SPRUJ79 November 2024 F29H850TU , F29H859TU-Q1
If two or more controller-transmitters attempt to start a transmission on the same bus at approximately the same time, an arbitration procedure is invoked. The arbitration procedure uses the data presented on the serial data bus (SDA) by the competing transmitters. Figure 37-17 illustrates the arbitration procedure between two devices. The first controller-transmitter that releases the SDA line high is overruled by another controller-transmitter that drives the SDA low. The arbitration procedure gives priority to the device that transmits the serial data stream with the lowest binary value. If two or more devices send identical first bytes, arbitration continues on the subsequent bytes.
If the I2C module is the losing controller, the I2c module switches to the target-receiver mode, sets the arbitration lost (ARBL) flag, and generates the arbitration-lost interrupt request.
If during a serial transfer the arbitration procedure is still in progress when a repeated START condition or a STOP condition is transmitted to SDA, the controller-transmitters involved must send the repeated START condition or the STOP condition at the same position in the format frame. Arbitration is not allowed between: