Loopback mode is used for diagnostic purposes. When in loopback mode, the controller must only be programmed to enter configuration mode or issue a reset. In loop back mode, the following actions occur.
•The controller transmits a recessive bitstream onto the CAN_PHY_TX bus signal.
•TX messages are internally looped back to the RX line and are acknowledged.
•TX messages are not sent on the CAN_PHY_TX bus signal. The controller receives all the messages that it transmits.
•The controller does not receive any messages transmitted by other CAN nodes.