Book Image

BeagleBone Essentials

By : Rodolfo Giometti
Book Image

BeagleBone Essentials

By: Rodolfo Giometti

Overview of this book

Table of Contents (18 chapters)
BeagleBone Essentials
About the Author
About the Reviewers

What is the 1-Wire bus?

The 1-Wire bus is a half-duplex and asynchronous GND. However, despite this feature, most devices have three wires: the data signal, GND, and power supply (VCC).


Let me remind you that half-duplex communication can transmit and receive but not at the same time on the bus (the data can flow in one direction only) while asynchronous means that no clock is sent along with the data.

When a device has two wires only, it must include an in-built energy storage mechanism (usually a capacitor) to store the charge to power itself during periods when the data is really exchanged; that is, the device takes its power from the data pin instead of the regular power pin, and due to this, this functioning method is called parasite mode.

The drawback of this feature is that communication with these kind of devices is slower. In fact, as shown in the following diagram, in the parasite mode, the data line must be pulled high prior to the beginning of the data transfer, for an amount...