RX610 Group
22. I
2
C Bus Interface (RIIC)
R01UH0032EJ0120 Rev.1.20
Page 754 of 1006
Feb 20, 2013
22.8.2
NACK Reception Transfer Suspension Function
The RIIC has a function to suspend transfer operation when NACK is received in transmit mode (TRS bit = 1 in ICCR2).
This function is enabled when the NACKE bit in ICFER is set to 1 (transfer suspension enabled). If the next transmit data
has already been written (TDRE flag = 0 in ICSR2) when NACK is received, next data transmission at the falling edge of
the ninth SCL clock cycle is automatically suspended. This prevents the SDAn line output level from being held low
when the MSB of the next transmit data is 0.
If the transfer operation is suspended by this function (NACKF flag = 1 in ICSR2), transmit operation and receive
operation are discontinued. To restore transmit/receive operation, be sure to clear the NACKF flag to 0. In master
transmit mode, clear the NACKF flag to 0, issue a restart or stop condition, and then issue a start condition again.
ACK
NACK
ACK
Transfer suspended
Transmit data (DATA2)
Write data to ICDRT
(7-bit a W)
TDRE
AASn
TRS
BBSY
NACKF
S
1
2
3
4
5
6
7
2
3
4
5
6
7
8
9
[Master transmit mode]
[Slave transmit mode]
TDRE
AASn
TRS
BBSY
NACKF
S
2
3
4
5
6
7
8
W
9
S
2
3
4
5
6
7
8
W
9
8
W
9
P
P
SCLn
SDAn
SCLn
SDAn
Dummy read ICDRR
1
1
1
Automatic low-hold (to prevent wrong transmission)
Bus free time (ICBRL)
7-bit slave address
7-bit slave address
Write data to ICDRT
(DATA1)
Write data to ICDRT
(7-bit a W)
Write data to ICDRT
(DATA1)
Clear NACKF
Clear NACKF
Write data to ICDRT
(DATA1)
Write data to ICDRT
(DATA2)
Automatic low-hold (to prevent wrong transmission)
Bus free time
(ICBRL)
7-bit slave address
Data (DATA1)
Transmit data
(7-bit a W)
Transmit data (DATA1)
Transmit data
(7-bit a W)
Transmit data (DATA1)
Transfer suspended
Transmit data (DATA1)
Address match
Write 1 to SP
Write 1 to SP
Figure 22.30 Suspension of Data Transfer when NACK is Received (NACKE = 1)