Doorbell Ringer

Doorbell Ringer

An intentionally complex IoT project

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Ates Goral

June 08, 2016
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  1. Doorbell Ringer An intentionally complex IoT project by Ates Goral

  2. @atesgoral http://magnetiq.com

  3. http://myplanet.com

  4. In the beginning there was...

  5. Onion Omega Invention Platform for IoT

  6. None
  7. 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
  8. None
  9. No project ideas.

  10. Then there was...

  11. None
  12. Heath Zenith DL- 6505 Wireless Battery-Operated Door Chime Kit

  13. 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
  14. The aha! moment

  15. None
  16. Earlier…

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  18. None
  19. 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
  20. None
  21. 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
  22. 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
  23. Then tried...

  24. PubNub Always-on communication layer

  25. 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
  26. Then was recommended...

  27. Twitter

  28. 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”
  29. Still, if this were to be real doorbell… • Not

    convenient for visitors to tweet • Don’t want my doorbell to ring at 3am
  30. 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
  31. None
  32. Another display? • Bigger, faster OLED • LED • E-paper

  33. Then I remembered...

  34. HTC Magic 2009

  35. 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
  36. Hardware upgrade...

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  41. Some DevOps overkill

  42. 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
  43. BUT SRSLY, WHY?!?!1

  44. 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
  45. 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 <canvas>, plus more I’m probably forgetting to appreciate.
  46. Links, Q&A

  47. Links • @atesgoral - http://magnetiq.com • @DoorbellRinger - https://github.com/atesgoral/doorbell- ringer

    • @DoorbellNudger - https://github.com/atesgoral/doorbell- nudger • @OnionIoT - https://onion.io/product/omega/ • GitHub - https://github.com/atesgoral/ • LinkedIn - https://www.linkedin.com/in/atesgoral