1-WireÔ is a digital communications protocol and electrical specification for semiconductor devices created by Dallas Semiconductor (now part of Maxim). The name is derived from the fact that it only uses 1 wire to perform bi-directional communications to the device. Most other digital protocols require the use of two or more wires to perform the same function.
A 1-Wire based system consists of three main elements: a bus master device with controlling software, the wiring and associated connectors and 1-Wire devices or slave devices. Typically the buss master is connected to a PC or some sort of micro controller. It tightly controls communications because no slave device is allowed to speak unless requested by the master, and no communication is allowed between slaves, except through the buss master. The network of devices is defined with an open drain (wired-AND) master/slave multidrop architecture that uses a resistor pull-up to a nominal 5V supply at the master. This network of devices is called the 1-Wire® Net, sometimes known as a MicroLAN. The wiring that connects the devices is typically either flat modular cable (for very short distances) or twisted pair CAT cabling. Dallas Semiconductor makes most of the 1-wire slave devices or chips on the market today. Each chip has a unique 64-bit serial number that identifies each and every 1-wire chip. These chips range from simple memory and temperature and A/D converters all the way to complete data loggers.
Typical applications for 1-wire chips have been in meteorology devices, security, and industrial monitoring. Because of its low cost, minimal requirements and unique abilities 1-wire technology is playing an increasing role in the world of intelligent sensors among other areas.
1-WireÔ is a registered trademark of Dallas Semiconductor.
