Z-Wave

Like a Scene from The Big Bang

Ron and his desk lampOk, I feel extremely nerdy. Did you see the episode of The Big Bang where they program an IoT device to turn on a lamp by sending a signal all around the world before it gets back to the lamp to turn it on? Well, I was suddenly struck by the similarity when I got Alexa to turn on the Z-Wave light bulb in my desk lamp last night:

  • “Alexa, turn on desk lamp”
  • The voice command is picked up by the Alexa Show device on my desk and sent to Amazon cloud.
  • Alexa Smart Home converts the audio command to a “turn on desk lamp” intent and routes it to my Alexa Smart Home skill running in an Amazon Lambda in the cloud.
  • My Smart Home skill converts the intent and forwards a “turn on desk lamp” command to Particle.io.
  • Particle.io publishes the command to my Photon IoT controllers, one of which is acting as a bridge from particle.io to MQTT.
  • The Photon bridge reformats the command and publishes it to MQTT.
  • The MQTT broker is running on a Mac Mini, which then forwards it to all other devices subscribing to MQTT.
  • One of these MQTT subscribers is the smartthings-mqtt-bridge app running on the Mac Mini. It then receives the MQTT “turn on desk lamp” command, and forwards it to the Smartthings web hook over the internet.
  • (Should I mention the Wifi to router to … Nah).
  • The Smartthings server receives the command via web hook, routes it through a Groovy program running in Smartthings, and forwards the command to my Smartthings hub over the internet (and router to wifi, etc).
  • My Smartthings hub then transmits the “turn on” command over Z-Wave radio to my desk lamp light bulb.
  • And the light turns on.

Woohoo!

Alexa as Home Automation Integration Point

Over the past few months I’ve done a lot of experimenting with getting various home automation technologies to communicate with each other. For example, setup a Raspberry Pi to bridge between SmartThings and Home Assistant using MQTT. SmartThings in turned connected to my Harmony Hub. Then tied in my Patriot custom electronics devices via MQTT. What I ended up with worked, but seemed overly complex. I don’t even want to try to blog about how to reconstruct such a beast.

So that got me thinking about how to simplify things. I realized that the individual pieces are are fairly simple: SmartThings, Patriot, Harmony. Each of these provides their own Alexa smart home skill, and most of what I want to accomplish can be done entirely by Alexa. So it isn’t really necessary to try to bridge between each of those. Instead, I can let Alexa be the common interface to each of them.

So that’s what I’m trying now. I’ve removed the bridging pieces, and will be using Alexa to control everything. Things certainly are simpler now. I’m hoping that the recently announced support for Echo Buttons indicates a direction for Amazon that will allow other inputs to be used with Alexa. Amazon is holding to their “voice first” mantra, but we’ll see where this goes.

In the meantime, I’m investigating whether I can trigger an Alexa skill lambda handler directly from a Patriot device. I think it may be possible…

Making Sense of Z Devices (Z-Wave vs Zigbee)

As I stated in my last post, trying to understand and control Z-Wave and Zigbee devices sure is confusing.

Having looked at several different controllers and hubs, and used both Zigbee and Z-Wave lights, I’ve come to understand the major differences. But it is indeed confusing.

So here is my simplified, high level understanding and comparison of these two:

  • Zigbee devices are cheaper than Z-Wave.
    • For example, the cheapest light bulbs today are about $9 for Zigbee, and $17 for Z-Wave. That’s no big deal if you only need one or two. It is a big deal if you’re replacing a whole house full.
  • Zigbee is natively supported by the new Echo Plus; no extra hub required.
    • But if like me you already have Alexa, Dots, and Shows, you’ll still need a hub.
  • Z-Wave devices are certified.
    • What this means is that they should inter-operate more reliably, but that is probably why they’re more expensive.

Confusion factors:

  • Zigbee and Z-Wave are not interchangeable.
    • You cannot control a Zigbee light with a Z-Wave controller, and vs. a vs.
    • The SmartThings hub supports both, but Echo Plus supports only Zigbee, etc.
  • Light bulb advertisements on Amazon don’t always say which one is supported.
    • I was searching for Z-Wave light bulbs, and kept getting Zigbee bulbs that do not say “Zigbee”. It would be very easy to purchase the wrong type.

So caveat emptor.