How it Works

Our Motivation

Living with other people can present many problems. One of those issues is knowing how many people are home at a given time. Perhaps you want to know if you should lock the door when leaving the house? Maybe you want to know if anyone is home to talk to when you come through the door. There is often no way of knowing this information without walking through the whole house, knocking on closed doors, or waiting for texts backs. This is a slow process, and through littleBits rapid prototyping, the Roomie Checkie was developed to allow the user to always know how many people are home.

How might we allow households to simply keep track of who is in and out of the house?

Brainstorming

The first iteration of the prototype featured three inputs and was designed to be triggered by either the motion of a person walking by or by the sound of a door shutting with the third option of a button. This was a simple circuit without any coding necessary and allowed for us to test the count function of one of the littleBits.

The inputs to the system would send a signal from a transmitter to a wireless receiver and allow for output either through the counter, a light string lighting up, or a bar graph lighting up to show the intensity. While the inputs did work, they didn't account for directionality of a person entering or leaving a room. They would only increment a counter on the wireless receiver or turn on a light indicating that somebody walked past. Because of this, we had to come up with another iteration that allowed for both incrementing and decrementing the count.

The second iteration of the prototype featured three inputs and two outputs, and was designed to be a mostly hands-free counter. By utilizing two motion sensing bits, the code bit could decipher the inputs to decided whether a person was entering or leaving.

If motion sensor A was triggered, then motion sensor B, the count would increment. Conversely if motion sensor B then motion sensor A was triggered, it would decrement the count shown on the LED display. The single LED was used to signify when the sensors were getting being activated.

The third input was a push button that, when pressed, allowed the count to be reset to zero. This functionality would aide in the case of a miscount by the system.

Final Prototype

After encountering issues with the motion sensors being too sensitive and misreading the signals, the group decided to simplify the circuit to a push button switch and a toggle switch for the inputs. This was done in the interest of completing a prototype and testing functionality, rather than getting caught up in the engineering challenges of the project.

To increment the count, the user pushes the white push-button switch. Likewise, to decrement, the toggle switch is used. Different hardware was used not only due to availability of parts, but also to provide a very basic user interface with different inputs.

Again, the LED block will display the output of the quantity of roommates home, and the single LED will illuminate when the circuit is receiving a signal from the inputs. Unfortunately, the reset feature needed to be removed due to availability of hardware.

Component Breakdown:

LED Matrix

LED

Code Bit

Toggle Switch

Button

Power Supply / Switch

Wire Split

Extension

Meet the Team

Benjamin Somerville

Mechanical Engineering 2020

Noah Ziemba

Bioengineering 2022

Spencer Zacher

Industrial Engineering 2020

This Project was developed as part of the University of Pittsburgh Swanson School of Engineering course ENGR 1716 The Art of Making: An Introduction to Hands-On System Design and Engineering

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