Tag Archives: LM34

chipKIT Project 1: Digital thermometer using an LM34 sensor

In Tutorial 3, we learnt how to use chiKIT ADC channels to read an external analog voltage and convert it into a digital number. We also discussed about interfacing a standard Hitachi 44780-based character LCD to the chipKIT Uno32 board in Tutorial 4. Now it’s time to implement the knowledge we have gained so far to make our first practical application using chipKIT, which is a digital thermometer. Since temperature is a non-electrical entity, the first thing we need is a transducer or sensor to convert it into an electrical signal. In this project, we will use the LM34 sensor to do that, which converts the surrounding temperature into an analog electrical voltage. The sensor’s analog output is fed to an ADC channel of the chipKIT Uno32, which then process the signal and displays the temperature on LCD, in both degree Celsius and Fahrenheit scales.

Digital thermometer project

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Testing active analog temperature sensors with a multimeter

There are quite a variety of active analog temperature sensor ICs that provide an output voltage proportional to the temperature. They usually don’t require any external calibration and signal conditioning, and as such their output can be directly fed to the input of an ADC for digital processing. A few examples of such sensors are LM34, LM35, TMP35/36/37, and MCP9701. If you are having any trouble using any of these sensors in your project, here is a quick way to test if your sensor is working or not.

Testing analog temperature sensor ICs with a multimeter

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