SWCU185G January 2018 – June 2024 CC1312PSIP , CC1312R , CC1352P , CC1352R , CC2642R , CC2642R-Q1 , CC2652P , CC2652PSIP , CC2652R , CC2652RB , CC2652RSIP , CC2662R-Q1
The I2C bus uses only two signals: SDA and SCL, named I2CSDA and I2CSCL on the CC13x2 and CC26x2 controllers. SDA is the bidirectional serial data line and SCL line 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 24.3.1.1) is unrestricted, an acknowledge bit must follow each byte, and data must be transferred by the MSB first. When a receiver cannot receive another complete byte, the receiver can hold the clock line SCL low and force the transmitter into a wait state. The data transfer continues when the receiver releases the clock SCL.