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diff --git a/share/man/man4/iicbus.4 b/share/man/man4/iicbus.4 new file mode 100644 index 000000000000..f9e5c58d467a --- /dev/null +++ b/share/man/man4/iicbus.4 @@ -0,0 +1,118 @@ +.\" Copyright (c) 1998, Nicolas Souchu +.\" All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" $FreeBSD$ +.\" +.Dd August 6, 1998 +.Dt IICBUS 4 +.Os +.Sh NAME +.Nm iicbus +.Nd I2C bus system +.Sh SYNOPSIS +.Cd "device iicbus" +.Cd "device iicbb" +.Pp +.Cd "device iic" +.Cd "device ic" +.Cd "device iicsmb" +.Sh DESCRIPTION +The +.Em iicbus +system provides a uniform, modular and architecture-independent +system for the implementation of drivers to control various I2C devices +and to utilize different I2C controllers. +.Sh I2C +I2C is an acronym for Inter Integrated Circuit bus. +The I2C bus was developed +in the early 1980's by Philips semiconductors. +Its purpose was to provide an +easy way to connect a CPU to peripheral chips in a TV-set. +.Pp +The BUS physically consists of 2 active wires and a ground connection. +The active wires, SDA and SCL, are both bidirectional. +Where SDA is the +Serial DAta line and SCL is the Serial CLock line. +.Pp +Every component hooked up to the bus has its own unique address whether it +is a CPU, LCD driver, memory, or complex function chip. +Each of these chips +can act as a receiver and/or transmitter depending on its functionality. +Obviously an LCD driver is only a receiver, while a memory or I/O chip can +both be transmitter and receiver. +Furthermore there may be one or +more BUS MASTERs. +.Pp +The BUS MASTER is the chip issuing the commands on the BUS. +In the I2C protocol +specification it is stated that the IC that initiates a data transfer on the +bus is considered the BUS MASTER. +At that time all the others are regarded to +as the BUS SLAVEs. +As mentioned before, the IC bus is a Multi-MASTER BUS. +This means that more than one IC capable of initiating data transfer can be +connected to it. +.Sh DEVICES +Some I2C device drivers are available: +.Pp +.Bl -column "Device drivers" -compact +.It Em Devices Ta Em Description +.It Sy iic Ta "general i/o operation" +.It Sy ic Ta "network IP interface" +.It Sy iicsmb Ta "I2C to SMB software bridge" +.El +.Sh INTERFACES +The I2C protocol may be implemented by hardware or software. +Software +interfaces rely on very simple hardware, usually two lines +twiddled by 2 registers. +Hardware interfaces are more intelligent and receive +8-bit characters they write to the bus according to the I2C protocol. +.Pp +I2C interfaces may act on the bus as slave devices, allowing spontaneous +bidirectional communications, thanks to the multi-master capabilities of the +I2C protocol. +.Pp +Some I2C interfaces are available: +.Pp +.Bl -column "Interface drivers" -compact +.It Em Interface Ta Em Description +.It Sy pcf Ta "Philips PCF8584 master/slave interface" +.It Sy iicbb Ta "generic bit-banging master-only driver" +.It Sy lpbb Ta "parallel port specific bit-banging interface" +.It Sy bktr Ta "Brooktree848 video chipset, hardware and software master-only interface" +.El +.Sh SEE ALSO +.Xr iicbb 4 , +.Xr lpbb 4 , +.Xr pcf 4 +.Sh HISTORY +The +.Nm +manual page first appeared in +.Fx 3.0 . +.Sh AUTHORS +This +manual page was written by +.An Nicolas Souchu . |