SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
Entering Bus Monitoring Mode is done by setting the MCAN_CCCR[5] MON bit to 1. In this mode (see ISO 11898-1:2015, Bus Monitoring section), the MCAN module is able to receive valid data and remote frames, but cannot start a transmission. The MCAN module sends only recessive bits on the CAN bus. If the MCAN module is required to send a dominant bit (ACK bit, overload flag, active error flag), the bit is rerouted internally so that the MCAN module monitors this dominant bit, although the CAN bus may remain in recessive state. In Bus Monitoring Mode the MCAN_TXBRP register 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 26-192 shows the connection of the MCAN_TX and MCAN_RX signals to the MCAN module in Bus Monitoring Mode.