EFM32WG Datasheet, PDF (427/834 Pages) List of Unclassifed Manufacturers – The EFM32WG Wonder Gecko is the ideal choice for demanding 8-, 16-, and 32-bit energy sensitive applications.

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until room is available in the shift register. Transmission then continues and the address is loaded into
the shift register. If this address does not pass address recognition, it is automatically NACK’ed by the
slave, and the slave goes to an idle state. The address byte is in this case discarded, making the shift
register ready for a new address. It is not loaded into the receive buffer.
If the address was accepted and the R/W bit was set (R), indicating that the master wishes to read from
the slave, the slave now goes into the slave transmitter mode. Software interaction is now required to
decide whether the slave wants to acknowledge the request or not. The accepted address byte is loaded
into the receive buffer like a regular data byte. If no valid interaction is pending, the bus is held until the
slave responds with a command. The slave can reject the request with a single NACK command.
The slave will in that case go to an idle state, and wait for the next start condition. To continue the
transmission, the slave must make sure data is loaded into the transmit buffer and send an ACK. The
loaded data will then be transmitted to the master, and an ACK or NACK will be received from the master.
Data transmission can also continue after a NACK if a CONT command is issued along with the NACK.
This is not standard I²C however.
If the master responds with an ACK, it may expect another byte of data, and data should be made
available in the transmit buffer. If data is not available, the bus is held until data is available.
If the response is a NACK however, this is an indication of that the master has received enough bytes
and wishes to end the transmission. The slave now automatically goes idle, unless CONT in I2Cn_CMD
is set and data is available for transmission. The latter is not standard I²C.
The master ends the transmission by sending a STOP or a repeated START. The SSTOP interrupt
flag in I2Cn_IF is set when the master transmits a STOP condition. If the transmission is ended with a
repeated START, then the SSTOP interrupt flag is not set.
Note
The SSTOP interrupt flag in I2Cn_IF will be set regardless of whether the slave is
participating in the transmission or not, as long as SLAVE in I2Cn_CTRL is set and a STOP
condition is detected
If arbitration is lost at any time during transmission, the ARBLOST interrupt flag in I2Cn_IF is set, the
bus is released and the slave goes idle.
See Table 16.8 (p. 428) for more information.
2013-05-08 - Wonder Gecko Family - d0233_Rev0.50
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