Multiple DS18B20 1-Wire Sensors in Parasitic Mode with MOSFET

Other Hardware Sensors
1

Hello,

I am trying to get readings from multiple DS18B20 1-Wire temperature sensors using the Dallas 1-wire library, but the setup fails when there are more than two sensors on the bus. I suspect that it is because there is not enough current - the DS18B20 datasheet mentions that a MOSFET should be included when using parasitic mode to create a strong pull-up. I am curious to know if controls for the MOSFET are already included in the library. Parasitic mode is the only option because the sensors I have only have two wires - one for ground and the other for data/power.

Thanks

2

I think the library only has support for using the output pin as a strong pull-up - this ought to be good enough as the Arduino output transistors are less than 40 ohms or so and can source 10mA happily without significant droop. The DS18B20 uses typically 1mA during conversion.