Arduino Pro Mini & DS18B20

[martim]

Hi,

I tried for 2 days now to build this project https://www.mysensors.org/build/temp. Unfortunatly I am not able to get this temperature read out with a Arduino Pro Mini. When I use a Nano it works. !?!

What could be wrong here? I tried 2 different Arduino Pro Mini boards but both don't work.

What could be different between the Arduino Pro Mini and Nano?

[bjacobse]

Do have the famous 4k7 Ohm resistor from VCC to data pin? DS18B20 min voltage is 3.0V and regardless if you use a 5V or 3,3V Arduino voltage it should work.
Maybe if you use read too quick it can't get enough voltage/power to the DS18B20 in parasite power mode

[martim]

Yes, I have the 4k7 resister from VCC to data pin. The voltage is 3.3.

[bjacobse]

when compiling in Arduino IDEdo you remember to select correct Arduino board, Pro Mini and choose 3.3v 8MHz.
Tools->Board->"Arduino Pro or Pro Mini"
Tools->Board->Processor->3,3V 8MHz
Maybe if you forget this you will compile with wrong oscillator frequency and get wrong timings to your communication to DS18B20

[martim]

@bjacobse

Thanks!! Yes this was the trick! Wrong Speed!

Happy New Year!!

[bjacobse]

@martim
Good that you replied what made the trick for you, so other can read what to check
Godt Nytår

[sola]

@bjacobse
Couldn't agree more.
This might just be the problem I face.