RM0091 Inter-integrated circuit (I
2
C) interface
Doc ID 018940 Rev 1 481/742
Note: The SBC bit must be configured when the I2C is disabled, or when the slave is not
addressed, or when ADDR=1.
The RELOAD bit value can be changed when ADDR=1, or when TCR=1.
Caution: Slave Byte Control mode is not compatible with NOSTRETCH mode. Setting SBC when
NOSTRETCH=1 is not allowed.
Figure 202. Slave initialization flowchart.
Slave transmitter
A transmit interrupt status (TXIS) is generated when the I2Cx_TXDR register becomes
empty. An interrupt is generated if the TXIE bit is set in the I2Cx_CR1 register.
The TXIS bit is cleared when the I2Cx_TXDR register is written with the next data byte to be
transmitted.
When a NACK is received, the NACKF bit is set in the I2Cx_ISR register and an interrupt is
generated if the NACKIE bit is set in the I2Cx_CR1 register. The slave automatically
releases the SCL and SDA lines in order to let the master perform a STOP or a RESTART
condition. The TXIS bit is not set when a NACK is received.
MS19850V1
Initial settings
Slave
initialization
Clear {OA1EN, OA2EN} in I2Cx_CR1
Configure {OA1[9:0], OA1MODE, OA1EN,
OA2[6:0], OA2MSK[2:0], OA2EN, GCEN}
Configure SBC in I2Cx_CR1*
Enable interrupts and/or
DMA in I2Cx_CR1
End
*SBC must be set to support SMBus features
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