Linrose Tricolor<\/a> LED lying around so I decided to put it to good use with Swift. In this code example we’ve written a command line application that lets you set the color of the LED (or to turn it off). I’ve marked the code with `\/\/ 1`, `\/\/ 2` to describe each section.<\/p>\n\r\nimport Glibc\r\n\r\n\/\/ 1\r\nlet gpiodefs = SwiftyGPIO.getGPIOsForBoard(.RaspberryPiPlus2Zero)\r\n\r\n\/\/ 2\r\nenum GPIOState:Int {\r\ncase Off = 0\r\ncase On \r\n}\r\n\r\n\/\/ 3\r\nstruct LedColor {\r\n static let Off = (GPIOState.Off, GPIOState.Off) \r\n static let Green = (GPIOState.On, GPIOState.Off)\r\n static let Orange = (GPIOState.On, GPIOState.On)\r\n static let Red = (GPIOState.Off, GPIOState.On)\r\n}\r\n\r\n\/\/ 4\r\nlet gpios = [gpiodefs[.P4]!, gpiodefs[.P27]!]\r\nfor gpio in gpios {\r\n gpio.direction = .OUT\r\n gpio.value = GPIOState.Off.rawValue\r\n}\r\n\r\n\/\/ 5\r\nfunc setLedColor(color:(GPIOState,GPIOState), gpios:[GPIO]) {\r\n gpios[0].value = color.0.rawValue\r\n gpios[1].value = color.1.rawValue\r\n}\r\n\r\n\/\/ 6\r\nguard Process.arguments.count == 2 else {\r\n print(\"Usage: .\/main off|green|orange|red\")\r\n exit(0)\r\n}\r\n\r\nlet color = Process.arguments[1]\r\n\r\n\/\/ 7\r\nswitch color {\r\n case \"off\":\r\n setLedColor(LedColor.Off, gpios:gpios)\r\n case \"green\":\r\n setLedColor(LedColor.Green, gpios:gpios)\r\n case \"orange\":\r\n setLedColor(LedColor.Orange, gpios:gpios)\r\n case \"red\":\r\n setLedColor(LedColor.Red, gpios:gpios)\r\n default:\r\n print(\"Invalid color\")\r\n}\r\n<\/pre>\n1.<\/b> `SwiftyGPIO` provides canned GPIO definitions for popular board types. In our case we’re using a Raspberry Pi 2.<\/p>\n
2.<\/b> This is purely syntactic sugar to describe GPIO states as `On` or `Off`. The code would probably look less cluttered if we removed this.<\/p>\n
3.<\/b> `LedColor` is a structure to “namespace” definitions for `Off`, `Green`, `Orange`, and `Red`.<\/p>\n
4.<\/b> The tricolor LED has two anode pins; we will attach one pin to GPIO4 and the other to GPIO27. The application always starts by setting the pin direction to `.OUT` and `Off`. Again, because of the way we created an `enum` for the `GPIOState` we have to use the `.rawValue` nonsense.<\/p>\n
5.<\/b> `setLedColor` takes a tuple of `(GPIOState,GPIOState)` and `[GPIO]` array to set the pair of GPIO pins to a certain state.<\/p>\n
6.<\/b> Our application takes a single argument so we `guard` that we have two (one is the application name). Our color is the second.<\/p>\n
7.<\/b> A switch on the color and a call is made to `setLedColor` with the appropriate color tuple and GPIO set.<\/p>\nClosing Remarks<\/h3>\n
SwiftyGPIO<\/a> is a great API to get started with GPIO manipulation on ARM boards with Swift. Each passing day Swift makes inroads into the maker community and stands a great chance to be the language of choice for single board computer development projects.<\/p>\n","protected":false},"excerpt":{"rendered":"Working with open source developers worldwide is a fun and rewarding experience. As the cost of computing devices and broadband Internet continues to fall and bring new technologies to people around the globe, developers of all stripes from different cultures and backgrounds come together to collaborate and build awesome things. Since Apple open sourced the […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[19,13,5],"tags":[],"class_list":["post-2528","post","type-post","status-publish","format-standard","hentry","category-linux","category-raspberry-pi","category-swift"],"_links":{"self":[{"href":"https:\/\/dev.iachieved.it\/iachievedit\/wp-json\/wp\/v2\/posts\/2528"}],"collection":[{"href":"https:\/\/dev.iachieved.it\/iachievedit\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/dev.iachieved.it\/iachievedit\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/dev.iachieved.it\/iachievedit\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/dev.iachieved.it\/iachievedit\/wp-json\/wp\/v2\/comments?post=2528"}],"version-history":[{"count":14,"href":"https:\/\/dev.iachieved.it\/iachievedit\/wp-json\/wp\/v2\/posts\/2528\/revisions"}],"predecessor-version":[{"id":2543,"href":"https:\/\/dev.iachieved.it\/iachievedit\/wp-json\/wp\/v2\/posts\/2528\/revisions\/2543"}],"wp:attachment":[{"href":"https:\/\/dev.iachieved.it\/iachievedit\/wp-json\/wp\/v2\/media?parent=2528"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/dev.iachieved.it\/iachievedit\/wp-json\/wp\/v2\/categories?post=2528"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/dev.iachieved.it\/iachievedit\/wp-json\/wp\/v2\/tags?post=2528"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
![\"Blinky](\"http:\/\/dev.iachieved.it\/iachievedit\/wp-content\/uploads\/2016\/01\/SwiftLEDs.png\")
<\/a>