Solderless LED Matrix?

To the US, shipping has been cheap. Last set of parts I ordered was $1.87 for 8 MAX7219s, resistors, and I think aset of one other small thing.
Time before that I bought a bunch of bulky electromechanical parts - pots, knobs, switches, whole mess of SMD stuff. Biggish padded envelope, $8 something for shipping. Stuff has been arriving from a Colorado address and Thailand, must be some kind of distributor deal set up?

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.

Thanks for all the help so far. I ordered a bunch of stuff from Tayda Electronics - great prices. It has arrived, but I ordered some wires from another supplier and they aren't here yet so I can't build it yet. In the meantime I'd like to learn how to use the MAX7219. All the tutorials seem to be about matrixes, but I'd like to start by just controlling individual LEDs as I assume that would be more basic and give me a better understanding of how it works. Any suggestions on good resources for this?

Hello dtaylorl,

I am hardly one to give advice with all the questions I ask on the forum 8) but I have been playing around with the Max 7219 and an 8 x 8 LED matrix and believe me by using the "LedControl.h" library they are very easy to use. Even if you did hook up one LED to the chip what could you do with it, only turn it on and off whereas with a simple 8 x 8 matrix you can turn on whole or part rows or columns, individual LED's and come up with interesting pattern displays etc. These links will get you up and going

http://arduino.cc/playground/Main/LedControl

http://www.arduino.cc/playground/Main/MAX72XXHardware

http://arduino.cc/playground/Main/LedControlDemos
As I have said I am a rank amatuer at Arduino and by using the Max chip I have amused myself for hours,
Pedro.

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