WEBVTT
Kind: captions
Language: en

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♪ The creme de la creme
of the chess world... ♪

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We're getting ready for the
Dunwoody College Career Fair.

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We'll be featuring a new and improved
chessboard sensor demo.

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MACHINE: White move from e2 to e4.

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[machine announcing moves]

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An Arduino scans 64 magnetic sensors,

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displays the moves on an LCD display,

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and reports the moves
with voice synthesis.

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Our GMR magnetic switch sensors
are the heart of the demo.

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The sensors are mounted
on breakout boards

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and wired to the Arduino.

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The demo has a "combination"
of elements that

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Dunwoody students "master"--
circuit-board layout,

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Arduino programming,
soldering, and wire-wrapping.

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One of our Dunwoody alumni
worked on it.

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The GMR sensors are sensitive enough

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to detect even basic magnets
with a lot of latitude.

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They accommodate a wide range 
of magnet strengths:

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380 Gauss...

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610 Gauss...

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and negative 580 Gauss.

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The sensors are activated by positive or
negative fields, which is essential

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since the magnet orientation is random.

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Here's the schematic:

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The sensors are open-collector,

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and the output transistors
turn on in the presence of a magnetic field.

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The outputs are wire-OR'ed together,
which allows 64 sensors

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to be multiplexed to 16 I/O pins.

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There's an I²C interface
to the LCD display

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and an audio amplifier
with speakers for voice synthesis.

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We used every one of the 20 Arduino I/O pins:

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16 pins for the sensor array;

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two pins for the I²C display;

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and two pins for audio.

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Here's the Arduino sketch:

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We set up the I²C

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and voice synthesis libraries,

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define the variables,

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and initialize the I/O and display.

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We set up a 2-D array
to store the piece positions.

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We use the array
to announce the color of the pieces,

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but you can use it
for game storage,

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remote communication,
or artificial intelligence.

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The setup routine displays
a splash screen

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and initializes the I/O.

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We scan rows of sensors...

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and read columns or "files"...

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And when a piece moves,
we record the time,

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convert the ranks and files
of the previous and new positions

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to coordinates,
and update the 2-D board array.

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Then we update the LCD display
and announce the move.

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This updates the clock.

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Finally, there's a procedure to call
the speech synthesis word libraries.

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Here's what we used in this demo:

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Compared to earlier chess demos,
this version has a custom circuit board,

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an LCD display, and voice synthesis.

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We also added these
3-D printed travel pegs

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to avoid the pieces clumping together
if someone bumps the board.

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We used AD024 sensors for this demo,
but there are two other

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"book move" sensors for Arduinos;

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And we have even smaller
and lower power sensors--

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a total of six sensor families,
including the AD-Series

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used in this demo.

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And unlike other sensors
that "pawn" themselves off as stable,

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these sensors "rank" best
over a wide range of

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supply voltage and temperature.

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They're sensitive,

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for wide airgaps
and exceptional operating latitude;

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low power, so you can have large arrays
without a large power supply;

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and ultraminiature, for tight spaces.

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So when it's "your move"
to specify a proximity sensor,

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don't "sacrifice."
There's no "defense"

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for cheap, sloppy Hall-effect switches.

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"Check" our Website for more information
from the magnetic sensor "masters,"

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or to order sensors or demo boards.

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Or "check" our GitHub repository
for the Arduino code.

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And if you're part of the
Dunwoody community,

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"check" out our chess demo live
at the Career Fair on October 3.

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We're always looking for talented
engineers, technicians, and interns.

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And where else can you work on
geeky stuff like this!

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Please like this video
and subscribe to our channel for updates.