Regardless of whether the transaction is a read or write, the host must start by sending the
10-bit address with the R/W direction bit set to
‘0’.
The client address match logic supports recognition of 7-bit addresses and General Call Address. The Client Address (TWIn.SADDR) register is used by the client address match logic to determine if a host device has addressed the TWI client.
The TWI client address match logic only supports recognition of the first byte of a 10-bit address, and the second byte must be handled in software. The first byte of the 10-bit address will be recognized if the upper five bits of the Client Address (TWIn.SADDR) register are 0b11110. Thus, the first byte will consist of five indication bits, the two Most Significant bits (MSbs) of the 10-bits address, and the R/W direction bit. The Least Significant Byte (LSB) of the address that follows from the host will come in the form of a data packet.
