Using a 3V3 pro mini to communicate on 5V one-wire bus

Hello all,

We’re making a low-power datalogger which will be used to communicate with a string of DS18B20’s, roughly 20 meters in length, 20 sensors.

At present, we have a running prototype using the 5V bus, but due to the fact that we want to conserve power as much as possible, we’re looking into using a pro-mini on 3V3 with an interal 8Mhz oscillator active. Since the whole system won’t be powered up long, we’re keen to reduce power consumption as much as possible.

In order to communicate correctly, I assume the arduio pro mini will need some kind of levelshifter to talk to the sensors, can I use a Mosfet for this like https://www.sparkfun.com/products/11978 this one? Will this work on a one-wire bus?

Thanks in advance.

The DS18B20 is actually capable of running on 3.3V just fine, that goes for supply as well as one wire.

According to its data sheet the rating is: -55°C to +125°C; VDD=3.0V to 5.5V

For one wire highs are > 3V, whichever’s lowest and lows are <= 0.8V

The only issue I can see is if you’re running the DS18B20 on 5V but if you run them on 3.3V everything’ll be fine.