i got everything all wired up, and found some test code online that i modified to work on my 5x5x5 cube. it displays test patterns fine, but text is not quite working out for me.
i got the cube wired directly to an arduino mega (pins 26-50 are anode columns, 2-6 are cathode layers). first of all, am i going to kill anything running like this? should i put resistors on anywhere?
anyway, back to the main problem i'm having. i went and modified the code to activate the columns i need to make text, A-Z. if i have just one letter set to display, it works pretty good (the other LED's on the layer are on, but barely noticable). if i set it to display one letter then another, it looks nothing like a letter, more like just a blob.
as i have said, i am a total NOOB. i have had the arduino for about a week, and have played with it a little. i have never in my life written code. i can post the mess i have now if anyone's interested, but try not to be too harsh on me LOL.
i can also post pics of the cube---at least that came out pretty nice
am i going to kill anything running like this? should i put resistors on anywhere?
Without resistors or some other form of current limiting there is a very big risk of damaging the Mega's I/O pins. There is sure to be published 'led cube' circuits available that show how they handled interfacing to the LEDs.
......i have taken the code off my isp's server---they're a bitchy bunch LOL. if need be, i will repost.
also, i have had some luck with other code i found for a 3x3x3 and modified it for my 5x5x5. got most of the text working and looking good. i might get a youtube account and post it with the eight million others LOL.
.......i know i'm beating a dead horse with the cube, but i still think they're pretty fun to mess around with.
Udo, the code i have is pretty long. i can email it to you if you want to PM me.
pluggy---it has been running 24/7 for 4 days straight with a simple test pattern and some text. i was actually just frustrated and got it working, so i left it on to see if it would fry it LOL. it's still running good.
it has been running 24/7 for 4 days straight with a simple test pattern and some text. i was actually just frustrated and got it working, so i left it on to see if it would fry it LOL. it's still running good.
No offence meant, but you have been advised by more then one poster that current limiting (by resistors or other means) is a requirement when driving LEDs. However because you have it working without, you seem to just dismiss or ignore that advice. To ask for advice but then ignore it can on first impression be a little frustrating, at least for me.
We are not trying to sell you resistors, or otherwise make your project more complex then it needs to be. It's your controller board and you have every right to treat it as you wish. I just question if you realize the risk to your investment you are taking?
To jump on with Retro here..
You've got to keep in mind.. when you're running a cube like this.. you can be outputting as much as 80 ma (guesstimate, depends on size of the LEDs) and even more.. which will fry your outputs. The MAX suggested per pin is 40 ma.
Now, if you have transistors on the bottom.. you may be okay, but you still risk frying some LED's. (Keep in mind... frying includes, burning out over time) Just because it works without resistors, doesn't mean it will work for long! If you limit everything to the correct current, and voltage, your LED's will go on to live a much longer, happier life!
Hopefully Grumpy_Mike can come in and do some calculations for how much current you can draw at any one time from this setup. (Or anyone else who has a better understanding of Ohms Law! I'm decent with math.. just still don't understand how to convert mA and resistance and such, to a voltage.. just the moving the decimal points over is what's confusing me the most!)
Well, ohm's law is not everything here. The actual issue is not current but heat. That is depending on the duty cycle more current can be acceptable. Actually it is even a little bit more complicated. In order to protect the outputs I would add 100 ohm in series with each output.
If this makes the LEDs to dim I would add transistors for switching them. Still at least 100 ohm in series with each output, maybe even more depending on the transistors. If FETs or IGBTs are used, the resistors can be left away.
If you go for transistors add resistors (again 100 ohm recommended) for the LEDs. You do not want to burn out the LEDs as well.
sorry if i offended anyone---i did not dismiss the advice of the members here. i am waiting for the 100 ohm resistors to arrive in the mail---they're just taking a while. i'm also awaiting 150 ohm resistors and red led's (the wife likes red LOL).
i do sincerely appreciate any and all help offered. i will post updated pics as i progress.
well, i've been busy at work so not too much time to play. i did get some more parts to make the cube NOT kill my mega. i have the anodes running off some CD74ACT541E chips, and the cathodes running off a 7407 hex buffer. i also have the correct resistors installed to protect everything. here's a pic of it in the chip testing phase, which was this morning. i will mount everything on a board some day
i am working on a 7x7x7 now. i have it all wired up and mounted in a 3/8" thick Lexan box i built from some "scraps" at work LOL. here's a pic of that, so far. don't mind the wood under it--that's just my jig.
