I2C Client Drivers

The I2C bus, invented by Philips (now NXP) is a two-wire, Serial Data (SDA), Serial Clock (SCL) asynchronous serial bus. It is a multi-master bus, though multi-master mode is not widely used. Both SDA and SCL are open drain/open collector, meaning that each of these can drive its output low, but neither of them can drive its output high without having pull-up resistors. SCL is generated by the master in order to synchronize data transfer (carried by SDA) over the bus. Both slave and master can send data (not at the same time of course), thus making SDA a bidirectional line. That said, the SCL signal is also bidirectional, since the slave can stretch the clock by keeping the SCL line low. The bus is controlled by the master, which in our case is a part of the SoC. This bus is frequently used in embedded systems to connect serial EEPROM, RTC chips...