Nack Reception Transfer Suspension Function - Renesas RZ/A Series User Manual

RZ/A1L Group, RZ/A1LU Group, RZ/A1LC Group
18.10.2

NACK Reception Transfer Suspension Function

The RIIC has a function to suspend transfer operation when NACK is received in transmit mode
(RIICnCR2.TRS bit = 1). This function is enabled when the RIICnFER.NACKE bit is set to 1 (transfer
suspension enabled). If the next transmit data has already been written (RIICnSR2.TDRE flag = 0)
when NACK is received, next data transmission at the falling edge of the ninth SCL clock cycle is
automatically suspended. This prevents the SDA 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 (RIICnSR2.NACKF flag = 1), 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 after issuing a restart condition
or clear the NACKF and STOP flags to 0 after confirming that a stop condition has been issued, and
then issue a start condition.
[Master transmit mode]
SCLn
SDAn
BBSY
AASy
TRS
TDRE
NACKF
[Slave transmit mode]
SCLn
SDAn
BBSY
AASy
TRS
TDRE
NACKF
Figure 18.31
R01UH0437EJ0600 Rev.6.00
Jan 29, 2021
Automatic low-hold (to prevent wrong transmission)
S 1 2 3 4 5
7-bit slave address
Transmit data
Transmit data (DATA 1)
(7-bit address + W)
Write data to Write data to RIICnDRT
RIICnDRT (DATA 1)
(7-bit address + W)
S 1 2 3 4 5 6
7-bit slave address
Suspension of Data Transfer when NACK is Received (NACKE = 1)
Write 1 to SP
6 7 8 9 P
W NACK
Transfer suspended
Clear NACKF Write data to
RIICnDRT
(7-bit address + W)
Automatic low-hold (to prevent wrong transmission)
7 8 9 1 2 3
Data (DATA 1)
W ACK
Address match
Transmit data (DATA 1)
Write data to RIICnDRT Write data to RIICnDRT
(DATA 1) (DATA 2)
18. I²C Bus Interface
Bus free time (RIICnBRL)
S 1 2 3 4 5 6
7-bit slave address
Transmit data
Transmit data (DATA 1)
(7-bit address + W)
Write data to
RIICnDRT
(DATA 1)
4 5 6 7 8 9 P
Transfer suspended
Transmit data (DATA 2)
7 8 9
W ACK
Bus free time
(RIICnBRL)
Clear NACKF
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