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Maxim > Design Support > Technical Documents > Reference Designs > 1-Wire® Devices > APP 4206
Maxim > Design Support > Technical Documents > Reference Designs > i
Button® > APP 4206
Maxim > Design Support > Technical Documents > Reference Designs > Memory > APP 4206
Keywords: 1-Wire, master, embedded application, host interface, operating voltage, strong pullup, 1-Wire
timing, overdrive, microcontroller, FPGA, ASIC, decision worksheet
REFERENCE DESIGN 4206 INCLUDES: Tested Circuit Schematic Description
Choosing the Right 1-Wire® Master for Embedded
Applications
By: Bernhard Linke, Principal Member Technical Staff
Mar 27, 2008
Abstract: This application note presents four categories of 1-Wire master circuits for embedded
applications and discusses their capabilities and requirements in relation to available (i.e., unused)
system resources. The schematics shown here apply to short networks that do not extend beyond the
radius of 1 meter and are populated with a small number of 1-Wire slaves. Instructions and a decision
worksheet are included to identify the most cost-effective 1-Wire master for the application. The reader
should be familiar with the basics of 1-Wire communication and microcontrollers.
Introduction
The 1-Wire bus is a simple signaling scheme that performs half-duplex bidirectional communications
between a master controller and one or more slaves sharing a common data line. Both power delivery
and data communication take place over this single line, making 1-Wire devices unmatched in their
ability to provide key functions to systems where interconnect must be minimized. The 1-Wire products
provide combinations of memory, mixed-signal, and secure authentication functions through a single-
contact serial interface. Typical applications of 1-Wire devices are: identification of print cartridges or
medical consumables; calibration and control of rack cards; identification and authentication of printed
circuit boards, accessories, and peripherals; and protection of intellectual property, clone prevention, and
secure feature control.
To take advantage of 1-Wire technology, one needs a 1-Wire master that generates the waveforms to
identify the devices on the bus and to communicate with them. There are numerous ways to construct a
1-Wire master. This application note discusses masters for embedded applications, i.e., short networks
that do not extend beyond the radius of 1 meter and have no more than three to five 1-Wire slaves. For
designs using 1-Wire for longer lines or with a larger number of slaves, refer to application note 148,
"Guidelines for Reliable Long Line 1-Wire® Networks."
The 1-Wire masters described in this application note are compatible to host circuits that operate on a
3V to 5V supply. The circuits that do not involve protocol conversion can also be used with hosts that
operate on a supply of less than 3V. In that case, a voltage-level translator between the master and 1-
Wire slaves is needed. Application note 4477, "Reference Design of a 1-Wire® Bidirectional Voltage-
Level Translator for 1.8V to 5V," presents such a circuit. R
PUP
in this application note corresponds to R4
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