This describes how to use a potentiometer with a MCP3008 chip.
Potentiometer from Ebay: http://www.ebay.com/itm/10PCS-6mm-3pin-Knurled-Shaft-Single-Linear-B-Type-B10K-ohm-Rotary-Potentiometer-/222445944546
MCP3008 from Adafruit: https://www.adafruit.com/products/856
| <!doctype html> | |
| <title>Holy Grail Layout</title> | |
| <style> | |
| body { | |
| display: grid; | |
| grid-template-rows: 100px 1fr 100px; | |
| grid-template-columns: 200px 1fr 200px; | |
| min-height: 100vh; | |
| margin: 0 |
A maintainable application architecture requires that the UI only contain the rendering logic and execute queries and mutations against the underlying data model on the server. A maintainable architecture must not contain any logic for composing "app state" on the client as that would necessarily embed business logic in the client. App state should be persisted to the database and the client projection of it should be composed in the mid tier, and refreshed as mutations occur on the server (and after network interruption) for a highly interactive, realtime UX.
With GraphQL we are able to define an easy-to-change application-level data schema on the server that captures the types and relationships in our data, and wiring it to data sources via resolvers that leverage our db's own query language (or data-oriented, uniform service APIs) to resolve client-specified "queries" and "mutations" against the schema.
We use GraphQL to dyn
#Set up an RPi Audio project
Use the following instructions to prepare your RPi's SD Card for an audio project.
###Install an operating system. You first need to install an operating system on your RPi. Raspian should work fine. If you're using a monitor, keyboard and mouse, using an install manager is the easiest way. Just follow the instuctions for installing NOOBS.
If you are developing headless, follow the instructions for downloading and installing Raspian. You'll also need to login via ssh or a console cable. If you're on Yosemite on a Mac, [this post](http://zittlau.ca/fix-usb-serial-console-on-raspberry-
| function fbUpdatePost (idPost, thePostText) { | |
| FB.api (idPost, "post", {message: thePostText}, function (response) { | |
| console.log ("fbUpdatePost: response == " + JSON.stringify (response, undefined, 4)); | |
| }); | |
| } |
| <script type="text/javascript"> | |
| (function () { | |
| "use strict"; | |
| // once cached, the css file is stored on the client forever unless | |
| // the URL below is changed. Any change will invalidate the cache | |
| var css_href = './index_files/web-fonts.css'; | |
| // a simple event handler wrapper | |
| function on(el, ev, callback) { | |
| if (el.addEventListener) { | |
| el.addEventListener(ev, callback, false); |
Note: Up to date version now at https://github.com/lukehoban/es6features
ECMAScript 6 is the upcoming version of the ECMAScript standard. This standard is targetting ratifcation in December 2014. ES6 is a significant update to the language, and the first update to the language since ES5 was standardized in 2009. Implementation of these features in major JavaScript engines is underway now.
See the draft ES6 standard for full specification of the ECMAScript 6 language.
ES6 includes the following new features:
| div { | |
| background: url('/img/background.jpg'); | |
| } | |
| @media only screen and (-webkit-min-device-pixel-ratio: 2) { | |
| div { | |
| background-image: url('/img/background@2x.jpg'); | |
| background-size: 100px 100px; | |
| // This should match the dimensions of the original resolution image |
| <snippet> | |
| <content><
Let's have some command-line fun with curl, [jq][1], and the [new GitHub Search API][2].
Today we're looking for: