DocID018909 Rev 11 849/1731
RM0090 Inter-integrated circuit (I
2
C) interface
864
be set before the ACK of the CRC reception in slave mode. It must be set when
the ACK is set low in master mode.
• A PECERR error flag/interrupt is also available in the I2C_SR1 register.
• If DMA and PEC calculation are both enabled:-
– In transmission: when the I
2
C interface receives an EOT signal from the DMA
controller, it automatically sends a PEC after the last byte.
– In reception: when the I
2
C interface receives an EOT_1 signal from the DMA
controller, it will automatically consider the next byte as a PEC and will check it. A
DMA request is generated after PEC reception.
• To allow intermediate PEC transfers, a control bit is available in the I2C_CR2 register
(LAST bit) to determine if it is really the last DMA transfer or not. If it is the last DMA
request for a master receiver, a NACK is automatically sent after the last received byte.
• PEC calculation is corrupted by an arbitration loss.
27.4 I
2
C interrupts
The table below gives the list of I
2
C interrupt requests.
Note: SB, ADDR, ADD10, STOPF, BTF, RxNE and TxE are logically ORed on the same interrupt
channel.
BERR, ARLO, AF, OVR, PECERR, TIMEOUT and SMBALERT are logically ORed on the
same interrupt channel.
Table 123. I
2
C Interrupt requests
Interrupt event Event flag Enable control bit
Start bit sent (Master) SB
ITEVFEN
Address sent (Master) or Address matched (Slave) ADDR
10-bit header sent (Master) ADD10
Stop received (Slave) STOPF
Data byte transfer finished BTF
Receive buffer not empty RxNE
ITEVFEN and ITBUFEN
Transmit buffer empty TxE
Bus error BERR
ITERREN
Arbitration loss (Master) ARLO
Acknowledge failure AF
Overrun/Underrun OVR
PEC error PECERR
Timeout/Tlow error TIMEOUT
SMBus Alert SMBALERT
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