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Topic: "Smart" Power Strip (Read 2 times) previous topic - next topic


Jun 25, 2012, 02:57 pm Last Edit: Jun 25, 2012, 02:59 pm by SukkoPera Reason: 1

I have just discovered the Arduino world, and I thought I would use it to do something I've been longing for for quite a while.

Basically it would be a "smart" power strip. Let's say 2/4 220V (I live in Italy, you know 8)) sockets that con be powered on/off according to various criteria:

- Always ON
- Always OFF
- ON when the temperature goes ABOVE a certain threshold
- ON when the temperature goes BELOW a certain threshold
- ON at a certain time

The criterion will be configurable per socket, through a web interface which will also allow access to the current status. It would be an improved version of what can be seen at http://www.civade.com/post/2009/07/25/40-arduino-network-power-switch-telecommander-via-ethernet-des-equipements-basse-tension-220v-relais-28j60-domotique-heyu, as I need all of this for various things I'm doing :).

Thus, some questions:

  • I'm thinking about using the Arduino Ethernet, it has everything I need and is a bit cheaper than a 2009/Uno + Ethernet Shield. Any other ideas? Luigino + Ethernet shield maybe?

  • Is there any LCD shield that is compatible with the Arduino Ethernet? This would be a later addition I'd love to make, but unfortunately all of those I've seen seem to use digital I/O 10, which is reserved for the embedded Ethernet controller. The ATS-1 (http://www.unifiedmicro.com/ats1-arduino-shield.html) seems good, but it sounds very expensive to get it from the US. I know I could wire my own LCD screen, but I'm bad at soldering, and I would happily avoid that. Plus it would be nice for my project to be entirely made of readily available parts so that everyone could build it quickly.

  • As a temperature sensor, I chose the DS18B20, as it is digital, allowing me to use longer cables, plus it is already available in a waterproof version (http://www.robot-italy.com/product_info.php?products_id=2330), which is what I need. I might as well use a thermistor, but that is more complicate, requiring a parallel resistor, soldering, etc, which - again - I'd happily avoid :).

  • On the software side I should have no problems, as programming is my job. Just one question: do you think the flash space on the ATmega328 will be enough for my project? I fear it might be too little, since I will need to use the Ethernet, SD, and - later - LCD libraries. At least I plan to put the HTML files on the SD card.

That's all for the moment, thanks in advance for any replies!


I'm thinking about using the Arduino Ethernet, it has everything I need and is a bit cheaper than a 2009/Uno + Ethernet Shield.

Yes, it is, but keep in mind, that you also need some kind of USB2Serial adapter because the Arduino Ethernet does not have that on board, the UNO has.

Is there any LCD shield that is compatible with the Arduino Ethernet?

This one http://www.nuelectronics.com/estore/index.php?main_page=project_lcd seems to be, at least the schematics does not show a usage of the SPI interface of the Ethernet shield. You might have problems though to access the SD card (pin 4).

do you think the flash space on the ATmega328 will be enough for my project?

If you include only the necessary features and put the rest on the SD card, I guess you'll have enough flash for your project.


Thanks a lot! I had seen that screen, but unfortunately it is sold out. Do things on nuelectronics usually come back in stock?

It seems that many of the Arduino-related things I'd love to get are always out of stock! :smiley-yell:


I don't know nuelectronics.com, I just searched around for a shield that uses other pins. I don't use shields for the display but solder them to connectors which I put in the topmost shield. This way I'm free to use the pins for the display that are not used otherwise.


I guess I will have to go that way. Fortunately, the LCD will be a later addition and by then, hopefully, I will have improved my soldering skills! 8)



Can anybody please give me a hint about how much size does an empty sketch take, when linked to the Ethernet and SD + FAT32 libraries?


Almost none because only the used code parts are really linked to the target binary.


Of course :). Let me rephrase that: how big are the Ethernet and SD + FAT32 libraries in the worst case?


Which of the SD+FAT libraries do you use? The standard one from the IDE?


No idea, I haven't even installed the IDE, yet. I'm still at the design phase.

Anyway, I'd use the one library you'd recommend, I guess! :D


With the version of the IDE you'll probably get about 25kB of code using most of the features.



Hi again,

a preview of my project is now available at http://arduino.cc/forum/index.php/topic,120299.0.html.


Hi,  I lived in Genova last year but now back in Vermont USA.

A display like this uses only 2 Arduino pins (Plus 5V and Ground):  http://goo.gl/psfWb  (4 line versions available also).

How-to for these displays is on http://arduinoinfo.info  here: http://arduino-info.wikispaces.com/LCD-Blue-I2C

If you use relays to control the outlets, look at these: http://goo.gl/rG5iT 

DISCLAIMER: Mentioned stuff from my own shop...
Regards, Terry King terry@yourduino.com  - Check great prices, devices and Arduino-related boards at http://YourDuino.com
HOW-TO: http://ArduinoInfo.Info


Aug 27, 2012, 04:45 pm Last Edit: Aug 27, 2012, 04:57 pm by SukkoPera Reason: 1
Thanks, but I've found a suitable solution for the display meanwhile :). I still haven't implemented it in this project, but I have already successfully used a 2-wire connection through a shift register and the NewLiquidCrystal library. I'm even thinking of trying the one-wire solution but that will require a latching SR, which I don't have at the moment. I've much improved my soldering skills, also 8).

I also already have similar relay boards for my tests, but without the optocouplers. They were the cheapest I could find in the EU. I'd love to get yours (the 30A one in particular!) but I'm always afraid of customs duties when ordering abroad. I'm waiting for some SSR's from HK and I'm hoping they won't get hold of them :).

PS: Hope you liked Genova, it's quite close to where I live!

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