1-Wire bus


1-Wire bus Description

The 1-Wire may exist in a number of forms; however the bus is currently defined using a linear topology, a stubbed topology, or a star topology. The 1-Wire bus will have one Master, and some number of Slaves [1-Wire devices]. Each Slave may not have stubs longer then 3 meters in the linear topology circuit, while the stubbed topology may have stub lengths greater than 3 meters, and the star topology allows the slaves to radiate from then Master with any length.
The longest wire run from a Master to a Slave is defined as 750 meters [maximum cable length].

A typical 1-Wire interface contains a Master which utilizes a 220 ohm pull-up resistor off the net and some number of Slaves connected to the net.
Slaves residing off stubs are connected to the main line via a 150 ohm resistor to reduce reflections on the line.
In addition to the 1 transmission wire, the 1-wire bus also requires a ground [return] line.





The 1-Wire protocol uses conventional CMOS/TTL logic levels with operation specified over a supply voltage range of 2.8V to 6V.
Both master and slaves are configured as transceivers permitting bit sequential data to flow in either direction, but only one direction at a time.
The data read and written over the interface is least significant bit (LSB) first.
Other IC to IC Buses.


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Modified 6/14/15
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