TMP36 best practices

[bfinio]

I just tried using a TMP36 for the first time, and quickly found out the hard way that basic tutorials (even from high quality sources like Adafruit and SparkFun) that just tell you to slap it on powered with 5V only work if nothing else is connected to your Arduino. A single LED can cause the 5V rail to sag a bit, which then throws off the default 5V analog reference voltage, which messes up your analogRead() value, and a few LEDs later you have a sensor telling you it's 130 deg F while sitting in a 70 deg F room.

So, many thanks to @Wawa and others who have replied in previous forum posts about this that I found very helpful. I wanted to try and create a consolidated list of best practices and clarify some things. Any corrections/suggestions for the following?

• Powering the sensor - use 3.3V, not 5V
• Analog reference - some conflicting responses in the forums about whether you should use INTERNAL, or use EXTERNAL and connect the pin to 3.3V. So far I have had more success with internal - in theory this might not work for higher temperature ranges if your analog input exceeds 1.1V, but I am only dealing with room-temperature-ish.
• Powering the Arduino - use the barrel jack, not USB (although I wonder if this changes if you're using a USB wall adapter/phone charger as opposed to a computer's USB port? Have not tried messing with power supply, have just been on computer USB the whole time)
• Sensor ground - connect directly to its own GND pin on the Arduino, do not share breadboard ground with the rest of the circuit (I noticed a massive difference with this one)
• Anything else?

Thanks!

Some of the previous threads I've found for reference:

TMP36 temperature sensor giving incorrect readings

Hi all, I'm currently attempting to get a TMP36 analog temperature sensor working with my Mega 2560, but running into some trouble. I've tried using a couple of guides to help with my code, but they're all pretty similar, and I get the same results on the few slightly different code layouts I've used. This is the code I have currently: int sensePin = A8; //This is the Arduino Pin that will read the sensor output int sensorInput; //The variable we will use to store the sensor input double temp;…

Very Inaccurate and Fluctuating Temperature Reading on TMP36GZ

This is my very first Arduino project, as well as my first post on this forum, so please be nice I need some help here... My body temperature is showing up as ~ 70 degrees Celsius (my room temperature reads at ~67) and the reading fluctuates a lot! I am using an Arduino UNO, a 16x2 LCD, and a TMP36GZ temperature sensor (along with a 220 ohm resistor and a potentiometer). These all came in the Arduino starter kit. I followed the instructions EXACTLY from the Arduino starter kit …

TMP36 unstable when controlling 12V led strip

Hello, I'm controlling 12V LED strip using a tmp36 temperature sensor. The idea is: when it gets too hot -> turn the LEDs off or vice versa. I've found a very helpful youtube video, based on which I setup the whole thing like this: [image] Only in my case instead of the little lamp I've got an LED strip and instead of a motion sensor I've got a temperature sensor. Now everything is fine when I run it without the 12V power source - tmp36 is pretty stable and accurate, but as soon as I plug t…

Getting more precision out of TMP36 temperature sensor on Arduino Uno

I've been playing with Circuit #7: temperature sensor, from the Sparkfun Inventor's Kit. I've noticed that it is subject to electrical noise and have seen some methods to address that. I'm also currently just averaging lots of readings to get better stability. Except for when my hand gets near it, that works OK. The issue I have is with the 10 bit ADC which operates over a 0-5V range trying to deal with output that operates under 1.0V (I would hate to be in a 50C room!). To do this I employed th…

TMP36 Accuracy and Margin of Error

I recently attempted to use my Uno R3 and TMP36 sensor to start a basic home automation project. I connected the sensor following the intro guide here (https://www.sparkfun.com/tutorial/AIK/ARDX-EG-SPAR-WEB.pdf) It's pretty straight forward, and I was able to get my temperature readings to the console. However, the average temperature was roughly 30-40 degrees below actual ambient temperature, and fluctuated +/- 10 degrees between readings each second. How do I go about diagnosing the problem? T…

[flashko]

@bfinio

Anything else?

I had problems with the TMP35 analog sensor and then just switched to the DS18B20 digital sensor. I don't even think about bothering with an analog temperature sensor anymore.