MS51
Nov. 28, 2019
Page
114
of 491
Rev 1.00
MS51
32K
SE
RIES
TE
CHNICAL RE
F
EREN
CE MA
N
UAL
Bit
Name
Description
2
AA
Acknowledge assert flag
If the AA flag is set, an ACK (low level on I2C0_SDA) will be returned during the acknowledge clock
pulse of the I2C0_SCL line while the I
2
C device is a receiver or an own-address-matching slave.
If the AA flag is cleared, a NACK (high level on I2C0_SDA) will be returned during the acknowledge
clock pulse of the I2C0_SCL line while the I
2
C device is a receiver or an own-address-matching
slave. A device with its own AA flag cleared will ignore its own salve address and the General Call.
Consequently, SI will note be asserted and no interrupt is requested.
Note that if an addressed slave does not return an ACK under slave receiver mode or not receive
an ACK under slave transmitter mode, the slave device will become a not addressed slave. It
cannot receive any data until its AA flag is set and a master addresses it again.
There is a special case of I2STAT value C8H occurs under slave transmitter mode. Before the slave
device transmit the last data byte to the master, AA flag can be cleared as 0. Then after the last
data byte transmitted, the slave device will actively switch to not addressed slave mode of
disconnecting with the master. The further reading by the master will be all FFH.
0
I2CPX
I
2
C pins select
0 = Assign I2C0_SCL to P1.3 and I2C0_SDA to P1.4.
1 = Assign I2C0_SCL to P0.2 and I2C0_SDA to P1.6.
Note that I
2
C pins will exchange immediately once setting or clearing this bit.