IoT 101 - is a wifi-based automated home feasible

Forums › Gadgets, robotics, home automation, electronics (including wearables) › IoT 101 - is a wifi-based automated home feasible

mdf

2304 posts

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# 214908 2-Jun-2017 12:37

My IoT stuff has grown somewhat haphazardly and currently uses a mix of random protocols. I'm now trying to design something a bit more... coherent.

I had more or less settled on z-wave as the best protocol to use, but for all the benefits of z-wave, it's really expensive (though I appreciate that it may still represent good value). For example, locally sourced (RSM compliant) fibaro and aeotec light switches are like $100. Compare that to ESP8266 based stuff like sonoff that is less than $10 for the same functionality.

But obviously having dozens of wifi devices in my house is going to start to run up against the laws of physics and run the risk of performance issues (hi @sbiddle!). I've got 3 Cambium E400 wifi APs (suggested limit, 127 devices per AP, max limit 255) and I'm pretty confident I will have less than many IoT controllers. Perhaps a bigger issue is a router that will handle all those devices. I see "IoT routers" are now a thing. The ISP-supplied HG659b's 32 device limit won't cut it though. Frankly though I could buy a pretty high end router (or two!) for the cost of a dozen z-wave light switch controllers on their own.

Has anyone else got/started an automated home based on wifi? Did you separate your networks physically (maybe a dedicated router)? How many devices is a realistic limit?

If money were no object, I would definitely be going z-wave (though if money were really no object I would be thinking about an ethernet cable to every lightswitch, bulb, power socket and appliance in the house. That would be a *big* patch panel).

mattrix

193 posts

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# 1793718 2-Jun-2017 13:48

i don't think this is the forum for "make your own". (eg. can't display nicely formatted <code> tags)
I've been searching for any NZ Hacker / Maker forums but no joy (maybe one needs to be created).

Anyway:
MQTT is the way to go.

Pi3 as main node.
It has external USB Wifi dongle with good antenna.
Runs it's on Software Access Point (hostapd + dnsmasq)
It also is the MQTT broker.
It is then connected to main network via ethernet or it's built-in Wifi.

ESP8266 connect to the dedicated IOT WiFi and use the gateway address to connect to the broker.

The Pi3 could also run which ever "smart" software you use (plenty of open source free ones).
Most of these are just MQTT brokers + web interface.

Keep the nodes as "dumb" as possible.
(read temperature, send temperature)
(wait for command, switch relay)

Do all data processing / storage on the main node.
Do any internet related stuff via the Pi3.

SumnerBoy

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# 1793794 2-Jun-2017 15:22

+1 for MQTT if you are DIY'ing. Personally I see a place for both WIFI and Z-Wave.

The in-wall Z-Wave relays are hard to beat for a few reasons;

1. NZ certified and compliant (if installed by a qualified electrician)

2. small enough to fit inside existing flush boxes

3. invisible both visually and functionally - i.e. the existing wall switch will still turn the light on/off, the user has no clue of the *smarts* behind it.

4. z-wave mesh network is very effective once you start adding more and more nodes

Trying to control existing lighting with something like a Sonoff is not as straight forward;

1. they are not certified, not sparky will install one and put their name to it.

2. they won't fit inside a flush box

3. they don't allow the existing switch to operate the light (easily)

However for appliance or wall socket control, then the Sonoff relays can be useful, and very cost effective.

Similarly for sensors, the Z-Wave sensors are pretty good - the Fibaro Motion sensor is great IME. The battery life is impressive, it has a great form factor and can be mounted anywhere, and is very discrete. Trying to build a temp/lux/pir sensor yourself which is battery powered and discrete enough for reasonable WAF, is nigh on impossible IMO. The Xiaomi Smart Home sensors however, are a pretty good option as well - they are cheap ($US10-15), battery powered, very small form factor, and can be setup to run locally only via MQTT with a bit of tinkering.

I have a separate VLAN for all my IoT devices, and a separate IoT SSID on that VLAN via my Unifi controller. There is not a separate AP, but the Unifis allow up to 4 different SSIDs on the one device. Seems to work fine for me.

The ideal scenario is hard wiring between everything - but this is hardly ever possible. I find the ESP8266 devices like the Sonoff and Wemos D1 Minis very handy. Although I do find the Wemos struggle to swap APs once they connect to one, even if another is closer with far stronger signal. I have to hard restart them each time I upgrade the Unifi firmware as the Wemos D1s connect to which ever AP comes up first and refuse to jump to the stronger signal once the other APs come up.

onebytemike

87 posts

Master Geek

# 1793810 2-Jun-2017 15:42

I've got ESP based sensor nodes throughout my house but further expansion will be via zwave. Not because of wifi limitations but because zwave sensors are small and power efficient.

filboz

16 posts

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# 1793821 2-Jun-2017 16:05

Have you seen mysensors.org?

"A MySensor radio network can consist of up to 254 different radio nodes and each radio node can report data for 254 attached child sensors. This means that you can, in theory, manage data for up to 64516 sensors in a single radio network. If this isn't enough, you can create another parallel radio network on a different channel and there are 126 available channels [NRF24L01+]."

Talkiet

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# 1793822 2-Jun-2017 16:10

I'm in the middle of a new house build and I couldn't find a better solution that z-wave everywhere... It's probably one of the most expensive options, but it's definitely the most transparent and seemingly easiest options.

Cheers - N

Please note all comments are the product of my own brain and don't necessarily represent the position or opinions of my employer, previous employers, colleagues, friends or pets.