SLAU367P October 2012 – April 2020 MSP430FR5041 , MSP430FR5043 , MSP430FR50431 , MSP430FR5847 , MSP430FR58471 , MSP430FR5848 , MSP430FR5849 , MSP430FR5857 , MSP430FR5858 , MSP430FR5859 , MSP430FR5867 , MSP430FR58671 , MSP430FR5868 , MSP430FR5869 , MSP430FR5870 , MSP430FR5872 , MSP430FR58721 , MSP430FR5887 , MSP430FR5888 , MSP430FR5889 , MSP430FR58891 , MSP430FR5922 , MSP430FR59221 , MSP430FR5947 , MSP430FR59471 , MSP430FR5948 , MSP430FR5949 , MSP430FR5957 , MSP430FR5958 , MSP430FR5959 , MSP430FR5962 , MSP430FR5964 , MSP430FR5967 , MSP430FR5968 , MSP430FR5969 , MSP430FR5969-SP , MSP430FR59691 , MSP430FR5970 , MSP430FR5972 , MSP430FR59721 , MSP430FR5986 , MSP430FR5987 , MSP430FR5988 , MSP430FR5989 , MSP430FR5989-EP , MSP430FR59891 , MSP430FR5992 , MSP430FR5994 , MSP430FR59941 , MSP430FR6005 , MSP430FR6007 , MSP430FR6035 , MSP430FR6037 , MSP430FR60371 , MSP430FR6041 , MSP430FR6043 , MSP430FR60431 , MSP430FR6045 , MSP430FR6047 , MSP430FR60471 , MSP430FR6820 , MSP430FR6822 , MSP430FR68221 , MSP430FR6870 , MSP430FR6872 , MSP430FR68721 , MSP430FR6877 , MSP430FR6879 , MSP430FR68791 , MSP430FR6887 , MSP430FR6888 , MSP430FR6889 , MSP430FR68891 , MSP430FR6920 , MSP430FR6922 , MSP430FR69221 , MSP430FR6927 , MSP430FR69271 , MSP430FR6928 , MSP430FR6970 , MSP430FR6972 , MSP430FR69721 , MSP430FR6977 , MSP430FR6979 , MSP430FR69791 , MSP430FR6987 , MSP430FR6988 , MSP430FR6989 , MSP430FR69891
32.3.5.2.2 I2C Master Receiver Mode
After initialization, master receiver mode is initiated by writing the desired slave address to the UCBxI2CSA register, selecting the size of the slave address with the UCSLA10 bit, clearing UCTR for receiver mode, and setting UCTXSTT to generate a START condition.
The eUSCI_B module checks if the bus is available, generates the START condition, and transmits the slave address. The UCTXSTT flag is cleared as soon as the complete address is sent.
After the acknowledge of the address from the slave, the first data byte from the slave is received and acknowledged and the UCRXIFG flag is set. Data is received from the slave, as long as:
- No automatic STOP is generated
- The UCTXSTP bit is not set
- The UCTXSTT bit is not set
If the slave does not acknowledge the transmitted address, the not-acknowledge interrupt flag UCNACKIFG is set. The master must react with either a STOP condition or a repeated START condition.
A STOP condition is either generated by the automatic STOP generation or by setting the UCTXSTP bit. The next byte received from the slave is followed by a NACK and a STOP condition. This NACK occurs immediately if the eUSCI_B module is currently waiting for UCBxRXBUF to be read.
If a RESTART is sent, UCTR may be set or cleared to configure transmitter or receiver, and a different slave address may be written into UCBxI2CSA if desired.
Figure 32-13 shows the I2C master receiver operation.
NOTE
Consecutive master transactions without repeated START
When performing multiple consecutive I2C master transactions without the repeated START feature, the current transaction must be completed before the next one is initiated. This can be done by ensuring that the transmit STOP condition flag UCTXSTP is cleared before the next I2C transaction is initiated with setting UCTXSTT = 1. Otherwise, the current transaction might be affected.
Figure 32-13 I2C Master Receiver Mode