Where does the javascript run, anyway?

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Where does the javascript run, anyway? A beginner’s guide to js + hardware C J Silverio @ceejbot

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Tab Hunter easily located?

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I never tracked the cat.

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Then I went to a hack day.

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That’s a cat about to be tracked.

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Text Let’s talk microcontrollers. Arduino, Raspberry Pi, Beaglebone, and beyond.

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Hardware input & output What the Arduino & the Pi have in common: inputs and outputs.

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Connect to the physical world. Turn lights on & off. Run motors. Fire missiles at nodecopters. !

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General-purpose I/O aka the GPIO or the “pin”

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The super power of a microcontroller is the GPIO. The GPIO connects variables in software to physical objects: the power level on a wire is information.

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Breadboard 101 The + and – columns are connected. The rows are connected. Board +/5V ➜ + Board ground ➜ –

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Lighting an LED is simple. Power to breadboard resistor from + to long wire on the LED LED short wire to breadboard – – to board GND

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Software! Decision-making! Now we make the microcontroller do some work.

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Text Arduino Easy to start with! Lots of GPIO pins.

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Text Button: a typical circuit power, ground, control signal software on the Arduino to read its state

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We’re about to get the javascript into it.

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Johnny-Five to the rescue StandardFirmata sketch ➜ Arduino npm install johnny- five write javascript

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Async Goodness with Buttons ! var five = require('johnny-five'); var board = new five.Board(); ! board.on('ready', function() { // signal goes into arduino pin 8 var button = new five.Button(8); ! button.on('down', function() { console.log('down'); }); button.on('up', function() { console.log('up'); }); button.on('hold', function() { console.log('holding'); }); });

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Tethered. :( You need to stay connected to a host capable of running Node.js, which the Arduino is not.

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Upgrade the microcontroller! Let’s move from the early 80s to the late 90s.

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You run Linux on these. OMG.

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Decisions, decisions. Arduino tiny Arduinos Raspberry Pi Beagle cheap cheaper CPU! more CPU! 14 pins size varies 8 pins 65 pins lots of modules features vary great video more memory C++ js tethered C++ any language any language prototyping mobile projects general use, audio-vis CPU-intensive lots of connections

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Text Cat Tracker uses 2 boards Teensy on the cat, Beaglebone at the cat door

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Next gen Tessel Espruino Javascript as ﬁrst-class language

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Next steps! Go to a hack day! http://nodebots.io Run a hack day!

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http://node-ardx.org The Arduino experimenter’s guide for Javascript

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Practical Electronics for Inventors Paul Scherz & Simon Monk

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Play! Putter around. Buy two of everything because you will melt things sometimes. It’ll be okay.

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Learn strange new things. USB? Bluetooth? Serial? Radios? Reverse-engineer something!

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Go forth & build!