Datasheet

Section 17 I
2
C Bus Interface (IIC)
Rev. 3.00 Sep. 28, 2009 Page 528 of 910
REJ09B0350-0300
Bit Bit Name
Initial
Value
R/W Description
0 ACKB 0 R/W
Acknowledge Bit
Stores acknowledge data.
The bit function varies depending on transmit mode
and receive mode.
Transmit mode:
Holds the acknowledge data returned by the receiving
device.
[Setting condition]
When 1 is received as the acknowledge bit when
ACKE = 1 in transmit mode
[Clearing conditions]
• When 0 is received as the acknowledge bit when
ACKE = 1 in transmit mode
• When 0 is written to the ACKE bit
Receive mode:
Sets the acknowledge data to be returned to the
transmitting device.
0: Returns 0 as acknowledge data after data reception
1: Returns 1 as acknowledge data after data reception
When this bit is read, the value loaded from the bus
line (returned by the receiving device) is read in
transmission (when TRS = 1). In reception (when TRS
= 0), the value set by internal software is read.
When this bit is written, acknowledge data that is
returned after receiving is rewritten regardless of the
TRS value.
Note: When, in transmit mode, this bit has been
overwritten by a bit manipulation instruction with a
value other than that of the ACKB flag in ICSR, the
value of the ACKB bit as the acknowledge data setting
for receive mode is overwritten by this value. Thus,
always reset the acknowledge data when switching to
receive mode.
Write 0 to the ACKE bit to clear the ACKB flag to 0 in
the following cases:
in master mode—before transmission is ended and a
stop condition is generated; and
in slave mode—before transmission is ended and SDA
is released to allow a master device to issue a stop
condition.
Note: * Only 0 can be written to clear the flag.