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UM10360_0
© NXP B.V. 2009. All rights reserved.
User manual
Rev. 00.06 — 5 June 2009
424 of 808
NXP Semiconductors
UM10360
Chapter 19: LPC17xx I2C0/1/2 interface
The upper 7 bits are the address to which the I
2
C block will respond when addressed by a
master. If the LSB (GC) is set, the I
2
C block will respond to the General Call address
(0x00); otherwise it ignores the General Call address.
The I
2
C-bus rate settings do not affect the I
2
C block in the slave mode. I2EN must be set
to logic 1 to enable the I
2
C block. The AA bit must be set to enable the I
2
C block to
acknowledge its own slave address or the General Call address. STA, STO, and SI must
be reset.
When I2ADR and I2CON have been initialized, the I
2
C block waits until it is addressed by
its own slave address followed by the data direction bit which must be “0” (W) for the I
2
C
block to operate in the slave receiver mode. After its own slave address and the W bit
have been received, the serial interrupt flag (SI) is set and a valid status code can be read
from I2STAT. This status code is used to vector to a state service routine. The appropriate
action to be taken for each of these status codes is detailed in
. The slave
receiver mode may also be entered if arbitration is lost while the I
2
C block is in the master
mode (see status 0x68 and 0x78).
If the AA bit is reset during a transfer, the I
2
C block will return a not acknowledge (logic 1)
to SDA after the next received data byte. While AA is reset, the I
2
C block does not
respond to its own slave address or a General Call address. However, the I
2
C-bus is still
monitored and address recognition may be resumed at any time by setting AA. This
means that the AA bit may be used to temporarily isolate the I
2
C block from the I
2
C-bus.
Table 378. I2CONSET used to initialize Slave Receiver mode
Bit
7
6
5
4
3
2
1
0
Symbol
-
I2EN
STA
STO
SI
AA
-
-
Value
-
1
0
0
0
1
-
-