SLAU893B October 2023 – July 2024 MSPM0C1103 , MSPM0C1103-Q1 , MSPM0C1104 , MSPM0C1104-Q1
A controller can start a transfer only if the bus is idle. It's possible for two or more controllers to generate a START condition within minimum hold time of the START condition. In these situations, an arbitration scheme takes place on the SDA line, while SCL is high (see Figure 13-8) . The first controller transmitter that generates a logic high is overruled by the opposing controller generating a logic low and the losing controller releases the bus until the bus is idle again.
Arbitration can take place over several bits. Its first stage is a comparison of address bits, and if both controllers are trying to address the same device, arbitration continues on to the comparison of data bits.
When an arbitration lost is detected the I2Cx.MSR.ARBLST flag is set. It will be reset by the hardware with the next STOP condition detected on the bus. Additionally the ARBLOST flags in CPU_INT.RIS registers are set.
If arbitration is lost when the I2C controller has initiated a transfer, the application should execute the following steps to correctly handle the arbitration loss: