Temperature Sensor – Mk II

My first go at creating a simple battery powered temperature sensor was really interesting and fun to do, but, like any project, there are always way to make it better!

For my Mark II sensor, there were a few things I wanted to improve:

Mesh Networking

I’m interesting in exploring the concept of mesh networking. Within the Expressif family of devices, there are two flavors that I’m aware of; WiFi mesh and Bluetooth Low Energy Mesh. The ESP32 platform supports both of these. My current Temperature Sensor is built upon the ESP8266, but moving to the ESP32 should be straight forward.

In Progress – .

More Data

Mk I of my sensor was a simple temperature probe. I wanted to expand on this after I found the Bosch BME280 sensor. This little sensor can capture temperature, pressure and humidity. The boards I ordered work on the I2C protocol, so I’ll have to figure that out.

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MQTT Discovery

I use the Hass.io platform to manage my automation at home. It supports a simple MQTT interface for receiving data and sending commands. Typically, you would configure the devices within a config file, but it does support a discovery protocol, which allows devices to make themselves known to Hass and to provide all the information required for Hass to use them.

I would like my temperature sensors to support this mode, so that when they fire themselves up for the first time, they would register themselves automatically.

Not started.

Battery Life

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Housing

I’d like to enclose my sensor in a nice case, so that I can mount them on the wall in way that doesn’t look completely ugly!

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Low battery notifications

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Den – The Smart Hub

The Den Smart Hub is the core component of Den’s smart home offering. You need to have one in order to use any of their other products.

The Hub is responsible for remote access and firmware upgrades. It’s worth noting that the Den products will operate *without* an internet connection (once initially setup). This is something that’s important to me. I find it really frustrating that an internet outage renders most smart home stuff useless. Den have addressed that and state the app etc. will work when on the same network as the Hub. I haven’t tried this out myself, but intend to.

Setting Up

Once you’ve signed into the Den app, the first thing it asks you to do is setup your Hub. I’ve covered the unboxing of the Hub in an earlier post.

I plugged my Hub in and connected the Ethernet cable to one of my Google WiFi units. For most users, I expect they’ll just plug the Hub directly into their WiFi router.

Of course, I immediately tried to pair and failed miserably.

I then read the letter that Den supplied with my order and there, they clearly state, that I should give it 10 minutes after plugging it in to update itself. So I made a cup of tea and sat at my table to drink it.

After scanning again, it found the Hub and asked me what room it was in. I just chose Kitchen as I was there and hit finish.

Conclusion

Simple as that. The process was simple. A small indicator within the app informing me of a firmware update might have been a useful and it’s something I’ve suggested to the Den team.

Next up, install a Den light switch!

Best laid plans, part 2

After my little boo-boo with measurements, I purchased a new Wiska junction box from RS, this time with a little more width and the Sonoff relay fit perfectly! I also picked up some IP66 glands to help secure the wire from the LED strip.

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This junction box had a membrane covering each hole, so I pierced a hole in it and fed the table through. The gland then screwed into the threaded hole (what makes these Wiska boxes so great).

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I tightened it all up.

Sadly, I didn’t take any pictures of my SWA cable gland process as I did it at lunch time. This was the tricky part of my installation since it required a hacksaw. I found a great YouTube (https://www.youtube.com/watch?v=epmxqFiD9JI)  video and followed that as best I could. I didn’t have the “glanding spanners” as recommended, but I made do with pliers. I do plan on using another armoured cable to connect to the other side of the garden, so I’ll take photos of that.

Anyway, with everything installed, I dropped the box in the garden.

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You can see the thick black SWA cable and the thin LED cable. I should point out that this is not the final resting place of this box!

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The lights look pretty nice in the snow and light the garden pretty well.

This weekend I plan on getting a few metres of SWA and using the small junction box to hook up the lights on the other side of the garden!

Best laid plans…

Wanted to work on my garden LED lighting project weekend. Unfortunately, I may have made a slight miscalculation with my measurements…

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I placed an other with RS for a replacement box, this time a little wider! If all else fails I can always take the circuit board out of the case and place it directly in the junction box, but I’d rather keep it housed.

I did manage to test it out though and the lighting is effective enough.

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Maybe next weekend?

 

WiFi enabling my porch light with a Sonoff Basic Smart Switch.

Having failed to read the warning regarding neutral wires, my attempt at using a Sonoff T1 Smart Switch to control my porch light went down in flames. My plan B was to try using a Sonoff Basic WiFi Smart Switch to perform the same job. My plan to put the relay between the ceiling rose and the bulb holder. It wouldn’t be pretty, but the aim was to test utility before spending £££ on proper smart switches etc.

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As you can see, my porch light is pretty standard.

First step, I turned off the power at the fuse box. Can’t stress this one enough. Don’t go near any mains electricity until you’ve isolated the power. Don’t just turn off the light switch!! I gathered all the parts and tools I’d need.

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I then disconnected the light bulb holder, removing the little red plastic thing and the curved lid.

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Using a short piece of flex, I connected the Smart Switch directly to the light bulb holder.

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Next, I connected the Smart Switch to the cable hanging from the ceiling!

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As it was hanging a bit low in the porch now, I created a loop and used two tie-wraps to hold it in place.

As it was all hooked up, I turned the power back on. Nothing started to smoke, so I knew I’d gotten that part done okay. The green light appeared on the relay and I started the pairing process. This involved holding down a black switch on the relay for a few seconds until the green light started flashing quickly.

I then launched the EWeLink app and hit the Add Device button. The process is straight forward. When you push the button down on the device, it creates its own WiFi network. You then connect to that WiFi network, enter details of your own WiFi network (SSID and password) and it then connects itself to your EWe account.

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Following the instructions, I found the Smart Switch’s WiFi point and connected.

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Once connected, the pairing process starts.

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After a few seconds, you’ll be able to control the device! I tapped on the power and, eh voila, the light came on.

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Job done!

Smart switches and the missing neutral!

As part of my learning and experimentation with Homekit and home automation, I recently picked up some Sonoff Basic Smart Switches. I’ve successfully installed one them outside, controlling a few metres of LED strip lighting.

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It’s pretty novel to turn it on and off via Alexa or from my iPhone, but to be honest, it’s not very practical. Flicking a switch is just than saying “Alexa, <pause> turn on the side alley light”. Pause. <click>. “Ok”.  Whilst voice control gives you flexibility (hands full etc.), 99% of the time the light switch is the king.

In my quest to check whether the smart home is practical, I wanted to try out a proper, in the wall, smart switch. I’d found a few companies such as Den Automation (who I’ve actually invested in, but who’s stuff isn’t on sale yet) and Lightwave RF, who make normal looking switches (normal from a UK style). The downside is that this stuff is expensive.

Taking Lightwave for example, a single Lightwave switch will run you £60. They also require a hub or bridge, which means an additional outlay of over £120 before you can even use the switch! Spending the bones of £200 just to check whether a smart switch is useful or useless is a bit much. I needed something cheaper to get me started!

Enter the Sonoff T1 WiFi lightswitch

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I dropped £31 and bought two switches, a two-gang and a three-gang. Aesthetically, I don’t find them appealing since they are just white and I hate touch buttons, preferring something that actually clicks.

I digress. The first step with any new light switch is to actually install it in your house. For me, I wanted to get the maximum value, so I opted to replace the three gang switch in my hallway. The hallway light switch operates the hall light, the porch light and the upstairs light. Three lights that are used pretty frequently.

I started by unscrewing the switch.

Then I stopped.

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There were more wires than I expected!! I knew the upstairs light and the hallway light were three-way switched, but the porch light isn’t.

The back of the T1 looks like this:

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I was going to need some professional help! Thankfully, as my father and two of my brothers are electricians, I could get *free* professional advice.

After getting a handle on the wiring, I realised that the T1 switches just wouldn’t work. No neutral connection was available. I mistakenly the blue wire to be neutral when it is switched live. I should have paid more attention when my father was teaching me this at age 15. I checked a few more of the switches and confirmed that there was no neutral in any of them.

The listing for the Sonoff switches on Amazon does indicate that a neutral is required, but since I mistook the blue switched-live for a neutral, I went ahead and bought them. I’ll be returning them.

This was a disappointment.

My main annoyance was that I’ve only had my house completely rewired last year. I was kicking myself because this should have been something I was aware of. That said, a lost of forum entries seem to indicate that most electricians won’t add a neutral that doesn’t connect to anything. Even if I did ask my electrician to add a neutral to each switch, he could very well have said no.

At this point, I took a step back. The Sonoff switches simply weren’t going to work.

The Lightwave RF stuff was too expensive for the purpose of playing around.

I needed a plan B. I decided to put one of the Sonoff Basic Smart Switch onto my porch light. This would mean leaving it switched on at the wall, but I figured that would be okay. I’ll do another post on that soon.

UPDATE 16 Feb, 2019Den Automation now offer smart light switches that work in the UK without the need for a neutral. I’ve written a post on the pre-ordered items I received.