Chapter 14 Serial Communication Interface (S12SCIV6)MC9S12ZVMB Family Reference Manual Rev. 1.3502 NXP Semiconductors14.4.5.5 LIN Transmit Collision DetectionThis module allows to check for collisions on the LIN bus.Figure 14-18. Collision Detect PrincipleIf the bit error circuit is enabled (BERRM[1:0] = 0:1 or = 1:0]), the error detect circuit will compare thetransmitted and the received data stream at a point in time and flag any mismatch. The timing checks runwhen transmitter is active (not idle). As soon as a mismatch between the transmitted data and the receiveddata is detected the following happens:• The next bit transmitted will have a high level (TXPOL = 0) or low level (TXPOL = 1)• The transmission is aborted and the byte in transmit buffer is discarded.• the transmit data register empty and the transmission complete flag will be set• The bit error interrupt flag, BERRIF, will be set.• No further transmissions will take place until the BERRIF is cleared.Figure 14-19. Timing Diagram Bit Error DetectionIf the bit error detect feature is disabled, the bit error interrupt flag is cleared.NOTEThe RXPOL and TXPOL bit should be set the same when transmissioncollision detect feature is enabled, otherwise the bit error interrupt flag maybe set incorrectly.TXD PinRXD PinLIN Physical InterfaceSynchronizer StageBus ClockReceive ShiftRegisterTransmit ShiftRegisterLIN BusCompareSampleBit ErrorPointOutput TransmitShift Register0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 0Input ReceiveShift RegisterBERRM[1:0] = 0:1 BERRM[1:0] = 1:1Compare Sample PointsSampling BeginSampling BeginSampling EndSampling End
