© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
User manual
Rev. 01 — 15 August 2005
134
Philips Semiconductors
UM10139
Volume 1
Chapter 11: I
2
C interfaces
for F/S-mode I
2
C-bus devices" in the microcontrollers datasheet). This is sometimes a
useful capability, but intrinsically limits alternate uses for the same pins if the I
2
C interface
is not used. Seldom is this capability needed on multiple I
2
C interfaces within the same
microcontroller.
11.4 Pin description
11.5 I
2
C operating modes
In a given application, the I
2
C block may operate as a master, a slave, or both. In the slave
mode, the I
2
C hardware looks for its own slave address and the general call address. If
one of these addresses is detected, an interrupt is requested. If the processor wishes to
become the bus master, the hardware waits until the bus is free before the master mode is
entered so that a possible slave operation is not interrupted. If bus arbitration is lost in the
master mode, the I
2
C block switches to the slave mode immediately and can detect its
own slave address in the same serial transfer.
11.5.1 Master Transmitter mode
In this mode data is transmitted from master to slave. Before the master transmitter mode
can be entered, the I2CONSET register must be initialized as shown in
. I2EN
must be set to 1 to enable the I
2
C function. If the AA bit is 0, the I
2
C interface will not
Fig 24. I
2
C-bus Configuration
OTHER DEVICE
WITH I
2
C
INTERFACE
Pull-up
resisor
OTHER DEVICE
WITH I
2
C
INTERFACE
LPC2141/2/4/6/8
SDA
SCL
I
2
C BUS
SCL
SDA
Pull-up
resisor
Table 132: I
2
C Pin Description
Pin
Type
Description
SDA0,1
Input/Output
I
2
C Serial Data.
SCL0,1
Input/Output
I
2
C Serial Clock.