Costie

Costie is a smart LED table top coaster that reacts to changes in temperatures of objects kept on it. An easy to DIY LED coaster that costs only ₹1000 (~ $14) and offers you a variety of things. It has 3 working modes with smart object detection and recognition. When an empty glass or glass with liquid at room temperature is kept it turn on its rainbow colour mode where LEDs light up a circling rainbow pattern whereas when a hot or cold object is kept on coster it lights up in a circling red or blue pattern respectively.

Cool, isn't it?

Let's get started...!!

Step 1: Getting the Components

Hardware Parts

• 1x Custom Designed PCBs
• 1x ATMega328 (SMD)
• 1x Temperature Sensor MLX90615SSG
• 1x Battery (I used 1000 mAh LiPo)
• 1x TP4056 USB Charging Module
• 1x Wireless Charging Module with MicroUSB Connector
• 1x Reset Button
• 1x AMS1117 - 3.3V
• 1x 16MHz 3225 SMD Crystal Oscillator
• 20x WS2812 SMD LEDs
• SMD Resistors
  • 1x 330 ohm (0805)
  • 1x 1k ohm (0805)
  • 3x 10k ohm (0805)
• SMD Capacitors
  • 2x 22pF (0805)
  • 2x 100nF (0805)
  • 20x 100nF (0603)

Tools and Equipment

• Soldering Iron and Reflow Gun
• Solder and solder paste

Services Used

• 3D Printing
• Laser Cutting

Step 2: Getting the PCBs Ready

Thanks to JLCPCB for sponsoring the product and sending out PCBs for it.

JLCPCB offers excellent quality PCB at very affordable prices. They offer PCB Prototyping service for as low as $2 only with express shipping. With JLCPCB you can explore a wide range of options at lower prices.

You can checkout their services at jlcpcb.com and order your PCBs for just $2 only.

You can order you custom PCBs or etch them on your own. I've attached the Gerber files below.

Step 3: Soldering Them All

I used a hot air reflow soldering for soldering on the surface mount components but you can use the stencil and oven method as well.

Step 4: Let's Go Coding...

Things to note before getting started with coding

• The temperature sensor can sense 2 different temperatures
  1. Ambient Temperature
  2. Object Temperature
• There should be a minimum of 7-8 degrees of temperature difference between the ambient and object temperature.

Now fire-up your Arduino IDE and run the code.

Step 5: The Enclosure

To enclose everything as a single unit I 3D printed a case for Costie and a laser-cut top layer out of translucent acrylic. I've attached the files below as well as you can find all the files on Project's Github Page.

Step 6: Packing Everything Together

Just put your PCB along with wireless charger in the 3D Printed case and close it with the laser-cut lid.

Step 7: Taa Daa!! It Works :D

Once you assemble everything together just put your costie on a wireless charger and Taa Daa!! You'll see the magic happening right there. Place your hot/ cold drinks on costie to see it change colours based on temperature.