RX610 Group
22. I
2
C Bus Interface (RIIC)
R01UH0032EJ0120 Rev.1.20
Page 725 of 1006
Feb 20, 2013
22.2.15 I
2
C Bus Transmit Data Register (ICDRT)
Addresses: RIIC0.ICDRT 0008 8312h, RIIC1.ICDRT 0008 8332h
b7
b6
b5
b4
b3
b2
b1
b0
Value after reset:
1
1
1
1
1
1
1
1
ICDRT is an 8-bit readable/writable register that stores transmit data. When ICDRT detects a space in the I
2
C bus shift
register (ICDRS), it transfers the transmit data that has been written to ICDRT to ICDRS and starts transmitting data in
transmit mode.
The double-buffer structure of ICDRT and ICDRS allows continuous transmit operation if the next transmit data has
been written to ICDRT while the ICDRS data is being transmitted.
ICDRT can always be read and written. Write transmit data to ICDRT once when a transmit data empty interrupt
(ICTXI) request is generated.
22.2.16 I
2
C Bus Receive Data Register (ICDRR)
Addresses: RIIC0.ICDRR 0008 8313h, RIIC1.ICDRR 0008 8333h
b7
b6
b5
b4
b3
b2
b1
b0
Value after reset:
0
0
0
0
0
0
0
0
ICDRR is an 8-bit read-only register that stores receive data. When one byte of data has been received, the received data
is transferred from the I
2
C bus shift register (ICDRS) to ICDRR to enable the next data to be received.
The double-buffer structure of ICDRS and ICDRR allows continuous receive operation if the received data has been read
from ICDRR while ICDRS is receiving data.
ICDRR cannot be written. Read data from ICDRR once when a receive data full interrupt (ICRXI) request is generated.
If ICDRR receives the next receive data before the current data is read from ICDRR (while the RDRF flag in ICSR2 is 1),
the RIIC automatically holds the SCL clock low one cycle before the RDRF flag is set to 1 next.
22.2.17 I
2
C Bus Shift Register (ICDRS)
b7
b6
b5
b4
b3
b2
b1
b0
Value after reset:
—
—
—
—
—
—
—
—
—
ICDRS is an 8-bit shift register to transmit and receive data.
During transmission, transmit data is transferred from ICDRT to ICDRS and is sent from the SDAn pin. During reception,
data is transferred from ICDRS to ICDRR after one byte of data has been received.
ICDRS cannot be accessed directly.