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M16C/5L Group, M16C/56 Group
23.1.25.3 Listen-Only Mode
The ISO 11898-1 recommends an optional bus monitoring mode. In listen-only mode, the CAN node is
able to receive valid data frames and valid remote frames. It sends only recessive bits on the CAN bus
and the protocol controller is not required to send the ACK bit, overload flag, or active error flag.
Listen-only mode can be used for baud rate detection.
Do not request transmission from any mailboxes in this mode.
Figure 23.31 shows the connection when listen-only mode is selected.
Figure 23.31 Connection when Listen-Only Mode is Selected
23.1.25.4 Self-Test Mode 0 (External Loop Back)
Self-test mode 0 is provided for CAN transceiver tests.
In this mode, the protocol controller treats its own transmitted messages as messages received via the
CAN transceiver and stores them into the receive mailbox. To be independent from external stimulation,
the protocol controller generates the ACK bit.
Connect the CTX0/CRX0 pins to the transceiver.
Figure 23.32 shows the connection when self-test mode 0 is selected.
Figure 23.32 Connection when Self-Test Mode 0 is Selected
R01UH0127EJ0110 Rev.1.10
Sep 01, 2011
CTX0
CRX0
Recessive level
CTX0
CRX0
internal
internal
CAN transceiver
CTX0
CRX0
ACK
CTX0
CRX0
internal
internal
23. CAN Module
Page 596 of 803
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