Perry Yee - Laptop Cart Status Panel

Laptop Cart Status Panel

Problem

At a glance it is hard to tell how filled a laptop cart is

Design

Maximize number of inputs per pin used and use non-traditional switch detection methods.

Impact

An LED matrix shows which slots are missing at a glance

Emulator testing the analog pin for multiple digital inputs principle

How it works:

Knows resistance of each slots.
Calculates incoming R value.
Decodes resulting resistance.
From this "decryption": Locates which switches are activated.

Emulator testing larger scale of inputs into analog pins

Here's some experimentation in seeing the

limits of this method.

In theory it can do 8 inputs for every analog pin, 8 inputs x 6 pins is 48 different binary inputs. I found 6 inputs is the real limit as resistor have tolerances and 6 inputs avoids such precision.

Technical Specs:

Construction: soldered proto board, FDM 3D printing, Arduino

CAD / Analysis Software: Onshape, TinkerCAD's Arduino emulator

Overview:

The assignment: in 2 weeks, design and create a device that will sense that an object is in its proper place and provide feedback with an enclosure that meaningfully supports the design and concept of the prototype.

I had known of a method to have multiple inputs into analog pins through resistance readings, and wanted to explore this more through this project. I also wanted to challenge myself to use non-traditional sensors or buttons.

Using some conductive tape on straws, wires, and a few resistors, I was able to bring to life my experiments from the emulators and got it to work. I was espeically proud of my soldering job, first time on a proto board but from my experience soldering keyboards, it worked out well and was very organized.

Challenges:

Some solder joints had broken during transport
Unsecured wires would move and LEDs would shine when not supposed to
The straw buttons were inconsistent in detecting is a laptop had been placed in the slot
Would have liked to use an LCD but the model I had access to used too many pins

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