Problem with DS18b20

[lcarlier]

Hello,

I'm getting trouble with using my ds18b20.

Basically whenever I'm putting the power inside my Arduino nano, the sensor is getting hot to eventually be burned.

I've already saw online that it can be because of wrong wiring but in this case I'm quite confident I didn't make any mistake. See the picture below:

Does anybody would know what is wrong in my circuit?

Thanks a lot for your help.

Kind regards,

Laurent

[TheoL]

@lcarlier Not sure. But you power the DS18b20 with 5V. I've only powered it with 3.3V so far.

According to the datasheet 5v is fine. But just try 3.3V

[lcarlier]

@TheoL
Hi TheoL,

Thanks a lot for your suggestion.

I've changed the VCC of my DS18B20 to get 3.3V coming from a AMS1117 but I still get the same behaviour.
Still getting hot, and the software does not detect anything on the bus.

Would you have another idea what to check?

Thanks a lot.

Kind regards.

[TheoL]

@lcarlier It's really hard to see at the picture. In my experience components get really hot when you change polarity. Are you sure you've connected positive to positive and ground to ground?

It's been a while since I've played with the DS18b20. But I vaguely remember that you have to connect to it first. Have you tried the example sketch?

[lcarlier]

@TheoL
Here a a zoom on the DS18B20.
Orange wire is 3.3V, green is D2 and black goes to the ground.

Would it be possible that I mistake the bottom view described into the datasheet?
All example I can see online are connected like this.

I'm using the example sketch named 'Single' coming into the Arduino IDE.

Kind regards,

Laurent

[boozz]

@lcarlier:

If you use the standard sketch, supplied as example with the mysensors libraries, then you should disconnect the 3.3V (or 5V) from pin 3. the 5V should only go feed the sensor via a 4k7 resistor to pin D3 on the arduino (in my mysensors example the DS18B20 is connected to pin D3...). connect pin 3 of the DS18B20 to ground and you're good.

My connections (parasitic as far as I'm told)
5V via 4k7 resistor to pin 2 on the DS18B20 and to D3 on the arduino / mini / nano / ...
pin 1 and pin 3 from the DS18B20 to ground.

If you need more temp-sensors, just place them in parrallel across the 1st sensor.

I hope you didn't fry your sensor already...

BR,

Boozz

[DrJeff]

@lcarlier try moving your resistor to the same pins but closer to the DS18B20, right now it's not limiting the power to it. The row between the DS18B20 and the wires.

[lcarlier]

Hi,

Thanks a lot for your suggestion

@boozz
I've tried to connect the DS18B20 in parasite-powered mode. Now it is not warming anymore but the sensor is not detected by any example sketch I have tried (oneWireSearch, Single).

@DrJeff
I've tried your suggestion but it is not helping. My sensor still get warm.

I have 5 sensors and all of them are behaving the same. I have also tried with another arduino but it had the same behavior.

Here is a picture of my sensor. I believe everything is ok.

I hope I didn't buy crap.

Kind regards,

Laurent