PCF(4) BSD Kernel Interfaces Manual PCF(4)NAME
pcf -- Philips I2C bus controller
SYNOPSIS
device pcf
In /boot/device.hints:
hint.pcf.0.at="isa"
hint.pcf.0.port="0x320"
hint.pcf.0.irq="5"
For one or more iicbus busses:
device iicbus
DESCRIPTION
The pcf driver provides support to the Philips PCF8584 I2C controller for the iicbus(4) system.
The PCF8584 is an integrated circuit designed in CMOS technology which serves as an interface between most standard parallel-bus microcon-
trollers/microprocessors and the serial I2C-bus. The PCF8584 provides both master and slave functions. Communication with I2C-bus is car-
ried out on a byte-wise basis using interrupt or polled handshake. It controls all the I2C-bus specific sequences, protocol, arbitration and
timing. The PCF8584 allows parallel-bus systems to communicate bidirectionally with the I2C-bus.
SEE ALSO iicbus(4)HISTORY
The pcf manual page first appeared in FreeBSD 3.0.
AUTHORS
This manual page was written by Nicolas Souchu.
BSD August 6, 1998 BSD
Check Out this Related Man Page
IICBUS(4) BSD Kernel Interfaces Manual IICBUS(4)NAME
iicbus -- I2C bus system
SYNOPSIS
device iicbus
device iicbb
device iic
device ic
device iicsmb
DESCRIPTION
The 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.
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.
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.
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.
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.
DEVICES
Some I2C device drivers are available:
Devices Description
iic general i/o operation
ic network IP interface
iicsmb I2C to SMB software bridge
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.
I2C interfaces may act on the bus as slave devices, allowing spontaneous bidirectional communications, thanks to the multi-master capabili-
ties of the I2C protocol.
Some I2C interfaces are available:
Interface Description
pcf Philips PCF8584 master/slave interface
iicbb generic bit-banging master-only driver
lpbb parallel port specific bit-banging interface
bktr Brooktree848 video chipset, hardware and software master-only interface
SEE ALSO iicbb(4), lpbb(4), pcf(4)HISTORY
The iicbus manual page first appeared in FreeBSD 3.0.
AUTHORS
This manual page was written by Nicolas Souchu.
BSD August 6, 1998 BSD