Charli Wilson

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since Apr 07, 2013
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cat chicken urban
Derbyshire, UK
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Recent posts by Charli Wilson

Pretty much anything! I manage to grow lemons in Derbyshire so whilst you may struggle with bananas, most things are possible!
14 hours ago
*waves* from the Nottinghamshire/Derbyshire border!
14 hours ago
I think of 'my space' of garden as an example for others to see. It isn't going to save the world, but I can ensure its fertility abundance so it is a good example- and invite people to enjoy and hopefully encourage them to give it a try. Whereas the seedballs I put on grass verges got concreted over when they resurfaced the road, the (guerilla-planted) apple trees got torn out for new housing or snapped by the vandals on the park, the pear grafts on hawthorn got cut off by the flail-mower, etc.

When houses/etc are being built anyway- surely it is better to 'rescue' the wood chip and make good use of it, than have it dragged to landfill.
1 month ago
Without sufficient light most of those things won't die- but they will slow down and go dormant. I keep citrus and ginger in a greenhouse and I'm in the UK- Winter days approx 6 hours long, all of which are almost always cloudy! Kept warm enough they don't grow- but they don't die either.
1 month ago
The bh1750 light sensor reports light intensity in lumens or lux, which I quite like. Currently my greenhouse sensor is reporting 10,000lx (shaded by some plants)
1 month ago
Hi Mike,

Your description of how I run sensors is spot on! I run a cable, have a splitter- one side goes to a sensor and the other side to another length of cable that goes onwards.. etc. However this isn't the most efficient network and you do have to build it up a bit at a time to check all sensors and splitters play nicely (my longest cable is over 70m, and I have 39 sensors on the same cable.. so not efficient can still give you a lot of options!). Remember that anything outside or in a greenhouse will rust! So you're going to want to put any connections inside waterproof boxes or something.

I've never found internet hubs of switches to work for this- they'll work for actual ethernet traffic but not for 1wire. If I want to connect  a load of sensor sin one location I use one of these:
Which I realise is a UK product! I would have thought they're found in the US as well, '1 wire hub' or '1 wire splitter' perhaps?

Certainly a star arrangement would make waterproofing easier! You can certainly just solder wires together- again I'd put the soldered connections into a waterproof box of some kind (I use waterproof IP68 junction boxes).

You'd struggle to get the sensors you've linked to to work on 1wire- so you're better off wiring them straight to your arduino (where they can use much more power). You can use any sensors but my favourites are the HTU-21D for humidity (they're like $2!), and the bh1750 light sensor, the ccs811 air quality sensor- this is obviously massively biased by what I can get hold of in the UK! All these sensors use the i2c protocol and you can usually use multiples on the pi/arduino (apart from the HTU21D)- but you can't have as long wire lengths as 1wire.
1 month ago

Ebo David wrote:
So, starting with the number of lines.  If you connect 4 or more in a group wired together, then you will need at least 4 input lines.  You will also want several output lines I would imagine -- unless you are looking at logging only. 

With a maxim 1-wire network you only need 1 line for multiple sensors ('1-wire' is a bit misleading as you actually need 3 wires- power, ground and data). The sensors all have individual addresses and the controller can talk to them individually over one data line.

Other sensors I have worked with that you may or may not be interested in
- wind speed
- wind direction
- barometric pressure
- rain gauge
- water-butt water height
- light level (lumens)
- uv light
- current sensors for production stats on a solar panel

I've not tried to run these on 1-wire though, they are controlled by and plugged into the pi itself.

You can run 1wire networks from an arduino as well:
I've always used a raspberry pi because they are made in the UK and only cost me £4! Including the ethernet this is cheaper than I can get an arduino online for.

1 month ago
Some notes on my temp sensor network at home. This is just some musings on how I made my network- it isn't by any means the only way to do it! If its not understandable let me know and I'll try to explain a bit more- I've tried to keep it at a fairly high level but I can go into more detail on things if required.
1-wire is a protocol by Maxim utilising various sensors such as temperature and humidity.

- I use DS18B20 temperature sensors in either TO92 form, or waterproof ones that come complete with cables- depending if they are internal of external.
- humidity sensors-

Some notes on building a network:

I use cat5 cable for my network, using this wiring diagram:

I connect them by terminating the cat5 cable as usual with rj45 plugs and using splitters to plug in the sensor, and to continue the wire.
Splitters: -  these are super cheap and about 50% of them actually work, they're rather jippy. - About 80% of these splitters work, but they cost a lot more.

I also use these splitters from SheepWalk Electronics (UK) for 'hubs' where I have many sensors terminating- just out of laziness:
I'm sure similar products exist in other countries.

So take your pick according to how patient you are.

If outside then the splitters go inside IP68 junction boxes, with cable glands to keep out moisture. Outside I try and protect the cable- either bury it or encase in old garden hose or similar (else you'll be really annoyed when you accidentally cut through it with a hedge trimmer). Indoors the cblaes tend to be under floorboards or embedded in walls.

Some notes on soldering the sensors:

The base unit: I use a raspberry pi. The most common 1 wire interface is a DS9094R usb interface, which I started with. As I added more sensors I started getting conflicts on the network so switched to a multi-bus i2c interface:

On the pi I use the raspbian OS, and install the owfs software to communicate with the sensors. It has a server interface whereby you can check what sensors can be seen and their values and things.

I run a python script every 10 minutes that records the temp/humidity values to a database. And have a webpage acessible in my house where you can view the current, min and max temps. It also does graphs over various time periods and various other things.
Why do I do this? Why not, I like playing with electronics. I also have a weather station I built, pi CCTV cameras.. why would I not want to monitor temperatures in my house (and garden, and greenhouse, and pond, and chicken coop.. and compost bin...)

Do set up your base unit and a few sensors and check it all works! Then add sensors one at a time. Once you have 30 sensors or so on the same bus you start to get conflicts, not all the sensors play nicely with each other. If your nice network vanishes when you add a certain sensor or splitter- replace that with a different one- the first sensor will likely work elsewhere.
1 month ago
The link was mangled by the emoji!

Am at work right now, but I shall dig out an explanation of my 1-wire network for you tomorrow!
1 month ago