© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
User manual
Rev. 01 — 15 August 2005
133
11.1 Features
•
Standard I
2
C compliant bus interfaces that may be configured as Master, Slave, or
Master/Slave.
•
Arbitration between simultaneously transmitting masters without corruption of serial
data on the bus.
•
Programmable clock to allow adjustment of I
2
C transfer rates.
•
Bidirectional data transfer between masters and slaves.
•
Serial clock synchronization allows devices with different bit rates to communicate via
one serial bus.
•
Serial clock synchronization can be used as a handshake mechanism to suspend and
resume serial transfer.
•
The I
2
C-bus may be used for test and diagnostic purposes.
11.2 Applications
Interfaces to external I
2
C standard parts, such as serial RAMs, LCDs, tone generators,
etc.
11.3 Description
A typical I
2
C-bus configuration is shown in
. Depending on the state of the
direction bit (R/W), two types of data transfers are possible on the I
2
C-bus:
•
Data transfer from a master transmitter to a slave receiver. The first byte transmitted
by the master is the slave address. Next follows a number of data bytes. The slave
returns an acknowledge bit after each received byte.
•
Data transfer from a slave transmitter to a master receiver. The first byte (the slave
address) is transmitted by the master. The slave then returns an acknowledge bit.
Next follows the data bytes transmitted by the slave to the master. The master returns
an acknowledge bit after all received bytes other than the last byte. At the end of the
last received byte, a “not acknowledge” is returned. The master device generates all
of the serial clock pulses and the START and STOP conditions. A transfer is ended
with a STOP condition or with a repeated START condition. Since a repeated START
condition is also the beginning of the next serial transfer, the I
2
C-bus will not be
released.
The LPC2141/2/4/6/8 I
2
C interfaces are byte oriented, and have four operating modes:
master transmitter mode, master receiver mode, slave transmitter mode and slave
receiver mode.
The I
2
C interfaces compile with entire I
2
C specification, supporting the ability to turn
power off to the LPC2141/2/4/6/8 without causing a problem with other devices on the
same I
2
C-bus (see "The I
2
C-bus specification" description under the heading
"Fast-Mode", and notes for the table titled "Characteristics of the SDA and SCL I/O stages
UM10139
Chapter 11: I
2
C interfaces I
2
C0 and I
2
C1
Rev. 01 — 15 August 2005
User manual