A very low cost network of smart sensors for renewables monitoring

[KenB]

Over the weekend I have been up in North Wales developing a low cost network of interconnected microcontrollers with my friends at openenergymonitor.org.

http://sustburbia.blogspot.com/2010/08/wired-network-for-arduinos.html

The hardware is based on the popular Arduino, but the techniques could be applied to any small micro.  The system was developed as part of a monitoring system for a small demonstration pV installation.  It is a way of distributing smart sensors around a domestic scale network - where each group of sensors is controlled by a slave microcontroller.  Slaves can be made for as little as £5 and the build methods are appropriate to DIY construction on breadboard or stripboard.

It consists of a master unit, which can be as simple as a PC with a USB-serial port, and a series of slave units connected to a star or daisy-chained wired network.  We used a mix of CAT5 network cable and 4 core telephone cable, and we had successful data transmission and reception at distances of 300m. The network carries the pair of data lines plus power and ground to power the remote slaves.

Another application of the network is for sending data to a remote display. A handy LCD in the kitchen or livingroom which tells you the status of your renewable installations.

This work has been done as a contribution to the Navitrino Project.  

The story starts here:

http://sustburbia.blogspot.com/2010/08/snowdonia-weekend-hack-session.html

and I've summarised the whole month of development here:

http://sustburbia.blogspot.com/2010/09/september.html




Ken
 

[Ted]

Hi Ken, great report of progress.  I've blogged your blog on my blog - http://www.caerdelyn.co.uk/blogg/

(Some design glitches in your blog - if you click on a blog link in your Twitter Update list it opens in the same column making it unreadable. You need to add a target="_blank" to the links in there so that they open in a new window.)

[KenB]

Thanks Ted,

The weekend was a lot of fun - but I did find the 5'4" doorway in the old Welsh cottage a bit inconvenient.

We now have a means to connect up the various renewable projects (electricity monitor, solar water controller and pV/battery monitor) which the lads at openenergy.org have been working on.  Trystan is busy developing software so that we will end up with a comprehensive series of commands to monitor and control the slaves.

I got the ethernet control part working through the Pachube data service, so it is now possible for a device on the serial network to send data or commands via Pachube to any slave device on another network via the ethernet enabled master.

We are now developing an extension to the slave device firmware - such that it can be programmed over the local serial network from a remote laptop.



Ken

[Ted]

I got the ethernet control part working through the Pachube data service, so it is now possible for a device on the serial network to send data or commands via Pachube to any slave device on another network via the ethernet enabled master.

Pardon me if I may have missed this before (more likely read it but completely forgot if it was discussed) - but what is the security model for that?

[KenB]

Ted,

Fairly simple approach to security

Pachube uses a 64 character API security key which is issued to you when you request an account from them.

Any device which wants to access your feed, needs to have this API key programmed into it.

It is up to the account holder to keep their API key private.


Ken

[clivejo]

I know this is totally off subject but have you heard of the HomePlug standard?

I just thought it would be a brilliant business idea to have HomePlug enabled sensors and switches that could be placed anywhere on your mains system, all communicating and working together.  This way no new wires need to be laid.

Atheros make a single chip with ethernet controller built in (http://www.atheros.com/pt/plc/products/products.html)  anyone got the electronics know how to make this work?

[ThermoSense]

Those of you interested in measuring Temperature and Temperature Difference to measure Heat Energy Flow may

be interested in our site www.sustainabilitymeasurement.com

ThermoSoft Mk1 Software is free and you do not have to buy the 1 wire temperature sensor hadware from us.

Some of the free articles may be of interest  ----- past Renewable Course Co-ordinator -Swinburne Uni Australia.

Regards  ------- Andrew Reid

[StBarnabas]

Andrew
Martin will have his  filter out but given your geographical distance, Australia etc. I view this as genuine.

the web site looks interesting. I note you have a link to FORTH which brought back some memories - Reverse Polish Notation if I remember correctly. What language is the software written in and under what operating systems will it work?

Sean

[roscoe]

Ken,

When/Are there any ways to buy prototypes for LowCost master/slave boards ?

Seems to me like there is a definite fork here. 

1.. The very attractive price of a single board based on the very cheap ENC ethernet
or
2.. The Arduino standard Wiznet 5100 (complete with SD memory socket which dilutes the cost differential)

Of course a revised Arduino ethernet board is due soon with improved functionally for PoE and remote programming over TFTP.  I 'guess' the same price ballbark as the existing ~£35 but with greater support and convenience which is of value in these low-volume-hobby 'sports'.

Any ideas how to fund some manufacturing to encourage some more developers to enter the fray ? Seems a shame that your great work can't be pushed forward due to lack to kits/boards.  Anybody from Hong Kong ebay listening ?

[KenB]

Roscoe,

I have yet to proceed with getting master/slave boards made.  Other things, plus my day job got in the way of much more progress on this front.

I was holding back on releasing the board, because I wanted to be sure that I had the right functional mix on board.  When you try to develop a board that will have the widest appeal, you need to maintain certain compatability.

My original idea for the Ether-duino was an Arduino sized board, which used the standard Arduino I/O footprint.  That would allow standard shields to be used.  However, I was not sure whether many shields would be utilised - because some of the key I/O is committed to running the ENC28J60 device. Additionally, I didn't want to perpetuate the "blighted" Arduino connector configuration.

Meanwhile I have been building a couple of "stripboard Arduinos" - which is the minimum Arduino compatible hardware, on a piece of Veroboard.  One was destined to be a Lister spark ignition controller - and is now sunning itself in California on a Lister woodgas conversion. The other is going to be a general purpose controller with extended I/O and a SDcard for datalogging.

Details on my blog here:

http://sustburbia.blogspot.com/2010/10/arduinoids-rise-of-machines.html

When you think that basic Arduino compatability can be achieved with little more than the microcontroller, a crystal and a voltage regulator - about £4.50 worth, and that fresh ATmega328 chips can be programmed with the Arduino bootloader using an Arduino itself as the ISP programmer.




Ken

[roscoe]

Ken,

Maybe a few decades ago I would have the motivation to build boards like this, but with the advent of ebay and the low cost world postal system I 'expect' that I can find an assembled solution.  I don't have a decent soldering station, stock of components and tools to do it anyway, nor do I live near a 'hackspace'.
This leaves the likes of me in a swithering dilemma, whilst highly impressed and attracted to your simple and economic solution. I can't get it.  So for a few pints more its back to mainstream arduino offerings eg arduino+ethernet ~£24 or full proper new one for ~ £45.  For myself the extra money pays its way in time, because I am not a practising/hobbyist electronics person.

Your vision has remained firm, get the cost down and provide 'sufficient' functionality.  I think the £12.50 ethernet node / £5 slave node is incredible, but restricted to electronics types that have the gear to whip up a board.  I think your design is good enough for a first release, preferably fully assembled, would it cost much more at low volumes of ~500 ?

What thoughts do have to get more of your reference design in use ?
ie who can help get some boards produced ...

[Baz]

Very much with you there Roscoe (except low cost postal system?). Plus I suffer from 'round toit' syndrome. Hence cruising the forum instead of plugging the soldering iron in. Not renewing the TV licence might save me some time but the view in the new WBS window is so distracting.....

[roscoe]

baz, what I meant was things like £12 and free postage from hong kong for a 328 arduino clone etc

[KenB]

Roscoe,

The problem I found is that I just did not have enough real Arduinos for all the stuff I wanted to connect them to. 

I didn't want to shell out £17 for a '328 Arduino, and then have to build something on veroboard anyway each time I wanted to use the Arduino in a project.

IMHO, the standard Arduino was blighted by it's badly positioned connectors, and so the Nano is far better if you need to mount it onto stripboard.  You also get two extra ADC channels.

It's probably not cost-effective me spending hours of my weekend bulding these things, but it's a poor show if all you think of is time costed at commercial rates.   My weekends spent tinkering with Arduinos has taught me the basics of C programming and now I am programming a blisteringly fast 32-bit DSP in C as my day job. I think the hours were a good investment in my future skill set.

I am glad that the Arduino project has opened up a whole new generation to the joys of tinkering with real electronic hardware, and what you can achieve with a bit of time and thought.  Kids have to realise that they can do stuff for themselves and not rely on ready made stuff shipped cross from Hong Kong.

It's horses for courses - a few of us on this forum do still have to keep plugging away at irritating hardware, whilst the rest of the world seems content writing application software for the latest Android phone.

I'll keep on at the hardware - whilst I can still see the bits ;-)



Ken

[ericw]

Something like this http://www.elechouse.com/elechouse/index.php?main_page=product_info&products_id=558 would seem to useful - if it was at a more reasonable price.