UM10375 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2011. All rights reserved.
User manual Rev. 3 — 14 June 2011 220 of 368
NXP Semiconductors
UM10375
Chapter 13: LPC13xx I2C-bus controller
mode. After the address and direction bit have been received, the SI bit is set and a valid
status code can be read from the Status register (I2STAT). Refer to Table 237
for the
status codes and actions.
13.9.4 Slave Transmitter mode
The first byte is received and handled as in the slave receiver mode. However, in this
mode, the direction bit will be 1, indicating a read operation. Serial data is transmitted via
SDA while the serial clock is input through SCL. START and STOP conditions are
recognized as the beginning and end of a serial transfer. In a given application, I
2
C may
operate as a master and as a slave. 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. When the microcontrollers 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 action is not interrupted. If bus arbitration is lost in the master mode, the I
2
C
interface switches to the slave mode immediately and can detect its own slave address in
the same serial transfer.
13.10 I
2
C implementation and operation
Figure 31 shows how the on-chip I
2
C-bus interface is implemented, and the following text
describes the individual blocks.
Fig 29. Format of Slave Receiver mode
A
A = Acknowledge (SDA low)
A = Not acknowledge (SDA high)
S = START condition
P = STOP condition
RS = Repeated START condition
A
A/A
data transferred
(n Bytes + Acknowledge)
“0” - write
“1” - read
from Master to Slave
from Slave to Master
S SLAVE ADDRESS W DATA P/RSDATA
Fig 30. Format of Slave Transmitter mode
DATA
A = Acknowledge (SDA low)
A = Not acknowledge (SDA high)
S = START condition
P = STOP condition
A DATA
data transferred
(n Bytes + Acknowledge)
“0” - write
“1” - read
from Master to Slave
from Slave to Master
S SLAVE ADDRESS R A P
A
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