www.gisvold.co.uk - electronics

Driving RGB LED tape

tor — Sun, 27 Jun 2010 10:23:33 +0000

I just bought a 5 metre roll of RGB LED's - after reading this Jeelabs article. I even bought the necessary MOSfet transistors to build the driver board.

But then I came across this story - and I happen to have a BlinkM MaxM laying around

Using MaxM with flexible RGB tape
A single BlinkM MaxM can easily drive a 5 meter (16 ft) roll of the flexible RGB SMD LED tape that’s used for architectural lighting. Each roll contains 150 RGB LEDs.

Each LED in the tape is a SMD RGB "5050" LED, capable of putting out about 6000mcd. The spacing between LEDs is 3.3cm (~1.25").
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One more home control component

tor — Sun, 20 Jun 2010 18:59:09 +0000

Today I got my act together to do the next part of our home control system.

So far we have a number of sensors dotted around the house

- Temperature and humidity outside

- Temperature and humidity in the Library

- Temperature in the living room

- Whole house electricity usage

- Boiler 1 on flame sensor

- Boiler 2 on flame sensor

- Temperature in boiler cabinet

But on the output side it is rather sparse - so far we only have

- 4 lines of 20 characters LCD display controlled from server
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Technorati Tags: Arduino Array electronics Jeenode

Gas usage measurements

tor — Sat, 08 May 2010 18:07:59 +0000

The software measure our gas usage in the house is coming along slowly - I have attached a LDR to one of the Jeenodes and found out the light level when just the pilot light is on, and the light level when the burner is on.

so I can now detect the transitions when the boiler turns on and when it turns off, and from there calculate how long it was turned on for.

This all looks a bit strange at the moment :

Measuring gas usage

tor — Sat, 08 May 2010 10:22:57 +0000

For our home monitoring system I have long had a problem -

- We do measure the amount of electricity we use, and plot/graph this quite accurately

- We do use gas for heating (2 boilers) plus a hob in the kitchen.

Measuring usage of gas seems to be difficult with any easily accessible technology, and the very oldfashioned meter we have for the house will not work with any of the methods I have seen so far - as we do not have either a flashing led nor a rotating disc.

So while trying to think through this I came to the following conclusion :

- The gas usage for the hob is probably little compared to the boilers, and there is very little we can do to reduce it, therefore I will concentrate on the usage by the boilers.
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Technorati Tags: Arduino Array electronics green Jeenode

Protocol for sending data to a Jeenode

tor — Mon, 03 May 2010 12:37:21 +0000

For my home automation project I needed a general purpose protocol to send data (and text) from a server to a Jeenode:

- First to control a multi-line LCD display

- To control "things" connected to a Jeenode remotely (and wirelessly of course)

The first project is to control a set of fans mounted in a boiler cupboard that gets way too hot occasionally, and to control a display on top of the cupboard.

The temperature is already reported to the server from another Jeenode running a unmodified version of the "ROOMS" sketch reading from a temperature and humidity sensor (SHT11).
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Technorati Tags: Arduino Array electronics Jeenode Open source Ruby

Wattson power meter

tor — Sun, 21 Mar 2010 20:11:06 +0000

I've created a page for sample code for accessing data from the Wattson energy meter.

Technorati Tags: Array development electronics Open source OsX Ruby This website

LEDs Arduino and Ikea

tor — Tue, 09 Mar 2010 21:13:46 +0000

I want one of these tables from the following article:

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Technorati Tags: Arduino Array electronics Open source

Wireless displays for Arduino/Jeenode

tor — Mon, 08 Mar 2010 20:12:01 +0000

As part of my home monitoring system I needed a display that I can use at different places in the house, preferably without a full computer attached.

And ideally I should not need Ethernet cables run around the whole house, so I decided to use a Jeenode to supply the intelligence, with a LCD display attached using one of the Jeenode LCD-adapters.

So I knocked up some code on one of my Jeenodes to do the display part, and some code (in Ruby) on one of the Mac's - and this is the end result :

(Click for larger)
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Technorati Tags: Arduino Array electronics Jeenode this server

The LCD Jeeplug

tor — Sun, 28 Feb 2010 17:13:47 +0000

Getting a LCD display working with a Jeenode is easiest done using a LCD plug - but it took me much longer to get it working than I had expected.

And it all turned out to be a stupid mistake on my side :

If you can see the small potentiometer (on the top right hand side of the main chip) - it's really difficult to turn, and it controls the contrast. It turned out that it had not moved when I put a screwdriver in and turned it...

At the start I did not solder the correct 3 bridges on the card either....so lessons learnt and so on.

Technorati Tags: Arduino Array development electronics Jeenode

I got some new headphones/earphones

tor — Sat, 13 Feb 2010 11:13:46 +0000

For years I've used a set of ER6 earphones from Etymotic, and overall been reasonably satisfied.

On the negative side it's very hard to get a good enough fit to get decent bass from the earphones.

On the positive side the mechanical noise reduction (by getting them inserted properly into the ear) is fantastic, your fellow passengers on the train or plane can't hear what you are listening too - nor are you disturbed by them.

So this time around I went for the new Etymotic HF2 - with a twist, as I now have the option to get a set of custom earbuds made in Guildford (!) to get a perfect fit. But the earbuds cost the same as the HF2's - turning them into a set of very expensive earphones indeed.
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Technorati Tags: Array electronics iPhone iPod Touch ramblings

New lightsensor (for Arduno etc)

tor — Sat, 13 Feb 2010 10:57:22 +0000

This is a particularily interesting lightsensor - as is reacts to the same range of light as the human eye - and additionally uses a I2C bus that makes interfacing it to a Arduino or a Jeeduino. Indeed the Jeeduino is getting a "shield" that works with this sensor:
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Technorati Tags: Arduino Array electronics Jeenode

startmonkey

tor — Mon, 08 Feb 2010 21:42:23 +0000

You have to love these guys - I have a powergorilla - with the extra solargorilla for a sunny day (!) - and i can't fault it. It keeps me watching movies for hours on a plane while powering my laptop, while recharging my iPhone.

So their next product is:

startmonkey
Dead car battery? We've got the power...

Introducing the startmonkey - the world's smallest "jump start" system for car batteries.

In 2009, the RAC were called out a whopping 177,916 times to jumpstart cars! A flat battery was the number 1 reason they were called out for breakdown assistance during last year.
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Technorati Tags: Array Camping Car electronics

The dryer Arduino

tor — Sun, 31 Jan 2010 16:03:29 +0000

Out of sheer curiosity I decided to measure the temperature and humidity levels in the air being expelled from our tumbledryer.

So this little one was born :

(Click for larger)

I's a Jeeduino mounted on top of a batterypack (with 3 * AA batteries) and a SHT11 sensor on a set of wires to allow me to insert it into the exhaust tube. In the end I decided to put the whole assembly inside the tube, where it wirelessly sends its measurements into the rest of the house automation system

Technorati Tags: Arduino Array electronics Jeenode

Arduino programmer for Arduino

tor — Fri, 22 Jan 2010 22:12:39 +0000

Excellent - should possibly be used to keep a gang of Arduinos code synchronised.

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Technorati Tags: Arduino Array electronics

Status of our home monitoring

tor — Sun, 17 Jan 2010 17:50:40 +0000

Our home monitoring system is coming along with the addition of a set of jeenodes (see them as wireless and battery driven Arduinos)

The slave nodes look like this :

the green box houses the 3 AA batteries making this a truly wireless solution, enabling me to move this around to anywhere in the house.

At the server things look like this

Make: Arduino vs. Maple - early impressions

tor — Wed, 13 Jan 2010 19:55:49 +0000

Make has a good comparison between a standard Arduino and the maple:

For those that haven't heard, LeafLabs' Maple board is an Arduino-compatible microcontroller platform based on an STM32 ARM Cortex-M3 chip. The full feature list includes -
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Technorati Tags: Arduino Array electronics Open source

Maple - a Ardunio "clone" with a twist

tor — Wed, 13 Jan 2010 19:39:48 +0000

Interesting reading - a new Arduino "comaptible" board based on a different processor - and apparently almost 10 times as fast....
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Technorati Tags: Arduino Array electronics Open source

Ah - set the frequency band correctly on the Jeenode

tor — Tue, 12 Jan 2010 22:23:01 +0000

It turns out that the default settings for the Jeenodes frequencey band (in software) is for the 433Mhz band. Due to the mismatch with the antennae length and the noise in this band - the maximum distance between receiver and transmitter was something in the region of 1 metre of line of sight.

Changing the frequency band to 868Mhz (Command 8 C in the demo software) increases this considerably.

Currently it works well through a fairly solid concrete wall - so again I'm happy.

Technorati Tags: Arduino Array electronics Jeenode Open source

My first Jeenode transmit

tor — Tue, 12 Jan 2010 21:55:41 +0000

How exiting is this - today my replacement radio for my blown Jeenode arrived, I soldered it in (correct way around this time) and a few seconds later this appeared on the console of my receiving Jeenode :

The OK/ack's shows that valid datapackets have arrived, and that they have been acknowledged back to the transmitter.

The second to last byte (225) is the current temperature multiplied by 10, so in other words 22.5 degrees celsius.

I'm happy!

Technorati Tags: Arduino Array development electronics Jeenode Open source OsX

Cracking secure USB sticks

tor — Fri, 08 Jan 2010 16:34:08 +0000

Oh dear - it shows how wrong you may go if you believe in the marketing hype around seciruty:
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Technorati Tags: Array electronics ramblings