Introduction: Hunger Games - Global Warming - Neopixel Fire Thermometer Scarf
Girl on fire, well, scarf of fire…
Make this wearable as tribute to the career maker from District Philly, the Leslie Birchniss Evergreen. Use this scarf with embedded electronics to precisely sense the current temperature and humidity. What’s up with the weather? It’s hot and it’s cold. Note and use your findings to determine environmental change over time.
Look here for the original Neopixel Giant Thermometer Scarf wearable for classic style and utility.
Step 1: We Didn't Start the Fire...
I’ve seen a lot of Arduino projects that display text so I wanted to experiment with LED matrices. Premade LED matrices are somewhat expensive but I had some Neopixel LED strips that I could cut up and reconfigure into my own flexible Neopixel matrix. Actually, a whole bunch of remnants from previous projects. Don't be afraid to dice and splice your Neopixel strips.
One of the more interesting things to do with Neopixels is to make it simulate fire effects. This has been done with using the FastLED library driving WS28xx LEDs. I used the FastLED Fire example to drive the top portion of the scarf. They have a lot more examples of light effects that I will probably try later on.
Depending on how you wire up your long strands of Neopixels, since I used 4 strands of 30 and did not hardwire them as a 4x30 matrix, I minimized the use of data pins to drive two outputs - two strips in each pair will light up in sync. Alternatively, you could use one data pin by hardwiring it as a 4x30 matrix and do the Neopixel position re-mapping with code. Soldering your own wire connections will inevitably cause you to excise some bad pixels so you will still end up with a slightly varying number of Neopixels amongst the strips. That's ok because it will add to the random look when you mount them together slightly shifted to further soften the "edges of the flame." You also want to diffuse them with a thin layer of fiberfill to hide the individual Neopixel LED dots.
As with the original thermometer scarf, I’ve since gotten a better DHT22 temperature humidity sensor (wider range than the DHT11) because people polar bears were commenting, wait, laughing at the subtropical temperatures we enjoy indoors and have even dared us to venture outside of our parent’s basement. The DHT11 and DHT22 are capable of sensing humidity so I am able to display that also.
A better way to display those readings is by printing the digital readout instead of visualizing it on a traditional thermometer scale. After all, no one knows how to read an analog clock face any more... The Adafruit Neomatrix and GFX libraries make it easy to display text on any Neopixel matrix. With the actual small matrix size of 8x8, we make it scroll text displayed with an 8x5 font. (I cut out strips to make it 8x9 but had to sacrifice a row to troubleshoot wiring issues.)
It was my first foray in using the FastLED library but I haven't figured out how to use that for scrolling text on a matrix. I didn't find a sample code to decipher. I ended up utilizing the Adafruit GFX and Neomatrix libraries learning from the scrolling text code in the Adafruit SMS Messenger bag tutorial. I was able to load the different libraries together in the sketch and run them without any conflicts. The flame animation is slowed down a bit because of the scrolling text operation but I think code can be reworked to use one Neopixel library for optimization and better speed.
So what did I find out? Troubleshooting Neopixel strips that you wire up yourself can be maddening. I think I toasted my 2 Adafruit Floras because wonky wiring may have caused excessive current drain. I had to dust off my old Arduino UNO to use. I had the test sketch initially set at full brightness so I learned later to set it lower. The addition of my Neopixel 8x8 matrix to the circuitry also did something strange to cause the UNO to drop its serial connection. It may have tripped the fuse on the USB port. I wired up the connections to the board with header pins so that I can pull out and remove when trying to program the board. I think I was able to lower the brightness levels enough so that I can keep everything plugged in and retain the serial connection. Maybe I should not have tapped power directly from Vbatt on the board.
Mount all the electronics on a layer of fabric so that you can just stuff the module inside the scarf. You can add some sheet fiberfill batting or a layer of fabric to diffuse the lights. I used two layers of microfleece fabric to diffuse the lights. There is a sewn in pocket on the back to hold the Arduino and battery pack.
Step 2: Who's Your Stylist?
I found some interesting fabrics at the discount fabric store. One was all swirly, pouffy and reminiscent of the couture Wedding Dress in Hunger Games - Catching Fire. It has these fabric "flowers" or rosettes sewn on the surface to give it a 3D texture.
The other was a black charcoal sparkly sheer fabric that would be perfect for the bottom portion of the scarf.
Scarf construction is pretty simple. It is basically made from two long pieces of material cut 6 feet by about 7-8 inches wide sewn into a fabric tube. You don't have to be too exact and measure but that gives you some seam allowance to sew the perimeter. A serger is a great tool to have to quickly bind and trim long straight edge seams.
Mock up the layout of the electronics to see where everything will go and what you need to fit. You can determine where you should transition the two different fabrics - dark bottom to light top. You can make it easy on yourself to include in an access hole in the middle of the long scarf to reach in and position or secure the electronics layer.
Attach the light and dark fabric pieces together. Place the front and back pieces together with the good faces on the inside.
Seam the two sides. You can leave the top end open if your fabric has finished edges. Leave the bottom open to stuff in the electronics. You can seal that up when you finish. Turn the assembly inside out so you have a nice fabric tube with clean edges.
You can then stuff in the electronics inner layer, secure and close up the scarf.
Step 3: Embellishment...
We know what we're doing here. Ok, we really don't but follow along.
Make the Mockingjay latticework trim piece. I guess you could 3D print something like that but it might take several hours to design and print. I just laid out a small wireframe of wire pipe cleaners and stiffened up the structure by coating in glue. When dry, paint it silver or do something glittery. I couldn't tell from pictures if that was supposed to be a molten metal design with jewels or just slag bubbles in the pour. I dotted the piece with silver 3D fabric paint to add that texture. Attach to the scarf with a few stitches, tie-wrap or safety pin on.
And throw in a 3D printed Mockingjay pin as an accessory. You can find some designs on Thingiverse. I printed one out and stuck on a pinback jewelry finding to make it a brooch. I don't have true goldfil 3D printer filament so I had to paint it with acrylic metallic gold.
Add on GPS, datalogging and IoT/Wifi/Bluetooth capabiity to offload the data and we're done.
And there you go, may the odds ever be in your favor.
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