The Neo Trinkey works well as a base for a USB Kill Cord. It is small and unobtrusive. It can easily run the minimal code needed (which might also be none). It readily pops out of the USB port when pulled. And it has a convenient cut out for attaching a lanyard.

Assembling the Kill Cord is really just a matter of attaching a length of cord to the Neo Trinkey on one end and then on the other to the user (belt loop for example).

The clasp on the Adafruit Lanyard is a little too big to fit directly through the Neo Trinkey cut out. But a small key ring can be used to bridge the two together.

If you want to get really fancy, there is even a 3D printable case. For that, see this Neo Trinkey Case Guide.

Any similar idea should work as well. For example, a loop of string could be girth hitched to the Neo Trinkey cut out, etc.

Neo Trinkey Software

There generally isn't anything special needed in terms of software on the Neo Trinkey. The basic triggering mechanism is the removal of any USB device. But just so we have something known to work with, here is a simple Arduino sketch that runs a rainbow color swirl on the Neo Trinkey's NeoPixels.

Here is a pre-compiled UF2 version of the sketch. This UF2 can be downloaded and dragged to the TRINKEYBOOT folder after double pressing the reset button without needing to install the Arduino IDE:

Here is the code listing for the sketch if you want to recompile or make any changes using the Arduino IDE:

#include <Adafruit_NeoPixel.h>

Adafruit_NeoPixel strip(NUM_NEOPIXEL, PIN_NEOPIXEL);

void setup() {
  strip.begin();
  strip.show();
  strip.setBrightness(50);
}

void loop() {
  rainbow(10);
}

void rainbow(int wait) {
  for(long firstPixelHue = 0; firstPixelHue < 5*65536; firstPixelHue += 256) {
    for(int i=0; i<strip.numPixels(); i++) {
      int pixelHue = firstPixelHue + (i * 65536L / strip.numPixels());
      strip.setPixelColor(i, strip.gamma32(strip.ColorHSV(pixelHue)));
    }
    strip.show();
    delay(wait);
  }
}

This guide was first published on Jan 18, 2022. It was last updated on Jan 18, 2022.

This page (Assemble Kill Cord) was last updated on Apr 23, 2022.

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