Arduino LED Sword Project Planning

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flippinpony
 
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Arduino LED Sword Project Planning

Post by flippinpony »

Hey all,

I'm in the planning phase for a pair of Arduino-powered LED swords and was hoping to get some advice and ideas before I go forward. I've taken on a few Arduino projects in the past (including an animated LED tron disc), but this project is looking to be a bit more complex.

Goals:
-Two swords with 1 meter plexiglass blades and plastic hilts
-64 LEDs in the blade of each sword (two 1M strips, back to back)
-Arduino and battery in hilt of each sword
-Android app sends animations to the two swords via Bluetooth, allowing synched LED animations

Questions:
-Adafruit has a few Arduino Bluetooth modules, which would be best for my purposes? I need to be able to connect to 2 simultaneously.
-Would an Arduino Micro work for my purposes? The digital RGB LED addressable strip on Adafruit only needs 2 pins to send data, but the Bluetooth module may require quite a few.
-Any battery suggestions? I'd prefer to run one 5V battery to power the Arduino and LED strip, and want the battery to at least last a few hours.

Thanks in advance for the advice, and feel free to add in any other comments or hurdles I may run in to.

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michaelmeissner
 
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Re: Arduino LED Sword Project Planning

Post by michaelmeissner »

I believe bluetooth on Arduino is a 1-1 protocol, which would mean your Android app would have to open up two separate bluetooth connections, and do writes in parallel. According to wikipedia (http://en.wikipedia.org/wiki/Bluetooth) there are ways to do multi-cast and multiple slaves, but whether you can do it in both the Android system and the simpler bluetooth devices on Arduino, I don't know.

I would also be skeptical that you could use bluetooth to do real-time animations. Depending on what you are doing with the animations, it may be simpler to just have several canned animations, and use bluetooth or other radios just send a simple command to say start sequence #1, etc.

Note, distance may be an issue as well.

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flippinpony
 
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Re: Arduino LED Sword Project Planning

Post by flippinpony »

I would also be skeptical that you could use bluetooth to do real-time animations. Depending on what you are doing with the animations, it may be simpler to just have several canned animations, and use bluetooth or other radios just send a simple command to say start sequence #1, etc.

I was leaning towards doing most of the animation programming on the Arduino, so the app would most likely have you select an animation and maybe modify some parameters (speed, colors, etc) and then send a single message to the Arduino which it can interpret and build the animation on that end. The more important thing is that the two Arduinos can be synced up.

Opening 2 Bluetooth connections sounds okay, though that's the one area of this project that I don't have any experience with. I'm sure I'll run in to some weird quirks.

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wdickenson
 
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Re: Arduino LED Sword Project Planning

Post by wdickenson »

So I will start with - when you get this done... send us the link because I have always wanted to do this ..

1 meter is long for plexiglass. It' not overly good at flexing and bending without cracking and as strange as it sounds, it's a tad heavy. Best intentions (oh I won't hit it ) don't work in the heat of battle. If you know someone with a 3D printer, you might want to consider a 3 piece blade.

I can't speak to bluetooth LE but the Simple RF M4 Receiver - 315MHz Momentary Type worked well on my pond lights. I send commands to them all from one UNO in the house. . You can put an UNO in your pocket and send commands to the two swords. Again, bluetooth might be fine but these might be easier.

Any decent LiPo battery should do it for more than a few hours. Get two for each sword so you can swap out. But keep them low in the handle. They don't like bashing much. again, my pond lights go for 3 days with no sun.

are you going to add an accelerometer and change the display when they connect ?

sounds like fun

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flippinpony
 
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Re: Arduino LED Sword Project Planning

Post by flippinpony »

I'll probably make them play some sort of animation when they connect, but I was going to avoid throwing in an accelerometer. I don't really want them swinging around too much, unless I end up going with a sturdier material. It'd be a bit simpler using an uno to control it, but I wouldn't know how to make a good interface for controlling them and doing different things. A benefit of using an Android app is that I should be able to use the mic to do some cool sound reactive stuff (though I could do the same for an Arduino remote as well, I suppose).

All of the LiPo batteries I'm finding are 3.7V, would I need to step that up to 5? I'm trying to keep the circuit as simple as possible.

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michaelmeissner
 
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Re: Arduino LED Sword Project Planning

Post by michaelmeissner »

Yes, li-po's are 3.7v (or 5.6/11.1v for paired li-pos). Early neopixels were more tolerant of 3.7v, newer ones seem to not be as tolerant. You could either step-up the voltage (Adafruit sells Power Boost 500 and Minty Boost) from a li-po, or use a battery made for re-charging cell phones which provide 5v power. You can get cell phone chargers for about $10 or so. The big issue with lights is how longer your battery lasts. I find neopixels to be extremely bright, so I tend to not go beyond a power level of about 30 for goggles.

The only timing test I've done is a Gemma could power a pair of 16 LED neopixel rings (i.e. my steampunk goggles) for at least 24 hours with the Adafruit 1200maH lipo battery. The battery had been discharged when I next checked on the goggles 36 hours after I started them.

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michaelmeissner
 
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Re: Arduino LED Sword Project Planning

Post by michaelmeissner »

In terms of processor and voltage, you want to use a 5v processor to avoid having to use level converters with the newest neopixels. The Arduino Micro looks reasonable. My favorite board is the Teensy 3.x, which is 3.3v, and for some neopixels, I need to do level conversions.

However, if you want simplicity, I would look at the pololu.com A-Star 32U4 mini LV, which was recently announced. It has the same chipset as the Arduino Micro (and the Leonardo), but it includes a built-in step-up/step-down voltage converter that takes 2.7-11.8v of power and converts it to 5v (up to 1a, depending on the power of the battery). Since the chip runs at 5v, you don't have to do level conversions. I have one on order, to simplify neopixel setups.

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flippinpony
 
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Re: Arduino LED Sword Project Planning

Post by flippinpony »

That sounds really neat, though I don't know if 1A would be enough for my purposes. I'm seeing a max draw of 2A per meter, so I was going to power the pixels directly from my battery. Since I'm planning 1M out and 1M back, I should be able to tie my battery to both ends of the strip and avoid brownouts.

This stuff is dangerous.. now I'm having to resist the urge to spend a ton of money and cover everything I own in LEDs.

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wdickenson
 
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Re: Arduino LED Sword Project Planning

Post by wdickenson »

A lot of duration is color and brightness. I don't do much in the 255 range. Most of my colors are down around 120. That said. I am running 32 on a trinket 5v.

If you are comfortable with the android then have fun !

And I suppose you already rejected IR for this ? Outdoor ?

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adafruit_support_mike
 
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Re: Arduino LED Sword Project Planning

Post by adafruit_support_mike »

For portable electronics, the best place to start is the power supply.. those tend to be the least flexible constraints.

Each NeoPixel contains 3 LEDs, each of which consumes 20mA. 64 of them will have a peak current consumption of about 4A. That corresponds to full-on white output, which is rarely used. Our rule of thumb is that you can make most projects work on 1/4 to 1/3 of the peak value without too much effort.

That still means you'll need about 1000mAh @ 5v per hour of runtime. Getting several hours of continous use will require a fairly large battery pack. You can trim that down by reducing the on-time or the number of LEDs active at any given time, but those decisions will have a major effect on your plans for usage.

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