# Arduino + Temperature + Humidity

A simple temperature sensor using one LM35 Precision Temperature Sensor , Humidity Sensor and Arduino, so you can hookup on your future projects. The circuit will send serial information about the temperature and humidity so you can use on your computer. I have taken data from my compost. The project is related to an existing product daily dump with which anyone can convert kitchen waste into compost at home. For more details about product go to http://www.dailydump.org/content/. Digicompost displays the changes (change in temp, humidity) happening inside dump

## Step 1: Materials

– Arduino (You can use other microcontroller, but then you will need to change the code).
– LM35 Precision Centigrade Temperature Sensor, you can get from any electronic store. Here is the DATA SHEET.
– Humidity Sensor.
– Wires.

## Step 2: Setting up Arduino + Temperature

Arduino is an open-source electronics prototyping platform based on flexible, easy-to-use hardware and software. It’s intended for artists, designers, hobbyists, and anyone interested in creating interactive objects or environments. For more information log on to (http://www.arduino.cc)

Connecting a temperature sensor:
The LM35 has three legs and looks like a transistor. The two outside legs are
+5v and Ground, and the middle leg develops the sample voltage.

The Analog to Digital Converter (ADC) converts analog values into a digital approximation
based on the formula ADC Value = sample * 1024 / reference voltage (+5v). So with a +5 volt
reference, the digital approximation will = input voltage * 205. (Ex. 2.5v * 205 = 512.5)

The LM35 is a precision linear temperature sensor that supplies 10mv per degree Celsius.
This means at 15 degrees Celsius, it would produce a reading of .150v or 150 millivolts.
Putting this value into our ADC conversion ( .15v * 205 = 30.75) we can get a close
approximation of the Celsius temperature by dividing the digital input count by 2.

If the LM35 were supplied by a different reference voltage (9v or 12v) we would have
to use a different conversion method. For this circuit, dividing by 2 works well.

## Step 3: Connecting Humidity Sensor

There are two pins on to the humidity sensor one is for ground and other for out which goes on the pin 3 on to arduino. I have used a local made sensor for testing humidity/ moisture but one can go for SHT15 which have both temperature and humidity.

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