Using LM35 temperature sensor with Raspberry Pi is a relatively simple task once you have a way to read and convert analog signals. Fortunately in my previous project I’ve shown how to build a basic Raspberry Pi voltmeter with ADS1015 chip. So now we just need to connect the LM35 sensor to one of ADC inputs and adjusts the output format and we have a working thermometer in Celsius. Python code is here. Schematic diagram is shown next.
For Arduino based design click here. The sensor is outputting 10mv for each 1 Celsius. So a simple normalization for 0-100 C range can be done by dividing the sensor voltage by 10mv. I’ve used LM35DT version in TO-220 package, however most commonly used is a TO-92 variant of LM35 sensor. Pay attention that these 2 packages have different pinout. GND, V+ and Vout are in different location. Make sure to connect them correctly otherwise you can damage the chip and possibly the Raspberry Pi itself as the sensor is powered by +3.3V taken directly from Raspberry board.
