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LED Suit

wearable blinkenlights

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Inspiration

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Sauce: thisiswhyimbroke.com

Sauce: electricnights.net

Sauce: andivia.com.sg

$12500

$800

$300

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It’s also… not cool enough

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Feature wishlist

  • Fast (>60Hz refresh rate)
  • High resolution (~2PPI)
  • Cool visuals
  • Music reactive!
  • Battery powered
  • Controlled by phone
  • Comfortable to wear
    • Over ski gear
    • Over clothing

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Cool music reactive visuals at 60Hz?

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Milkdrop

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Milkdrop

  • Written by Ryan Geiss
  • Plugin for WinAmp
  • Looks nice, smooth, audio reactive!

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  • Unfortunately… WINDOWS ONLY!

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  • Open-source reimplementation: ProjectM

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Implementation

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Parts

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WS2812B Addressable LEDs

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WS2812B Addressable LEDs

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WS2812B Addressable LEDs

Peak bit rate: ~800Kbit/s

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WS2812B Addressable LEDs

  • (800Kbit/s) / (24 bits per pixel) / (60Hz) = 550 LEDs max strip length
  • Actually more like 300 LEDs due to reset period

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  • So… for 2000 LEDs (desired display density) → 8x parallel outputs

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System Architecture Considerations

  • LEDs
    • Raspberry Pi can’t drive the waveforms
      • Talks I2C, SPI, UART, USB and bitbanged protocols
      • SPI gives highest bandwidth for lowest engineering cost (~50Mb/s)
    • Can’t serialize all LEDs
    • Use an FPGA!
  • Audio
    • ProjectM listens to a PulseAudio source (causal)
    • Emulate Bluetooth audio sink on Pi
    • Use physical audio port to connect to external speaker
    • Physical microphones
  • Batteries
    • Peak power draw ~200W → need LiPo/LiIon
    • Want a few hours of battery life

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LED Driver

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Software Stack

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Power

  • Peak power draw ~5A per strip
  • 8 strips at 25W → 200W
  • 3x 15A buck converter (LED strips)
  • 1x 5A buck converter (Pi/FPGA)
  • 20x 3Ah 18650 LiIon cell → ~230Wh
    • 1 hour at all white, max brightness

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Batteries

  • Per-cell protection
  • Per-module protection
  • 2s2p x5

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Common terminal

BAT+

BAT-

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Power Management

  • Buck converters take 8.4V (max) LiIon voltage to 5V system power
    • Run HOT!
    • ~92% efficient
    • 8% (16W!) lost to heat (just in the buck converters)
  • Measure battery voltage/current consumption/temperature
    • Throttle LED brightness to control thermals

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Controller

FPGA (Spartan6 on MojoV3)

Raspberry Pi + 2 MIC Pi Hat from Seeed Studio

SPI

Audio Out

Strip Driver Channel

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Suit

  • Combination of nylon/polypropylene webbing and stretch webbing
  • LED strips come with silicone sheath
    • Glue to webbing? 3D print hooks?
  • Sew webbing into stretchy suit
    • Fits over different outfits
  • Aluminum enclosure for controller/batteries
  • Silicone sheathed wire (14Ga for power, 26Ga for signals)

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Demo

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Thanks!

github.com/fughilli/ledsuit