Hi everyone!
I'm new to Arduino and was working on the 3rd project of Arduino Starter Kit (Love-O-Meter) where TMP36 sensor is involved. There is no issue with the project itself and by following the instructions in the book I managed to make it working.
However during the work on the project I noticed interesting observations that I would like your advice on the root cause of such.
Board: Arduino UNO R3
IDE: Arduino IDE Version: 2.2.1 on mac
In both cases Arduino connected to laptop via USB, program is already loaded and being executed on the microcontroller.
Case 1. Measurements are expected.
Ensure Serial Monitor in the Arduino IDE is closed. Attach voltmeter to TMP36 GND and Vout. I observe expected output voltage 720mV which corresponds to ~22℃ that I have around.
Case 2. Measurements are wrong.
Open the Arduino IDE Serial Monitor. I have constant output coming in into the Serial Monitor representing the temperature interpreted by Arduino by the executing program. Output values are correct.
Now attach voltmeter to TMP36 GND and Vout. In this case
- voltmeter start to show unexpected voltage, which fluctuates frequently.
- output values coming into the Serial Monitor starts to fluctuate and became wrong as well.
If I close Serial Monitor in Arduino IDE voltmeter values going back to expected.
Please suggest on what is the explanation of the following observation?