SWRU543B January 2019 – June 2025 CC3230S , CC3230SF , CC3235MODS , CC3235MODSF , CC3235S , CC3235SF
The I2C bus uses only two signals: SDA and SCL, named I2CSDA and I2CSCL on CC32xx microcontrollers. SDA is the bidirectional serial data line and SCL is the bidirectional serial clock line. The bus is considered idle when both lines are high.
Every transaction on the I2C bus is 9 bits long, consisting of 8 data bits and 1 acknowledge bit. The number of bytes per transfer (defined as the time between a valid START and STOP condition, described in Section 7.2.1.1) is unrestricted, but each data byte must be followed by an acknowledge bit, and data must be transferred to MSB first. When a receiver cannot receive another complete byte, the receiver holds the clock line SCL low and forces the transmitter into a wait state. The data transfer continues when the receiver releases the clock SCL.