SBOS571C August 2011 – August 2018 BUF20800-Q1
The BUF20800-Q1 communicates through an industry standard, two-wire interface to receive data in slave mode. This standard uses a two-wire, open-drain interface that supports multiple devices on a single bus. Bus lines are driven to a logic low level only. The device that initiates the communication is called a master, and the devices controlled by the master are slaves. The master generates the serial clock on the clock signal line (SCL), controls the bus access, and generates the START and STOP conditions.
To address a specific device, the master initiates a START condition by pulling the data signal line (SDA) from a HIGH to a LOW logic level while SCL is HIGH. All slaves on the bus shift in the slave address byte, with the last bit indicating whether a read or write operation is intended. During the 9th clock pulse, the slave being addressed responds to the master by generating an Acknowledge and pulling SDA LOW.
Data transfer is then initiated and eight bits of data are sent followed by an Acknowledge Bit. During data transfer, SDA must remain stable while SCL is HIGH. Any change in SDA while SCL is HIGH will be interpreted as a START or STOP condition.
Once all data has been transferred, the master generates a STOP condition indicated by pulling SDA from LOW to HIGH while SCL is HIGH.
The BUF20800-Q1 can act only as a slave device; therefore, it never drives SCL. SCL is only an input for the BUF20800-Q1. Table 1 and Table 2 summarize the address and command codes, respectively, for the BUF20800-Q1.