SWCU195A December 2024 – May 2025 CC2744R7-Q1 , CC2745P10-Q1 , CC2745R10-Q1 , CC2745R7-Q1 , CC2755R10
The M_CAN is set in Bus Monitoring Mode by programming CCCR.MON to one. In Bus Monitoring Mode (see ISO 11898-1:2015, 10.14 Bus monitoring), the M_CAN is able to receive valid data frames and valid remote frames, but cannot start a transmission. In this mode, it sends only recessive bits on the CAN bus. If the M_CAN is required to send a dominant bit (ACK bit, overload flag, active error flag), the bit is rerouted internally so that the M_CAN monitors this dominant bit, although the CAN bus may remain in recessive state. In Bus Monitoring Mode register TXBRP is held in reset state.
The Bus Monitoring Mode can be used to analyze the traffic on a CAN bus without affecting it by the transmission of dominant bits. Figure 5 shows the connection of signals m_can_tx and m_can_rx to the M_CAN in Bus Monitoring Mode.