Personally, I use DS18B20 which is OneWire bus device. Very accurate. Best for weather stations.

Power your motor from a different power source, keep only the ground common.

Which is correct. If the ADC reports a maximum value, then you indeed have a maximum value on the ADC pin 🙂

Try to randomize the value of ADC in your calculations. And keep in mind that the sensor will never report such high values. So, according to the datasheet of LM35, what would be the maximum reported ADC value? Or voltage in millivolts?

An accurate reading of the LM35 sensor would require you to lower the reference voltage of the ADC… I believe that ATmega328P can be set to have a reference of 1.1 volts… if I remember correctly – in which case, the formula changes accordingly.

Which is still wrong, because the correct formula is:
Vin = ADC_Res x (Reference Voltage / 4096)
Where, Reference Voltage = (VREF+) – (VREF-)

And reference voltage can be 3.3 or lower, depending of your ADC hardware configuration. Look in the datasheet.

ESP32 might be powered at 3.3 volts, and its ADC might be 12bit…

So, the formula changes:
voltageOut = (sensorValue * 3300) / 4096

So if the ADC says that the value is 1024, then (1024 * 5000) / 1024 will be 5000 volts. Which if you then divide that by 10, the temperature comes out as 500 degrees C … is it possible that the code you published is not the exact same code that you used to get the values you published?

Great tutorial! it really helped me with my project. However I still need a little push to have it fully completed.

I’m using a LM335Z sensor to activate a DC motor when it reaches a certain temperature. The sensor gives the correct temperature readings out. And these values increase or decrease correctly following the temperature changes.

When the temperature readings go above the temperature limit I´ve previously set the DC motor turns on. But just at the same exact moment the temperature readings (voltage) increases drastically and stay constant so I could never cool down the sensor so the DC motor turns off when the temperature goes under the limit temperature I´ve mentioned before.

I’m struggling with this issue and can’t really figure out what’s going on.
I am a beginner using ARDUINO and I’d really appreciate some help.

Thanks a lot!
Julen

Hi.
Yes, you are right. It corresponds to GPIO 36. So, it can read analog values.
Bur, try another GPIO, for example GPIO 32.
Regards,
Sara

I am using ESP32 DEVKIT V1 DOIT board, so I thought that VP pin could read analog reading. Where do you suggest to connect it?

Thanks