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UM10316_0
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 00.06 — 17 December 2008
382 of 571
NXP Semiconductors
UM10316
Chapter 23: LPC2xx I2C-interface
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.
Each of the two I
2
C interfaces on the LPC29xx is byte oriented, and has four operating
modes: master transmitter mode, master receiver mode, slave transmitter mode and
slave receiver mode.
5.
Pin description
When connecting to a 5 V I
2
C bus, the internal pull-up resistor must be disabled in the
. The value of the external pull-up resistor influences the
rising edge of the SDA and SCL signals.
For low-frequency applications (< 20 kHz) and short data lines, the internal pull-up is
sufficient to drive the I2C-bus.
6.
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
Fig 93. I
2
C bus configuration
OTHER DEVICE WITH
I
2
C INTERFACE
pull-up
resistor
OTHER DEVICE WITH
I
2
C INTERFACE
LPC29xx
SDA
SCL
I
2
C bus
SCL
SDA
pull-up
resistor
Table 319. I
2
C pin description
Pin
Type
Description
I2C0_SDA, I2C1_SDA
Input/Output
I
2
C Serial Data.
I2C0_SCL, I2C1_SCL
Input/Output
I
2
C Serial Clock.