Messing With A TMP36 Temperature Sensor

In ITP, Networked Sensors for Development

As a part of our assignment and lab for the week, Benedetta asked us to mess around with a temperature sensor of our choosing. I had already used a DHT22 which was very easy to get going and thought I would try using the TMP36 she handed out in class. Paul and I wanted to do the lab, but unfortunately, did not have the radios. Therefore, we just decided to get the temp sensor up and running.

 

Code from adafruit example

 

Schematic

temperature_tmp36fritz

 

circuit

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analysis

Once we got everything set up, the serial monitor was printing out the voltage that the TMP36 was passing through to the analog pin and the temperature in Celsius and Fahrenheit. The temperatures were being calculated in the code using a bit of math, which I still cannot make complete sense of even after trying to piece it together after a while.

 

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However, from reading the datasheet and monitoring the results, there is clearly a direct relationship between the increase in voltage and temperature. If temperature increases, voltage increases and vice-versa. This link made me think that it was some sort of variable resistor, however, that’s clearly not the case because that’s what a thermistor is. So after digging a bit deeper, I found that the TMP36 uses a diode instead. As temperature increases, voltage increases across the diode at a know rate. Then, by amplifying the signal, it because easier to generate and analog signal that is directly proportional to temperature… (thanks Adafruit 🙂 ).

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