UM10237_2 © NXP B.V. 2008. All rights reserved.
User manual Rev. 02 — 19 December 2008 576 o f 792
NXP Semiconductors UM10237
Chapter 22: LPC24XX I2C interfaces I2C0/1/2
6.3 Slave Receiver mode
In the slave receiver mode, data bytes are received from a master transmitter. To initialize
the slave receiver mode, user write the Slave Address Register (I2ADR) and write the I2C
Control Set Register (I2CONSET) as shown in Table22–511.
I2EN must be set to 1 to enable the I2C function. AA bit must be set to 1 to acknowledge
its own slave address or the general call address. The STA, STO and SI bits are set to 0.
After I2ADR and I2CONSET are initialized, the I2C interface waits until it is addressed by
its own address or general address followed by the data direction bit. If the direction bit is
0 (W), it enters slave receiver mode. If the direction bit is 1 (R), it enters slave tra nsmitter
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 (I2STA T). Refer to Table 22–527 for the
status codes and actions.
Fig 114. A master receiver switch to master Transmitter after sending repeated START
A = Acknowledge (SDA low)
A = Not acknowledge (SDA high)
S = START condition
P = STOP condition
SLA = Slave Address
DATA
data transferred
(n Bytes + Acknowledge)
From master to slave
From slave to master
A DATA A ASLA R RS W PS SLA DATAAA
Table 511. I2CnC ONSET used to configure Slave mode
Bit 7 6 5 4 3 2 1 0
Symbol - I2EN STA STO SI AA - -
Value- 10001--
Fig 115. 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
AA/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