Let's Get Physical: Swift + ARM Linux = ♥️

Explore using Swift3.0 with SwiftyGPIO to interact with the physical world.

Transcript

1. LET’S GET PHYSICAL SWIFT + ARM LINUX = ♥ Cameron Perry | @mistercameron | mistercameron.com
2. LET’S GET PHYSICAL OUTLINE ▸ Environment ▸ Workflow ▸ Getting Physical with GPIO
3. LET’S GET PHYSICAL ENVIRONMENT ▸ Raspberry Pi 3 + Raspbian (Debian Jessie)* ▸ Using Swift3 snapshots from iAchieved.it ▸ SPM - Swift Package Manager works now* *Big Caveat: This doesn’t always work
4. LET’S GET PHYSICAL SWIFT + WORKFLOW ▸ Doing Swift work on Linux is still a bit rough, especially on ARM computers ▸ Miss a lot of things from Xcode ▸ Emacs / Vim via X11 or terminal ▸ Atom with Swift plugins is better on X86 ▸ Stick with a Linux VM if not doing heavy GPIO work
5. readTemp
6. LET’S GET PHYSICAL OBJECTIVES ▸ Learn about GPIO on the Raspberry Pi ▸ See what Swift was capable of - SwiftyGPIO ▸ Read temperatures using a probe temp sensor ▸ glibc - sure ▸ Try threads - why not?
7. LET’S GET PHYSICAL PACKAGE MANAGER import PackageDescription let package = Package( name: "readTemp", dependencies: [ .Package(url: “https://github.com/uraimo/SwiftyGPIO.git”, majorVersion: 0) ] ) Package.swift
8. LET’S GET PHYSICAL READTEMP - HARDWARE ▸ Connect the Pi to the breadboard using a Pi Cobbler breakout ▸ Temperature Sensor (DS18B20) ▸ Orange LED indicating temp read ▸ Blue LED to indicate thread work
9. LET’S GET PHYSICAL READTEMP - SOFTWARE Read Temp Operations 1. Turn on status LED 2. Perform READ on temp sensor & parse data 3. Turn off status LED Note: Status LED left on longer than actually needed so we can visually confirm sequence of events
10. LET’S GET PHYSICAL READTEMP - SOFTWARE Threaded Operation ‣ Familiar concepts: 1. Start a new thread, blinking an LED for a few seconds (Blink Thread) 2. On main, perform a temperature read. 3. Blink Thread completes. ‣ Experienced no issues
11. import Foundation import Glibc import SwiftyGPIO //.RaspberryPi2 also works with Raspberry Pi3 let gpios = SwiftyGPIO.GPIOs(for: .RaspberryPi2) // indicator LED lit during temperature read var led = gpios[.P6]! // the LED that will blink on a separate thread var tLED = gpios[.P21]! //Clearer LED states let ON = 1 let OFF = 0
12. //You'll need to find the ID of your 1-wire temp sensor - DS18B20 let probeNames = ["28-03159199a5ff"] //The probe will show up in here so long as you have 1-wire gpio enabled let probeDirectory = "/sys/bus/w1/devices/"
13. //reads from the probe, returns temperature in degrees C func readProbe(name : String) -> Double { let path = "\(probeDirectory)\(name)/w1_slave" var outval = "" let BUFSIZE = 1024 let fp = fopen(path, "r") // try reading from /sys/bus/w1/devices/{prob name}/w1_slave if fp != nil { var buf = [CChar](repeating:CChar(0), count:BUFSIZE) while fgets(&buf, Int32(BUFSIZE), fp) != nil { outval += String(validatingUTF8:buf)! } } let temp : Double if let tempS = outval.split(byString:"t=").last, t = Double(tempS.trim()) { temp = Double(t)/1000.0 // Sensor reports in °C * 1000 } else { temp = 0.0 } return Double(temp) }
14. LET’S GET PHYSICAL RUN IT $:~/Development/swifyARM/readTemp$ swift build Cloning https://github.com/uraimo/SwiftyGPIO.git HEAD is now at d6fd508 Updated package name, new release Resolved version: 0.8.2 Compile Swift Module 'SwiftyGPIO' (4 sources) Compile Swift Module 'readTemp' (3 sources) Linking .build/debug/readTemp
15. DEMO
16. LET’S GET PHYSICAL PACKAGE MANAGER ▸ Conclusion: ▸ Package Manager (SPM) is broken Raspbian/Pi 3. ▸ You can probably use SPM on Raspberry Pi 2 ▸ You can use SPM on Beaglebone Black ▸ Why? armv7 architecture is well covered; armv8 is neglected for now ▸ Progress made with Ubuntu16 Xenial
17. LET’S GET PHYSICAL RESOURCES ▸ Companion Post: http://mistercameron.com/2016/06/ accessing-raspberry-pi-gpio-pins-with-swift/ ▸ My swiftyArm repo: https://github.com/iamcam/swiftyARM ▸ Swift3 ARM binaries, etc : http://dev.iachieved.it/ iachievedit/swift-for-arm-systems/ ▸ Compile Swift : http://dev.iachieved.it/iachievedit/building- swift-3-0-on-a-raspberry-pi-3/ ▸ SwiftyGPIO : http://github.com/uraimo/SwiftyGPIO