Siduri – an Arduino Control Smart Coaster

Siduri named after the Sumerian god of happiness and merriment, is a smart coaster for your drinks. It recognizes when a glass is near empty and then glows yellow to alert waiters that you will be in need of a refill soon.

Designed specifically for lounge and club settings, Siduri helps nightlife revelers politely draw the attention of barmaids and helps bartenders to keep the drinks flowing.

The coaster is powered by Ardunio and uses an FSR sensor that recognizes the difference in the weight of a drinking glass. A button located near the base of the coaster allows bar staff to calibrate the coaster to an unlimited amount of drinking glass types into the coaster’s memory. Hidden under the white acrylic top are three surface mount LED’s that breath a soft yellow light when the FSR sensor recognizes when a glass is 3/4 empty. The remaining materials were laser cut out of 1/8” wood to give the coaster a manly, yet classy aged feel.

If you would like to make your own smart coaster, here is how I did it:

Step 1: Materials

All electronic components were purchased from Adafruit. The remaining parts were bought from a local art store. Below are the list of materials that you will need to make Siduri.

Electronics:
1 x Arduino Florabaord
1 x Adafruit Square Force-Sensitive Resistor (FSR)
3 x LED surface mount display RGB pixels
1 x Coin cell battery holder - 6V output with on/off switch
1 x Tactile Button Switch
1 x Resistor 2.7 KOhm

Materials:
6 x wood
2 x white acrylic
6 x wires
1 x insulating tape
Adhesive backed vinyl

Tools and devices:
1 x laser printer
1 x hot melt glue gun
1 x solder iron

Step 2: Draw and Sketch Out the Parts

I began by drawing out several sketches of what I would need to build the coaster.

First I created a diagram of how I wanted to house and layer of the electronic parts inside of the coaster. I did this using the below illustrator file. Each of the parts are sized to scale.

Then I created a storyboard outlining step-by-step how I want a user to interact with it. In each instance I discovered that I would have to make adjustments to my original diagram like including a space for a button, a USB port and external access to the battery power. Edit the file for own purposes. Once you feel like you have all the necessary parts, print them out.

*Note: in the final version the FSR sensor is located on the bottom of the coaster and the battery and flora board are housed on the same level

Step 3: Print the Needed Parts and Assemble

I used a band saw to cut out  two 24in X 12in pieces of wood. Once with 1/4in wood and then again with 1/8in wood. I used the thick pieces of wood as the base for each level and the thinner pieces as the middle layers.

Once you have all the pieces, place the corresponding components in their housing. Each part should fit snuggly in their cut outs so that they don't move. Then layer one of the thin circular cut outs on top of each layer like a cake. You can use a glue gun, wood glue or crazy glue to adhere the rings to each base piece.

Step 4: Solder the Electronics

Collect thin color-coded wires. I used red, green and white. This makes it easier to identify which wires belong to each pin.

Then I sketched out where I wanted to solder each wire to the flora board. This is a really important step because once your solder wires to the flora board it is a nearly permanent bond. But don't worry you can fix it. Just clip the wires and use a soldering syringe to remove the excess solder from the flora board and try again.

Once your get a sense of which pins you want to solder do the same for the display LEDs. These are a little tricker, what important to know is that you must connect three wires to LED. They are ground, power and your LED pin. If you are using more than one LED pin follow what you did for the first pin. All of the LEDs much follow the same path one connecting to the other.

Step 5: Upload the Code

My research showed that my coaster has to account for at least 5 unique glass types, so I wrote the code to calibrate the weight of the glass to the coaster. When a full glass is placed on the coaster and the button located at base of the coaster is held down for three seconds, the coaster registers a maximum weight. When you release the button and place a half full glass on the coaster it registers a minimum weight. Then the coaster does some math and will recognize when you glass in nearly empty. When it registers this change in weight (via the FSR sensor) the LEDs will begin to “breath” – alerting a bartender that you need help.

I've tried uploading the code but its not working so i've pasted in the code below:

Step 6: Enjoy!

Step 7: Next Steps

In the near future I will be programming in a “check out” button state that breathes a soft green color (yes the color of money) so that barmaids know to close out your tab.

I'm having trouble with the programming so if any of you have any recommendations or have calibrated buttons before, I will be very appreciative.

Thanks!