Limelight: DIY Lime-Shaped Presentation Timer With LED Segments

By Mallika Rao & Josh Kotel

For our final design, we were between several ideas. Our pomodoro timer was the frontrunner but we became apprehensive about the lack of time and level of design we wanted to achieve.

We also strongly felt we wanted to design devices that worked as a set–either for communication or otherwise–but offered a shared experience.

Sticking with the Pomodoro clock here, the idea would be that there are two halves of a tomato, that share a countdown between teammates or friends. The seeds would be cutout of the opaque face of the sectioned tomato, illuminated by yellow LEDs behind it. We like this idea, but as we explored it, it seemed it might be too involved for the short turnaround. Pending.

Currently we are creating “Limelight,” a lime-like timer for presenters. Limelight sits quietly at the podium with you, gently illuminating the minutes. There will be two halves to limelight, that ideally will work in tandem. (Plus it’s fun to say “Limelight is lime-like”)

We plan to use hollowed-out foam core for the body of the lime (housing the electronics), a semi-opaque plexi for the face, and potentially chipboard to sectionalize each segment. Each half will come together with tiny neodymium magnets, and we are exploring whether we will be making the timer begin at separation (if possible) or by button. For the lights we plan to use our neopixel mini button LEDs.

3D Model Iterations for the ‘Limelight’

Build

3D printed. Partially opaque face with the gemma sitting behind the sectional grooves. 1 LED per section, back-covered with opaque electrical tape.

Materials Ordered

• Gemma M0 (in PoD)
• USB-C breakout board
• TP4056 Li-poly battery charger
• 3.7V Li-poly battery
• NeoPixels buttons (in our kit)
• Hall effect sensor

Wiring

Gemma M0 w/ LED Buttons + Hall Sensor → TP4056 plugged into Battery→ Breakout Board charged via USB C with the port built into the housing

Instructables Profile

https://www.instructables.com/member/mrao9/?cb=1764774740293

Tinkercad

Arduino Code

#include <Adafruit_NeoPixel.h>

#define LED_PIN 1
#define NUM_LEDS 8

Adafruit_NeoPixel strip(NUM_LEDS, LED_PIN, NEO_GRB + NEO_KHZ800);

int currentLED = 0;
unsigned long previousMillis = 0;
const unsigned long interval = 60000;

void setup() {
  strip.begin();
  strip.setBrightness(50);
  strip.show();
  
  strip.setPixelColor(0, strip.Color(200, 255, 50));
  strip.show();
}

void loop() {
  unsigned long currentMillis = millis();
  
  if (currentMillis - previousMillis >= interval) {
    previousMillis = currentMillis;
    
    currentLED++;
    
    if (currentLED < NUM_LEDS) {
      strip.setPixelColor(currentLED, strip.Color(200, 255, 50));
      strip.show();
    }
  }
}

Learn how to make this using our instructable.

Watch our video tutorial too!

Thank you!!