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Arduino | OneWire Ethernet

Arduino-uno-perspective-transparentTemperature sensors can be found in many forms and sizes. However finding them for KNX/EIB can be quite difficult. And when you do find them they are expensive.

Most of the time buying an RFXCOM is the easiest solution. They work great with Oregon Scientific sensors and it’s a wireless solution.

But there are other options. The one I use is OneWire. I had a couple of DS18S20 lying around and they are really small. Already having a couple connected to my central heating and one hidden behind the thermostat I wanted to interface them to my automation system.

OneWire ArduinoI had an Arduino Duemilanove collecting dust and it has an ethernet shield. Interfacing the Arduino to OneWire is really easy. I use parasitic power mode so I only needed to connect the two bus wires and use a 4.7k pull-up resistor. My DS18S20 sensors are wired in parallel and the 5 volts is taken straight from the Arduino.

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Refrigerator Door Sensor

refrigerator002-1024x768I noticed a bit of water at the bottom of our refrigerator. It’s probably because I still need to cut a hole in the sill and put in the plastic vent but it’s one of those tasks that’s still on the to-do-list. Whilst I was cleaning the refrigerator anyway I shot a few pictures to show the sensor we put on the door. It’s a 433.92MHz DS10A Door Sensor with a longer cable attached. Mounting was easy using the supplied double-sided tape.refrigerator001-1024x768

I mounted it on the inside of the door so you hardly notice it. Has been working fine for over a year now. The DS10A itself is located underneath the kitchen cabinet behind the sill.

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Modify DS10A Door Sensor (433.92MHz)

ds10a

The wireless DS90 sensors work fine with RFXCOM. They operate at 433.92MHz and my RFXCOM has a 433.92MHz receiver. You can use them for just about anything that needs a simple On/Off sensor. The one thing wrong with them is the ridiculous price tag compared to the 310MHz version.

Fortunately, in the US, the DS10A (DS7000) can be found very cheap on eBay. Big John sells them in packs and ships to Europe. (Only takes a few days).

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