Internal Loop Back mode is entered by setting bits MCAN_TEST.LBCK and MCAN_CCCR.MON. This mode can be used for a “Hot Selftest”, meaning the MCAN can be tested without affecting a running CAN system connected to the pins CANTX and CANRX. In this mode, pin CANRX is disconnected from the MCAN, and pin CANTX is held recessive. The figure below shows the connection of CANTX and CANRX to the MCAN when Internal Loop Back mode is enabled.
Figure 1. Pin Control in Loop Back Modes
