Well it's complex to me at least since I haven't worked much with LEDs up until now.
So, I'm starting this project soon involving LEDs and I'm not sure how to proceed hardware-ally (yep, just made that up) so I'd really appreciate some help. The project is building the Guy-Manuel helmet from Daft Punk, and the functionality of the LEDs involved can be seen here: Volpin Props - YouTube
There are four LEDs behind each of the big colored tiles, but the all the LEDs in each row are always lit or turned off at the same time so they function basically like a 8x1 matrix:
There are three rows of three LEDs, but the LEDs in each row are always lit or turned off at the same time so they function basically like a 3x1 matrix:
111 000 000
000 111 000
000 000 111
Not seen in the video (unfinished ear area) is a 1x3 matrix:
000 100 010 001 000
Not seen in video are two LEDs beneath ear area that are always lit when the helmet is "on".
So, not only is it kind of complicated (to me:)), but I also need to mirror it since the helmet has the LEDs on both sides. I'm thinking that for example, row 1 in 1) on each side could be hooked up to the same led driver or shift register (or what ever is used, I haven't quite grasped how these things work) since they are always going to be on or off at the same time. But then I don't know what to do so the brightness of the LEDs in the row aren't affected.
Circuits and Electronics have never been my strong suit but since getting introduced to Arduino last semester in a Mechatronics class at Uni (I'm studying Industrial Engineering) I want to learn more, and what better way that to take on a project I really want to finish?
So any and all help with picking out the correct stuff and connecting correctly will be greatly appreciated!
Circuits and Electronics have never been my strong suit but since getting introduced to Arduino last semester in a Mechatronics class at Uni (I'm studying Industrial Engineering) I want to learn more, and what better way that to take on a project I really want to finish?
The important thing to understand when starting to wire up led projects is about fundemental electronics, ohms law, how to calculate current flow in basic dc circuits.
As long as you use properly sized series current limiting resistors with leds you will not damage anything. If not you can easily damage arduino output pins and/or the leds. Lots of drawing examples if you search them out.
I realize there is a lot of material out there on LED matrices and stuff, but I don't know what I should do since I'm running so many simultaneously, and that's why I need help
hmm, maybe I could make the whole 1) on both sides as an 8x8 matrix, but it seems so pointless to be able to control each and every LED as the rows are always going to be on or off at the same time, instead of just rigging one row of eight LEDs as "one LED" and just having an 8x1 matrix.
I just don't know enough to pull that off, so help would be appreciated
If could make each row in 1) function as one LED, and do the same to the columns in 2) I could merge that into a sort of 8x2 matrix, and then do the same to the rows in 3) so that six LEDs in a row would function as one, and then merge put the row in 4) into that matrix.
I don't actually know if this stuff is possible, maybe just connecting the rows of LEDs in parallel is enough and then connect as a regular matrix? I'm just thinking out loud here, hoping someone can help me, but if this way is possible I'll have two matrices, a virtual 8x2 matrix and a virtual 3x2 matrix... Hmmm maybe I can then join them together and have a 11x2 matrix? Is that possible?
Gonna try to throw up a diagram in paint to explain what I mean
This has been done or attempted a few times here. It is a difficult project not because of any complexity but the mechanical construction is hard for a beginner. You need to consider the batty requirements wand look up series and parallel connections of LEDs.
I would start small and work your way up.
Yeah I've begun doing some small calculations and looking into parallel LED circuits, gonna go to the electrics store tomorrow and buy some stuff for running tests, as right now I don't really own anything for this project except the Arduino board since I'll be buying it next month when I go abroad (this kind of stuff here in iceland is expensive and sometimes hard to come by)
According to LED Resistor Calculator with my white LED which apparently has a voltage drop across it of about 3.5V and a desired 20 mA of current I should use a 10 ohm resistor for 8 LEDs in parallel.
After my tests I'm going to do some more research on LED matrices to make sure I can actually do it like this.
EDIT: After reading about the MAX7219 chip that looks like a very easy and comfortable way to go... Will keep reading alot though before a decision is made
I'm leaning towards using a couple of MAX7219 LED drivers since I have to use a LED driver anyhow (or shift register, which I know nothing about), each one of those can control 64 leds, and as I'm using 130 LEDs it seems like a good idea to use one MAX7219 for the 64 LEDs behind the colored tiles, and then the other MAX7219 for the rest minus 2, but since the MAX7219 only uses 3 digital outputs I can hook the other up right to the Arduino.
So now my biggest problem is indeed powering this whole thing... I was thinking about using 8 1.2V rechargable AA batteries connected to the vin plug on the Arduino, but I don't know if that is ideal... I've been reading up on similar projects but haven't really found anything I could "copy" to my project, any advice?
I'd ideally want to be able to run the lightshow on this thing for a few hours at a time, but it wouldn't be a big problem having to change the batteries every 2-3 hours (I'm probably dreaming, right? ::))
Folks are tryin to tell ya is ya dont have that many lights.
(1) 8 tiles = 8 lights
(2) 8 columns = 8 lights
(3) 3 rows = 3 lights
(4) 3 LEDs = 3 lights
(5) these dont need to be controlled.
So first change your thinkin to Arduino only need to control 22 lights. We assume L and R sides do the same thing.
Some of the lights contain more LEDs than others, thats a separate matter of driving sufficient voltage and current for the series / parallel arrangement you choose.
Example: suppose you chose 8x1.2V battery for 9.6 v total. You said LEDs are 3.5 v each so you can combine them in pairs in series to drop 7v and your resistor only drops (wastes) 2.6V. The calc say you need 130 ohms for 20 mA. Now you need 4 of these pairs to make 2 tiles = 80 mA. Driving 2 tiles with 1 transistor is easy.
Do this for the other lights. Add up current for all the lights that are on at same time (typically) and divide the total (plus some for Arduino) into the battery capacity to see how long a charge will last.
This is what I'm so bad at, drawing up circuit diagrams and calculating. I am ofcourse familiar with Ohms law and all that stuff, but when it's comes to more complicated wiring and problem solving in electronics I'm kind of lost. I don't even properly know how a transistor works (although I do know they are used to amplify a signal), which is the reason why I avoided using them on my project in class (which was probably a mistake).
So there are a few things I'm not clear on, doesn't the Arduino board give out 5V? How would I hook up "22" lights to the arduino since there are only 13 digital outputs without using a LED driver? I really wish I had put in more work during that electronics class