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1-Wire® Junction

Connect 1-Wire® Sensors to the screw terminal junction.

1-Wire<sup>®</sup>  Junction

Feature List

  • Easy to connect 1-Wire® sensors to your IO Expander 1-Wire® bus using screw terminals.
  • Connect as many 1-Wire® junctions as you want.
  • 100Ω inline resistor drop for distributed impedance matching.
  • Supports up to two 1-Wire® buses D1 and D2.
  • 37.2mm x 23.3mm

In order to connect as many 1-Wire® sensors on to a single wire the sensor is connected to the 1-Wire® bus as a stub, but there is an impedance mismatch at the branch point. Reflections from the end of the stub return to the main trunk, delayed only by the time it takes for the signal to travel the length of the stub. These reflections can then cause problems for the other slaves on the network. A resistor in series with the stub will reduce the severity of the mismatch and the amplitude of the reflected energy. The resistor mitigates adverse effects from stub-generated reflections on the main trunk

Guidelines for Reliable Long Line 1-Wire® Networks

RJ11 Ports
Pin Function
1 NC
2 5V
3 D1
4 Gnd
5 D2
6 NC

1-Wire Wiring® Junction

The following 1-Wire® devices are supported by the IO Expander.

Sensor Type
DS18B20 Temperature
DS18S20 Temperature
DS1822 Temperature
DS28E17 1-Wire® to I2C

1-Wire is a registered trademark of Maxim Integrated Products, Inc.