SWCU195A December 2024 – May 2025 CC2744R7-Q1 , CC2745P10-Q1 , CC2745R10-Q1 , CC2745R7-Q1 , CC2755R10
The M_CAN can be set in External Loop Back Mode by programming TEST.LBCK to one. In Loop Back Mode, the M_CAN treats its own transmitted messages as received messages and stores them (if they pass acceptance filtering) into an Rx Buffer or an Rx FIFO. Figure 5 shows the connection of signals m_can_tx and m_can_rx to the M_CAN in External Loop Back Mode.
This mode is provided for hardware self-test. To be independent from external stimulation, the M_CAN ignores acknowledge errors (recessive bit sampled in the acknowledge slot of a data/remote frame) in Loop Back Mode. In this mode the M_CAN performs an internal feedback from its Tx output to its Rx input. The actual value of the m_can_rx input pin is disregarded by the M_CAN. The transmitted messages can be monitored at the m_can_tx pin.