RX610 Group
22. I
2
C Bus Interface (RIIC)
R01UH0032EJ0120 Rev.1.20
Page 694 of 1006
Feb 20, 2013
Note: If an internal reset is initiated using the IICRST bit for a bus hang-up occurred during communication with the
master device in slave mode, the states may become different between the slave device and the master device
(due to the difference in the bit counter information). For this reason, do not initiate an internal reset in slave
mode, but initiate restoration processing from the master device. If an internal reset is necessary because the RIIC
hangs up with the SCLn line in a low level output state in slave mode, initiate an internal reset and then issue a
restart condition from the master device or resume communication from the start condition issuance after issuing
a stop condition. If communication is restarted by initiating a reset solely in the slave device without issuing a
start condition or restart condition from the master device, synchronization will be lost because the master and
slave devices operate asynchronously.
Table 22.4 RIIC Resets
IICRST
ICE
State
Specifications
1
0
RIIC reset
Resets all registers and internal states of the RIIC.
1
Internal reset
Reset the BC[2:0] bits in ICMR1, and the ICSR1, ICSR2, ICDRS registers and the
internal states of the RIIC.
ICE Bit (I
2
C Bus Interface Enable)
This bit is used to enable or disable the transfer operation of the RIIC.
When this bit is set to 0 to disable the RIIC, the SCLn pin and SDAn pin function as ports. An RIIC reset is initiated by
setting the IICRST bit to 1 with the ICE bit set to 0, and an internal reset is initiated by setting the IICRST bit to 1 with
the ICE bit set to 1.
To prevent unexpected communications, set the RIIC registers with the ICE bit set to 0 (to disable the RIIC), and set the
ICE bit to 1 (to enable the transfer operation) after finishing all register settings.
Note: In addition to the I
2
C bus pin functions, other functions are also multiplexed onto the pins of the RX610 Group.
To use the pins as I
2
C bus pins (SCLn pin and SDAn pin), disable the other multiplexed functions. Since both of
the SCLn pin and SDAn pin of the I
2
C bus pins are I/O pins, set the corresponding Pn.DDR register to 0 (input)
and set the Pn.ICR register to 1 (input buffer enabled).