4.1 2-Wire Standard Mode I2C Protocol Compatible Interface

The MCP9808 Serial Clock (SCL) input and the bidirectional Serial Data (SDA) line form a 2-wire bidirectional, Standard mode, I2C compatible communication port (refer to the Table 1-2 and Table 1-4 tables).

The following bus protocol has been defined:

Table 4-1. MCP9808 Serial Bus Protocol Descriptions
TermDescription
MasterThe device that controls the serial bus, typically a microcontroller.
SlaveThe device addressed by the master, such as the MCP9808.
TransmitterDevice sending data to the bus.
ReceiverDevice receiving data from the bus.
STARTA unique signal from the master to 
initiate serial interface with a slave.
STOPA unique signal from the master to terminate serial interface from a slave.
Read/WriteA read or write to the MCP9808 registers.
ACKA receiver Acknowledges (ACK) the reception of each byte by polling the bus.
NAKA receiver Not-Acknowledges (NAK) or releases the bus to show End-of-Data (EOD).
BusyCommunication is not possible because the bus is in use.
Not BusyThe bus is in the Idle state; both SDA and SCL remain high.
Data ValidSDA must remain stable before SCL becomes high in order for a data bit to be considered valid. During normal data transfers, SDA only changes state while SCL is low.