TMP37 pin connections.

Arduino TMP37 Analog Temperature Sensor

by Lewis Loflin

Mfr. Part # TMP37FT9Z
Mouser Part # 584-TMP37FT9Z
Cost June 2022: ~$2 QTY. 1

Note this page uses an I2C LCD display. To use a directly connected HD44780 display see:

Arduino TMP37 Temperature Sensor Tutorial

For better accuracy consider Arduino ADS1115 with TMP37 to Measure Temperature

The ADS1115 is an I2C device that delivers 12-bit accuracy.

Here we will learn how to connect a basic Arduino module to a HD44780 based liquid crystal display and use this to display in Fahrenheit the output of an Analog Devices TMP37 temperature sensor.

Download Arduino code tmp37a.txt. Copy-paste to Arduino compiler.

In this project pin 1 is connected to +5 volts, pin 2 to the analog 0 input on the Arduino module, and pin 3 to ground.

About the Program

An analog to digital converter (ADC) in the ATMEGA168 or ATMEGA328 are 10-bit (1024 steps) and over a range of 5 volts is 5.0/1024 = 4.882 mV per step. The TMP37 produces an output of 20 mV / degrees C.

It's easy to see they don't divide equally. Using the original sample program that came with the part when I ordered worked, but was unstable to the extreme bouncing around as much as ten degrees.

So beside rewriting the code to work with a LCD display instead of a computer serial port, I had to deal with the fact we were using very small real numbers and the fact the hardware didn't exactly match. But accuracy came out within a few degrees with a good 5-volt supply.

This produced both a stable reading within 1.5 degrees of a laboratory analog thermometer. (I don't have digital version.)

YouTube video for this project: Arduino TMP37 Temperature Display

Also see Arduino TMP37 Centigrade Temperature Sensor Tutorial

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