albundy wrote: ↑
Mon Jan 21, 2013 3:45 pm
I asked the same question to the manufacturer. They replied:
Yes, you can make VDD = 5V and Vpullup = 3.3V. The Data line (DQ)
is open-drain so it can only go as high as the Vpullup voltage.
So it seems to be safe to connect the VDD of the DS18B20 to +5V and still keep the dataline at max 3V3 for the raspi.
This way it must be possble to use longer cables to connect the DS18B20.
I'm aware this is a very old topic, but I have problems with long wires and star topology and I'm trying every possible I can.
Is this the correct schema:
I want to connect DS18B20 gnd to gnd of PI, 5V from PI to DS18B20 VDD and GPIO4 to the data line of DS18B20.
Because DS18B20 needs a 4,7k resistor I want to add a resistor between the data line and 3.3V on Pi.
The last thing I wast is to damage my pi, so is someone can confirm if this is valid. Thank You