THE FINAL FRONTIER

For the final, I started with the step-response "HelloTxRx" board and wanted to reconfigure it to be able to measure how full a glass of liquid is. I also wanted to improve on the design by adding a crystal for better timing, and use CAD in conjunction with EAGLE. I wanted to take that signal and send a tweet via WiFi to let the bartender know you needed another drink. Seemed simple enough....

About the Project:

• What does it do?

BrewNet measures how much beer you have in your glass and tweets the handle @Brew_Network to say you need another beer.
• Who's done what beforehand?

Neil has created all the pieces, I'm just putting them together.
• What did you design?

I worked through the individual components one by one and fabricated everything myself. I designed the board and I designed the object it sits on.
• What materials and components were used?

The initial prototypes were fabricated on an aluminum base that was waterjet cut at Autodesk, and the pads were cut on the vinyl cutter out of copper.
• Where did the materials come from?

Aluminum was supplied by Autodesk and the rest of the materials were provided by Harvard Science Center as part of the How To Make Almost Anything section.
• How much did they cost?

This project is about $30 or $40 in parts total, with cost-saving measures available.
• What parts and systems were made?

Everything was fabricated from scratch except for the WiFi module and the LCD.
• What processes were used?

Waterjet cutting, lasercutting, PCB design and fabrication, input devices, output devices, molding and casting (but it was rejected).
• What questions were answered?

Was it possible to make an "Internet of Things" device that could be responsive in a casual environment?
• What are the implications?

This project expands the scope of the "Internet of Things" projects/and implies that anything (even an object as humble as a beer coaster) can be embedded with intelligence.

Here is the step-response "HelloTxRx" board.

I started by creating the diagram in EagleCAD and adding in my improvements. This part proved to be the most challenging as there was nowhere to put a generic copper sensor. Since the sensor is just some pads of any shape, EagleCAD doesn't really have tools to approximate that. I got turned around quite a bit with thinking about this project because one of the pads has both 5V+ and GND going to it, and I kept thinking this is a short circuit.

I finally worked it all out and created the upper part of the board. I exported this to Rhino for the cad. The intention was to cut the pads on the vinyl cutter out of a roll of copper to save myself some milling time, then composite that with the board. I had a lot of issues with the vinyl cutter because the Linux partition was down and printing directly from Illustrator to the vinyl cutter left me with relatively zero control.

Here is what it should look like if it was milled on one board all at once. Ideal!

HelloTxRx Program. Language: C

HelloTxRx MakeFile. Language: C

HelloTxRx Python. Language: C

Vinyl Cutter Errors. Going too fast made the traces rip up. This is what made me change the idea to a 2 piece board.

Errors on the cutter again. In theory this should work, but I was not having any luck.

Milling the board.

Cutting the copper on the Vinyl Cutter. I used transfer paper to transfer the copper to the backerboard, and placed clear transfer plastic on the backer for insulation. I cut the aluminum backer plate at Autodesk BuildSpace on the waterjet.

Mock-up of the board without the surface mounted components.

Starting to solder the components onto the board.

Here is the completed Beer Coaster! And suprise suprise, it didn't work.

I went back and created two more boards and used the TxRx Step-Response board Niel posted, and it worked.

Glamour Shot

Glamour Shot. Next steps: Add a battery. Add wifi. Add RGB LED. Add solar top.... The goal would be to have your coaster Tweet when you need a new glass of liquid.

Video. More to come...

This week I started with the step-response "HelloFTDI" board and reconfigured it to accept a read/write wifi module (ESP8266 (2.4 GHz Wi-Fi)). The goal here was to create a board that would load a webpage with the push of a button. I started by creating the electrical diagram in EAGLE and adding in the module and the necessary power conversion hardware. The ESP8266 runs on 3.3V, so a regulator was required.

I then created the traces in EAGLE. I'm actually pretty proud of this because I didn't use any 0ohm jumper resistors, and no vias. I think it looks pretty great.