Ever needed to gauge people’s response to something? It usually entails handing out a zillion slips of paper, asking people to tick a box with a biro, gathering them all up again and manually counting the results. Yawn.

So wouldn’t it be super cool to use an e-paper tool instead? Wouldn’t it save eons of precious time, not to mention a small forest of paper? Well, wouldn’t it?

We thought so. That’s why we created this handy little PaPiRus rating machine. In hindsight, we could have called it the RatorMator or the VoterMotor, but we didn’t. So the Capacitance Emoji Keyboard Rating Machine was born. And we’re going to show you just how we did it…

To begin with, we thought it’d be good to give you an overview of our rating system.

We wanted to let people cast their votes by pressing on an emoji keyboard. Once all votes have been placed, the system collects and displays them on the E-paper before updating the results in a running total on a Facebook page every hour.

Here are a few pics of the machine:

And here’s a plan of the modules we used: (Raspberry Pi, Arduino UNO with atmega328p, RFID NRF24L01+):

Paint Your Circuit

To achieve our goal, we made use of the capacitance sensor on the emoji keyboard. And we constructed the emoji keyboard from a sheet of white paper with wires connected to the bottom, like so…

Pressing on the emoji pattern causes the corresponding emoji to be marked as pressed.

So how do we make a piece of common or garden paper sense capacitance? By this rather brilliant little trick: electric paint. Since paper is an insulator, electric paint is perfect for building a conductive circuit.

Using the paint, we drew a black circle with the wire connection on the back of the paper. Then, simply by pressing the emoji with a finger, the capacitance of the paper changed wildly.

In the pic above, the NRF24L01+ RFID module is used for the communication between Arduino and Raspberry Pi. After being pressed, the Arduino sends a signal saying which emoji was pressed to the Raspberry Pi.

Send Your Data

Then, the Raspberry Pi sends the data to the Raspberry Pi 2 from the E-paper display via the mosquito server:

How It Works

So here’s how to do it.

First, prepare your own paper keyboard.

Second, press on the paper emoji that you like. The result flashes up on the screen immediately.

Next, wait a couple of seconds while the E-paper changes to the next page.

Finally, the total accumulative result appears. And if you don’t believe us, just check out this video:

You can download the source Code from Github: https://github.com/Lilian1331/PAPIRUSepaper_votingsystem.

Woo-woo. You can now create your very own Capacitance Emoji Keyboard Rating Machine. Did you find this project useful? We hope so. But to find out, we really need some sort of rating machine we guess…

Like what you read? Why not show your appreciation by giving some love.

From a quick tap to smashing that love button and show how much you enjoyed this project.


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