CAN modules UM0404
426/564 DocID13284 Rev 2
The LEC field holds a code which indicates the type of the last error to occur on the CAN
bus. This field will be cleared to ‘0h’ when a message has been transferred (reception or
transmission) without error. The unused code ‘7h’ may be written by the CPU to check for
updates.
Bit Function
LEC
Last Error Code (Type of the last error to occur on the CAN bus)
’000’: No Error.
’001’: Stuff Error: More than 5 equal bits in a sequence have occurred in a part of a
received message where this is not allowed.
’010’: Form Error: A fixed format part of a received frame has the wrong format.
’011’: AckError: The message this CAN Core transmitted was not acknowledged by
another node.
’100’: Bit1Error: During the transmission of a message (with the exception of the
arbitration field), the device wanted to send a recessive level (bit of logical value ‘1’),
but the monitored bus value was dominant.
’101’: Bit0Error: During the transmission of a message (or acknowledge bit, or
active error flag, or overload flag), the device wanted to send a dominant level (data
or identifier bit logical value ‘0’), but the monitored Bus value was recessive. During
busoff recovery this status is set each time a sequence of 11 recessive bits has been
monitored. This enables the CPU to monitor the proceeding of the busoff recovery
sequence (indicating the bus is not stuck at dominant or continuously disturbed).
’110’: CRCError: The CRC check sum was incorrect in the message received, the
CRC received for an incoming message does not match with the calculated CRC for
the received data.
’111’: unused: When the LEC shows the value ‘7’, no CAN bus event was detected
since the CPU wrote this value to the LEC.
TxOk
Transmitted a Message Successfully
’0’: Since this bit was reset by the CPU, no message has been successfully
transmitted. This bit is never reset by the CAN Core.
’1’: Since this bit was last reset by the CPU, a message has been successfully (error
free and acknowledged by at least one other node) transmitted.
RxOk
Received a Message Successfully
’0’: Since this bit was last reset by the CPU, no message has been successfully
received. This bit is never reset by the CAN Core.
’1’: Since this bit was last reset (to zero) by the CPU, a message has been
successfully received (independent of the result of acceptance filtering).
EPass
Error Passive
‘0’: The CAN Core is error active.
‘1’: The CAN Core is in the error passive state as defined in the CAN Specification.
EWarn
Warning Status
‘0’: Both error counters are below the error warning limit of 96.
‘1’: At least one of the error counters in the Error Management Logic has reached
the error warning limit of 96.
BOff
Busoff Status
‘0’: The CAN module is not busoff.
‘1’: The CAN module is in busoff state.
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