Doorbell Ringer - Speaker Deck

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Doorbell Ringer An intentionally complex IoT project by Ates Goral

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@atesgoral http://magnetiq.com

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http://myplanet.com

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In the beginning there was...

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Onion Omega Invention Platform for IoT

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Onion Omega Dimensions: 28.2mm x 42mm (1.1" x 1.7") CPU: Atheros AR9331 400MHZ MIPS 24K RAM: 64MB DDR2 400MHz Flash: 16MB WiFi: 802.11b/g/n 150Mbps Ethernet: 100Mbps GPIO: 18 USB: USB 2.0, Supports additional USB Hub Power: 3.3V Antenna: PCB Antenna w/ uFL Connector Power Consumption: 0.6W

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No project ideas.

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Then there was...

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Heath Zenith DL- 6505 Wireless Battery-Operated Door Chime Kit

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Wireless Doorbell “Piece of junk” —GeorgeC “Simply does NOT perform” —jtreader “Avoid this product” —Julian “Worthless Door bell” —decodenise “Worked one hot second after installed” —NotWorking “Over priced paper weight” — Straightline22

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The aha! moment

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Earlier…

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Prototype Circuit ● Using a single GPIO pin ● Over an 4N35 optocoupler ● Setting the GPIO pin output to HIGH “presses” the button ● Button sends a RF signal to the doorbell to ring it

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But, if this were to be real doorbell… ● Visitors cannot connect through USB and type commands ● Would be silly to add a new button to tell Omega to tell the old button to ring the doorbell

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IoT to the rescue! ● The natural path is to trigger the button via WiFi ● But, the Omega is behind a NAT on my WiFi at home ● Decided to run a client and not a server on the Omega

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Then tried...

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PubNub Always-on communication layer

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But, couldn’t install the SDK ● Had a plethora of options: Node.js, Python, Perl… ● Tried Node.js and Python, ran into compilation issues and gave up

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Then was recommended...

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Twitter

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Doorbell Ringer ● Python script, running as a daemon via /etc/init.d ● Uses Twitter API ● Watches live user stream of @DoorbellRinger ● Rings the bell when it sees “#ringit”

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Still, if this were to be real doorbell… ● Not convenient for visitors to tweet ● Don’t want my doorbell to ring at 3am

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Need a local trigger that is not a physical button ● Thought about using QR codes ● Visitor scans a QR code, is taken to a URL that tweets on behalf of the visitor ● Already had an OLED display for my Omega ● The same good friend recommended that I use TOTP for token generation -- what Google Authenticator uses

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Another display? ● Bigger, faster OLED ● LED ● E-paper

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Then I remembered...

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HTC Magic 2009

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Doorbell Nudger ● Node.js server running on Heroku ● Generating TOTP tokens every 30 seconds ● Shows QR code image + token value + timer ● QR code encodes a callback URL ● Callback tweets as @DoorbellNudger ● Curious hack to avoid adding an API: piggyback token value as a cookie in the image response

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Hardware upgrade...

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Some DevOps overkill

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Going the extra mile… ● Vagrant box with OpenWRT image for local development ● Travis CI runs Python tests, ● Calls webhook on Heroku when tests pass, ● Which in turn results in a tweet from @DoorbellNudger with #update ● Which in turn prompts the Python service on Omega to self-update from GitHub

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BUT SRSLY, WHY?!?!1

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Play! ● Apply skills that you use for “serious” work to “silly” projects to hone your skills ● Problem solving is fun, so invent new problems ● You don’t need a serious/real project to start experimenting with new stuff - just do silly things ● End-to-end, planned execution practice ● Pleasure of getting multiple moving parts working together ● Conversation starter (or ender) ● Fun

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New things that I’ve learned/done about in this project Optocouplers, OpenWRT (ubus, opkg, uci), Twitter API, TOTP, QR codes, Python (virtualenv, unittest), Travis CI webhooks, /etc/init.d scripts, Onion relay expansion, using USB storage as rootfs, animating a countdown pie chart in , plus more I’m probably forgetting to appreciate.

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Links, Q&A

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Links ● @atesgoral - http://magnetiq.com ● @DoorbellRinger - https://github.com/atesgoral/doorbellringer ● @DoorbellNudger - https://github.com/atesgoral/doorbellnudger ● @OnionIoT - https://onion.io/product/omega/ ● GitHub - https://github.com/atesgoral/ ● LinkedIn - https://www.linkedin.com/in/atesgoral