iButton® and 1-Wire® Technology

Analog Devices' iButton devices are small, durably packaged modules, each with a globally unique digital address. An iButton uses a stainless steel 'can' as an electronic communications interface. Each can has a data contact called the 'lid', and a ground contact, called the 'base' connected to the silicon chip inside. The lid is the top of the can and the base forms the sides and the bottom of the can. The two contacts are separated by a polypropylene grommet. A flange makes it easy to attach the iButton to just about anything. Each iButton device has a unique and unalterable address laser etched onto its chip inside the can. The address can be used as a key or identifier. By simply touching the iButton device to the two contacts, communication through the 1-Wire protocol is possible.

iButtons provide the ability to deliver or record data where other products cannot, such as in very harsh environments. iButton devices can be dropped, stepped on, or scratched. Using the DS9107 capsule IP68-level solvent resistance can be achieved. iButton devices are wear-tested for 10-year durability. An iButton device is ideal for any application where information needs to follow a person or object, such as temperature and humidity data logging, access control, asset tracking, electronic cash (eCash) transactions, automatic identification, secure authentication, and many portable applications.

Analog Devices' 1-Wire products provide combinations of memory, mixed-signal, and secure authentication functions with complete operation from a single contact serial interface. With both power and communication delivered over the serial protocol, 1-Wire devices are unmatched in their ability to provide key functions to applications where microcontroller I/O resources are constrained, or system interconnect must be minimized.

The basis of 1-Wire® technology is a serial protocol using a single data line plus ground reference for communication. 1-Wire is a voltage-based digital system that works with two contacts (data and ground) for half- duplex bidirectional communication. Compared to other serial communication systems such as I²C or SPI, 1-Wire devices are designed for use in a momentary contact environment. Either disconnecting from the 1-Wire bus or a loss of contact puts the 1-Wire slaves into a defined reset state. When the voltage returns, the slaves wake up and signal their presence. With only one contact to protect, the built-in ESD protection of 1-Wire devices is extremely high. 1-Wire devices are the most economical way to add electronic functionality to nonelectronic objects for identification, authentication, and delivery of calibration data or manufacturing information.

1-Wire Interface