Teensy\/Hardware control<\/b><\/p>\n
LEDs! I got my Teensy 3.1<\/a> board and started playing with the digital LED strips I got. I was having a heck of a time getting any sample code to work. I finally cut off the first LED and soldered the leads to the second one; then things started to work! I must have killed it accidentally; probably with reverse voltage, or other thing. As noted in Notes on v2<\/a> WS2812B LEDs would be better to use, as they have reverse protection built in.<\/p>\n What library to use?<\/b><\/p>\n I am looking at using the AdaFruit NeoPixel library, or the teensy OctoWS2811 library<\/a>. I did a rainbow pattern with each. The octo library is GOBS faster, but occasionally flickers for some reason. The adafruit one is slower, but seems more consistent. I’ll probably abstract how I use each so I could switch back and forth with a #define. The website for the Octo has great info on the LEDs though.<\/p>\n Power<\/b><\/p>\n I need a 5v power supply to test the LEDs. So, I need to figure out how much power they draw. The 59 LED strip I have draws 0.73amps at 5v, or about 0.01237amp per LED, or 12.4ma. I am looking at roughly 6m of LEds, 60LEDs per m, or: 360 LEDs per side, 720 total. I read on the Octo site that they can draw about 3 amps per 60 LED strip, so I’d be drawing up to 36 amps! I measured again at full white for my 59 LEDs, and got .87amps at most (870mA, or 14.8mA per LED)<\/p>\n spark fun say<\/a>s 60ma per LED. That would be: 60ma*720LEDs\/1000=43.2amps.<\/b> Yikes. Let’s not run them at full white! With a 2000mah Lipo battery that can do 15-20c, it could put out the 30-40amps required, but it would run for, oh, 4 minutes (2ah\/30amps = .0667 hours = 4.00 mins).<\/p>\n Pololu<\/a> says 4.7amps for 2meters of 60LED per meter. So, they calculate 28amps most for my 12meters total.<\/p>\n But my calculation on full white says: 14.8mA\/LED*720LED = 10.6A. I think I’ll plan for about 15amps max..and uh, see how it goes. I won’t be running full white continuously.<\/p>\n The problem is for my testing I don’t have any way of providing any more than 2amps at 5v (a “wall wart” power supply that I have, or making my own ~1amp DC power converter circuit on a breadboard, which overheats). So, I have to order a better power supply, just for testing (I could use LiPO batteries..but I also don’t have any!). So, I ordered a 40amp (just in case!) 5v power supply<\/a> from ebay for $30, which will come in handy in the future for other electronic projects.<\/p>\n I’m planning on using a 2cell Lipo battery for the power. I’m thinking of using two ~1.2 to 1.4ah batteries, since the runs are long (one for each half of the wheel). The LiPo battery will be 7.2v, too high for the LEDs. I need 5v. I ordered a small step-down voltage regulator<\/a> from Pololu capable of doing 7amp continuous, and 15amp max. That should meet my design requirements (unless the stupid wheel really pulls more than 20 amps). I bought two\u2026one for each battery, which might reduce the load in half. I might use one, or two; I’ll experiment on a breadboard first and measure actual power consumption. I also ordered some thermal adhesive<\/a> from amazon (free shipping with Prime..I signed up this month since I’m buying a ton of stuff, and will cancel when the trial is over). I can use this to make the regulator have a large heatsink (the wheel!) to handle closer to the 15amp limit. Or, so I hope, and that’s only if I need to.<\/p>\n How long will the 1.4ah 7.2v battery last? It has: 1.4*7.2: 10.08watt\/hours in it. The regulator is close to 95% efficient, so It’ll pass through 9.576watt\/hours. At full white, 10.6amp*5v=53watts, so, I’m looking at only a 10 minute capability at full white. One color at a time will take 1\/3 the power, so I could easily get 30 minutes with most patterns. Two batteries in parallel seem to be a must to double the amp-hours. That would give me 20 minutes of full white, and an hour run time “in general”. I just have to find some batteries that will fit in the wheel!<\/p>\n Need more LEDs<\/b><\/p>\n I realize now that I need more LEDs. I want two strips on each side. I also think I’m going to get “bare” LEDs and cover them in epoxy. So, I need to order some more. I want them to all be from the same batch..just in case there is some discrepancy. I need ~6m per wheel side, so 12m total. They are sold (usually) in 5m rolls, so I need 15m, which gives me some spares for “mess ups” (In addition to the 6m I already have, geez!)<\/p>\n WS2811\/WS2812\/WS2812B LED Sources. 60 LEDs per meter, and I need 12 meters min.<\/b><\/p>\n * AdaFruit NeoPixel<\/a>— Waterproof<\/b> (not bare, not desired), not “B” (as far as I can tell). $23.95\/meter. – $287.4 for 12 meters.<\/p>\n * SparkFun<\/a> (where I already bought some). WS2812, but not “b” (I don’t think). $20\/meter (roughly), bare<\/b>. Come in 5m reels, but also sold by the meter. $240 for 12 meters.<\/p>\n *<\/b> Pololu<\/a> – WS2812B (the only one I know for sure has the B) – waterproof<\/b>, $22.95\/m (when ordering 10+): $276 for 12m.<\/p>\n * AliExpress<\/a> – Looking into this option, as I might be able to get what I want for much cheaper.<\/p>\n http:\/\/www.aliexpress.com\/item\/Free-shipping-dc-5v-4m-240-leds-60-pixel-m-5050-smd-rgb-ws2812b-ws2811-led\/1519096378.html<\/a> – 4m\/lot, 3lots: $140 (save $100!)<\/p>\n \u2026and many others\u2026<\/p>\n EDIT: I bought these<\/a> from Ali Express.<\/p>\n Charger\/power supply<\/b><\/p>\n