Stupidly Cheap Web Enabled Sensors!

[KenB]

Hi All,

In between my new day-job, developing equipment for teaching "renewables" to university students, I have been tinkering away at a pet project of mine - to get a microcontroller with smart sensors "online" for about a tenner.

Well, I must admit, I have failed miserably, it has cost me about £12.50 and the results are a device which can publish temperature data from six thermistors up to Pachube.

I have said for a while that the Arduino is somewhat over-hyped in terms of it's hardware - it is afterall only a £2 microcontroller with a clock circuit and programmming interface.  I applied the same critical eye to the NuElectronics ethernet shield, and decided that it was just a £2 ethernet controller, a £2 magjack RJ45 connector, a crystal and a handfull of passive components. So in theory, I could combine the circuits on a single small pcb, and get an ethernet connected microcontroller sensor board - for about a tenner.

The first job was to prove that I could make it work - so I reached for my trusty breadboard.  More experienced engineers might say that you'll never get ethernet to work on a breadboard - but until you've tried and succeeded - then the jury is out.

The results sprang into life yesterday evening - a breadboard with 3 chips and about 30 passive components - see picture.  The board is monitoring between 4 and 6 thermistor channels and sending the results up to Pachube.

http://www.pachube.com/feeds/8729 



Ken

[Stuart]

nice work, handy for keeping a eye on things while away

[davebodger]

Nice one Ken; let us know when the PCB is available - I would buy one for sure.

best regards.

Dave.

[wookey]

I'm not sure Ken's expertise is in the 'making a PCB' dept. Someone else might have to do that. Publish the schematic ken, and someone might take it further. There is a business in making this stuff open and modular, because most people just want to buy one. I'd do it if I didn't have more than enough work to do already...

I impressed that you can get DIL ethernet controllers these days!

[Baz]

brilliant. A version that had a small server would be universal, ie not need programming to a particular pachube ID.

[KenB]

Wookey,

I'm no stranger to making pcbs - I earned a crust doing it for the last 7 years.  I have teamed up with the London Hackspace to make this project as cheap and accessible to as many as possible.  You can read about the background to the project here.

http://wiki.hackspace.org.uk/wiki/Projects/Ethernet_Arduino

I can sort out the hardware, others have come forward with firmware and I'm talking to some people about the back-end applications.


Meanwhile back to Terminator 3 - the girly one.



Ken

[EccentricAnomaly]

I have said for a while that the Arduino is somewhat over-hyped in terms of it's hardware - it is afterall only a £2 microcontroller with a clock circuit and programmming interface.

Indeed, there's nothing special about the hardware.  What is nice is the packaging: you can buy a pre-programmed board, dig out a standard USB cable, install free open-source software which runs on pretty much everything (Windows, OS X, Linux...) and get programming immediately.  Other solutions are fine if you're at all serious but Arduino is great instant gratification if you are not currently into hardware much or have other things you want to get on with.

Still, I look forward to your board being available.

Any thoughts about powering over the cat 5 cable?  Either formal PoE or just using a couple of spare wires somehow.

[KenB]

EA,

I agree fully about the packaging of the Arduino project, and that is why it has gathered so much momentum over the likes of the PIC.

Microchip must be kicking themselves, but if they will stick to a quirky processor core designed in 1974 they only have themselves to blame - things have moved on a bit since the GI Peripheral Interface Controller. The AVR is such a better architechture for coding in C.

Boards will be available in about 6 weeks time - they are on a 3 week turnaround in China.



Ken

[KenB]

Been thinking about how to make the ethernet control board more useful.

We really need the web application to act as a small message broker, such that one board  can publish data, commands or serial text to the broker, and other boards can subscribe to this feed.

I wrote a serial command interpreter a couple of weeks ago which can handle commands in the form of b1,100 - which is "b" for LED brightnes, 1 for board 1 and 100 as the pwm value that you want to set the brightness to.

If the ethernet control board is basically just a transparent serial to ethernet gateway, which publishes to a certain feed and subscribes to other feeds, then these simple serial commands could be sent to any board subscribed to that feed.

Pachube already uses the concept of a control feed, but I don't yet see if this can handle serial text strings, or what exactly is sent form the Pachube API feed to the remote device.

Give me an application where I can type "Hello World" in a text box on a website, and then see it coming out of the serial Tx pin of the web enabled Arduino. Anyone know how to achieve such a seemingly useful function?



Ken

[Baz]

You seem to be trying to complicate things by tying into specialist applications.
First just make the device a simple web server as per
http://srmonk.blogspot.com/2010/03/simplified-ethernet-library-for-28j60.html
That makes the data available with the ubiquitous internet browser.
If some other pc application or home automation system wants the data it can easily get hold of it and display in a more user friendly manner, and if necessary send it on elsewhere like pachube, or out on a serial port.
Tying the basic unit to pachube is severely restrictive and requires and ID to be inserted somehow. If you want to use pachube it would be better to have a dedicated unit pulling serial and web info off several other devices to send.

If there is then still program room it could have some added features that could be enabled through the web interface, eg UDP or email or ftp messages.

Also have a look at this.
http://www.amazon.com/Webcontrol-Universal-Temperature-Humidity-Controller/dp/B001H4JXLU/ref=sr_1_1?ie=UTF8&s=electronics&qid=1256497812&sr=1-1
A good idea but with a few quirks including only sending email on change of a particular input, only using more expensive 1wire temp sensors, not shipping straight out of USA.

[wookey]

I'm no stranger to making pcbs - I earned a crust doing it for the last 7 years.  I have teamed up with the London Hackspace to make this project as cheap and accessible to as many as possible. 

Sorry Ken. I meant to suggest that you preferred developing stuff over getting PCBs made and shipping things and managing inventory etc. Not that you couldn't. But this is clearly all well under control so I'll let you all just get on with it :-)

[KenB]

Baz,

Thanks for the links but we are developing something a little different.

The intention is to use a third party as a message broker or mailbox service, and allow ethernet enabled boards to communicate with each other using a publisher/subscriber relationship.

Wookey - this project has come together only in the last 2 weeks, starting with proving the minimalist design on breadboard - but pcbs will follow along shortly. I will be spending the Bank Holiday weekend isolated in North Wales with a couple of co-developers working out the firmware for this.  Hopefully by next week we should have something useful running.

In the meantime the board is operating as a Pachube client and happily sending temperature data from a bunch of thermistors up to Pachube.

http://www.pachube.com/feeds/8729


Ken

[hiccup]

Hi Ken

I'm doing something along these lines for communications between my various systems. I've chosen xmpp as the messaging protocol. It's open, and there are loads of free clients and servers available. It also supports a publish-subscribe model.

I'm using the openfire server and a standard linux client for debugging and development.

Hic!

[roscoe]

Bravo - mighty impressed with the budget target

How can I get one ?Always a fan of convenience and ethernet fits that perfectly, but still put off even nowadays with the ridiculous extra money some charge to get an ethernet option.

Would love to do one with two pulse counters gas/3ph lecky for tennis club whacking up to google at that price is very appealing. 

aL

[KenB]

Guys,

Thanks for your interest and enthusiasm.

This project is v.much in its infancy and we are still working out the basics of getting boards to talk to each other over the net.

The whole lot will be open source, and we are hoping that it will have educational value for those wanting to learn how to connect simple microcontrollers to the internet.

At the moment there are 5 or 6 of us working on various parts of the project - it is truly a distributed development.

Just tonight a co-developer came forward with a bit of code that allows easy reading of Pachube data - an essential part of the project.

http://john.crouchley.com/blog/archives/706


Slowly the pieces of the jigsaw start to fall into place


Ken