Nack Reception Transfer Abort Function - Renesas RX100 Series User Manual

RX13T Group
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.
[Master transmit mode]
Automatic low-hold (to prevent wrong transmission)
S
1
SCL0
SDA0
BBSY
Transmit data
(7-bit address + W)
AASy
TRS
TDRE
NACKF
Write data to ICDRT register
(7-bit address + W)
[Slave transmit mode]
S
1 2
SCL0
SDA0
BBSY
AASy
TRS
TDRE
NACKF
Figure 24.31 Abort of Data Transfer When NACK is Received (NACKE = 1)
R01UH0822EJ0100 Rev.1.00
Jul 31, 2019
2 3 4 5 6
7-bit slave address
Transmit data (DATA 1)
Write data to ICDRT
register (DATA 1)
3 4 5 6 7
7-bit slave address
Bus free time (ICBRL)
P S
7 8 9
W A
Transfer
aborted
Transmit data
(7-bit address + W)
Write data to ICDRT register
Write 1 to SP bit
(7-bit address + W)
Clear NACKF flag Write 1 to ST bit
Automatic low-hold
(to prevent wrong transmission)
8 9 1 2 3
W A
Address match
Transmit data (DATA 1)
Write data to ICDRT Write data to ICDRT
register (DATA 1) register (DATA 2)
2
24. I C-bus Interface (RIICa)
1 2 3 4 5 6
7-bit slave address
Transmit data (DATA 1)
Write data to ICDRT
register (DATA 1)
Bus free time
(ICBRL)
4 5 6 7 8
Data (DATA 1)
Transmit data (DATA 2)
Clear NACKF flag
7 8 9
W A
P
9
A
Transfer
aborted
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