R01UH0822EJ0100 Rev.1.00
Page 782 of 1041
Jul 31, 2019
RX13T Group
24. I
2
C-bus Interface (RIICa)
24.8.2
NACK Reception Transfer Abort Function
The RIIC has a function to abort transfer operation when NACK is received in transmit mode (ICCR2.TRS bit is 1). This
function is enabled when the ICFER.NACKE bit is set to 1 (transfer abort enabled). If the next transmit data has already
been written (ICSR2.TDRE flag is 0) when NACK is received, next data transmission at the falling edge of the ninth
SCL clock cycle is automatically aborted. This prevents the SDA0 line output level from being held low when the MSB
of the next transmit data is 0.
If the transfer operation is aborted by this function (ICSR2.NACKF flag is 1), transmit operation and receive operation
are discontinued. To restore transmit/receive operation, be sure to set the NACKF flag to 0. In master transmit mode,
after setting the NACKF flag to 0, issue a restart condition, or issue a stop condition and then issue a start condition
again.
Figure 24.31
Abort of Data Transfer When NACK is Received (NACKE = 1)
1
2
3
4
5
6
7
8
9
2
3
4
5
6
7
8
9
1
W
A
W
A
7-bit slave address
7-bit slave address
S
P
S
BBSY
AASy
TRS
TDRE
NACKF
Automatic low-hold (to prevent wrong transmission)
[Master transmit mode]
Write data to ICDRT register
(7-bit a W)
Write data to ICDRT
register (DATA 1)
Transmit data
(7-bit a W)
Transmit data (DATA 1)
Transfer
aborted
Bus free time (ICBRL)
Write 1 to SP bit
Clear NACKF flag
Write 1 to ST bit
Write data to ICDRT register
(7-bit a W)
Write data to ICDRT
register (DATA 1)
Transmit data (DATA 1)
Transmit data
(7-bit a W)
[Slave transmit mode]
1
2
3
4
5
6
7
8
9
2
3
4
5
6
7
8
9
1
W
A
A
7-bit slave address
Data (DATA 1)
S
P
BBSY
AASy
TRS
TDRE
NACKF
Write data to ICDRT
register (DATA 1)
Transfer
aborted
Clear NACKF flag
Transmit data (DATA 1)
Transmit data (DATA 2)
Address match
Write data to ICDRT
register (DATA 2)
Automatic low-hold
(to prevent wrong transmission)
Bus free time
(ICBRL)
SCL0
SDA0
SCL0
SDA0