Nearly all articles you might look for regarding trying out an MLX90614 with an Arduino contain examples of using one sensor at a time. This makes sense as probably 99% of people are going to prototype a system with only one sensor in it. Quite a few articles make the incorrect assumption that having more than one sensor in a circuit is not even possible because the device slave addresses are hard coded. They do all come out of the factory with a default slave address of 0x5A, but this can be changed with a small amount of effort.

Now I plan to use two of these MLX90614 sensors in my cloud detection project so there was no two ways about it - I need 2 sensors, hence two slave addresses. Below I am going to take a look at the code to change the slave address on one of these devices, and then a way of actually implementing the change.

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A little bit of work stemming from from the soil temperature monitoring project; this is an aside on DS18B20 temperature sensing device address discovery with the Arduino. Being that I am going to have a handful of sensors in the ground and therefore not easily accessible for identification I need to find a way of easily finding out all the device addresses in one fell swoop.

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Part two on the soil temperature monitoring project. Detailing some thoughts on how to get the sensors in to the ground in a way that will keep them protected from the underground environment. Following that, some subequent details on the construction of the sensor housings.

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This project has its roots in a chance sighting of some, what I thought were, interesting looking API parameters on the Met Office weather data submission service. I've been running a small weather station for about a year with its data output being harvested by a RaspberryPi and packed off to the Met Office observation service.

Many months ago a friend and I were idly browsing to see what other interesting data people were collecting and sending there when we spotted, to our surprise, soil temperature measurements using sensors buried at 10, 30 and 100 centimetres. These depths are certainly not arbitrary; they may represent three of the many soil horizons: A, B and C (See the Wikipedia page regarding soil horizons). This sparked off a thoughts on the possibilities of home made sensing, gathering and aggregating soil temperature readings to a service on the internet.

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This is the next installment on the cloud detection project. This time I am starting to test out hooking up an MLX90614 or two to an Arduino and try out pointing it to the sky in the aim of get some interesting results.

Just as a friendly warning: calculations done here are rough and ready - don't write to me to say that the cat died because of some experiment based on anything shown here. It's all at your own risk, however, just remember the great Mr Churchill's wise words:

The greatest lesson in life is to know that even fools are right sometimes.

With that in mind, onwards with the experiments...

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This project has its roots in a discussion I had a while back with a friend who is a keen amateur astronomer. He had been complaining to me about how he thought that there was a distinct lack of cloud free nights in our corner of Northern Lincolnshire. In fact, he suggested, the weather was so poor that it was hardly worth having a telescope at all.

Okay, so maybe that last sentence was a little exaggeration, but his argument certainly got me thinking - how many clear nights are there in the year? Being a bit of a skeptic, I am sure that the night sky is clear on many more nights than my friend suggests.

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