path of least resistance. But everything I am reading online seems to indicate that what I am trying should light up the LED. What am I missing here? Can anyone help me out?

I should also note that I have a 100 ohm resistor at the beginning of each row.

If you measure from C to 1, do you measure a short?

Pedro,

I love your 8 x 8...

could you attach your code for that please.....that was pretty cool

That is a ridiculous price for the MAX7219. Well, the normal price is the ridiculous one...but $1.25 is unheard of. Somehow I think that can't last long.

FYI, I bought some from Ebay...10 for 4.99 $ 2 weeks waiting time but oh well

http://www.ebay.com/itm/130733916831?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

Yes, still $1.25 for MAX7219 DIPs. Just ordered 12 more, $1.80 for shipping.

I'm patient though...I can wait a few weeks because I have LED flex strips as well coming....another Nano coming as well......lots of projects.....

I'm going to shorten another enclosure down to just two matrices and make sure I get it scrolling how I would like too....

I have 1 max7219 left...10 on the way....

I'm looking into maybe getting some larger matrices too, maybe some RGB's

Aaron, glad you like my 8 x 8 displays. When I get home from work I will post the code. Good luck with your 8 x 32 enclosure, I am also working on one. The Max 7219 chips are very popular on the forum lately aren't they.

CrossRoads:
If you measure from C to 1, do you measure a short?

How would I go about testing this? If I do measure a short, what problem might this indicate?

Use a digital voltmeter.
If it measures shorted, you need to find & remove the short.

Pedro, you can click Additional Options below and attach it right here, no need for outside links.

Thanks for that Crossroads

Aaron, here is the code for the 8 x 8 display patterns in reply 13

Pedro.

Compilation_Of_All_Mk1.ino (30.1 KB)

Sweet! Thanks Pedro. Oh and while I have you ans crossroads, my 8 x 32 is ......75% working......at first I had letters backwards and was looking at the code for the problem, but then I woke up and realized my column pin outs were swapped.....so the matrices are good on correct letters now, its just my code somehow makes all 4 say the same letter from my string as they each scroll.....I want them to scroll across one another......still WIP

I did play around with two matrices and LedControl and had this problem too. From memory (not stating fact) I had the number of devices integar set at 1 instead of 2

LedControl lc=LedControl(12,11,10,1); 12, 11 and 10 Arduino pins 1 number of Max7219.

It maybe worth checking good luck Pedro.

So it turns out my issue was that I was connecting my columns and rows together - d'oh! Its working great now, just waiting for a few more wires to arrive and I am planning on building this before Christmas: http://www.instructables.com/id/Yet-Another-Daft-Punk-Coffee-TableDisplay/

Good catch.