ESP32 Forum

Good morning,

I can see that the Esp32S3 contains a temperature sensor.
I would like to mesure the ambient temperature using this temperature sensor but I have some questions.
Could you please help me ?

1) If I take the example of one electronic card having an Esp32S3, do you know if the gap between the ambient temperature and
the temperature measured by the temperature sensor is always the same (On the whole ambient temperature range) ?
Or does the temperature measured by the temperature sensor depends on the Esp32S3 activity ?

2) If I take the example of ten electronic cards in the same environment (Same ambient temperature), having each an Esp32S3 and the same program running at the same time (So normally the same activity), do you know if the temperatures measured by the temperature sensor of each card (at the same time) would be the same ?


So finally, is there a particular method to get the ambient temperature using the temperature sensor of the Esp32S3 ?

Thank you, this question is really important for the projet I am working on.

Have a good day,

Thomas TRUILHE

Or does the temperature measured by the temperature sensor depends on the Esp32S3 activity ?

Yes, it does.

Not the best solution to measure ambient temperature by reading temperature sensor connected to a heater. The purpose of that sensor is to measure CPU temperature: it has better thermal contact with the die than with ambient.

But if you *have to* do it this way.. How it could be done:

Yes, CPU temperature depends on CPU activity & periferials used, so you must have 1 esp32 dedicated purely to temperature measurement, you have to put this CPU into sleep between relatively rare measurements. Run CPU at lowest possible frequency. If you can - attach a heatsink: it improves contact to "ambient" i.e. to what you are trying to measure.

And even if you decide to go this way then you'll need to calibrate every single device you make. If it is just 1..5 devices it is not a problem.

Calibration is tricky: you need to heat up / cool down your CPU to known temperature, then wake up cpu , perform quick read and sleep again.

Thank you for your answers,

so I have a new question after reading your comments.
I understood that the temperature measured by the temperature sensor depends on its activity.

But if I take (Let's say) 5 esp32S3 having the same program (So the same peripherals and approximatively the same activity),
can you tell me if their temperature sensors will give me the same measure of the ambient temperature or not ?

Thank you
Have a good day.

Temperature will also be very dependant on how long do they run.

If you want some resonable precision for ambient temerature measurement, just use external temperature sensor. You can also check datasheets, application notes or some general PCB guidelines for temperature sensors to see how to minimize the measurement errors.