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GD32A50x User Manual
631
bus idle condition (the sequence of 11 consecutive recessive bits) is detected. Refer to the
CAN Protocol standard (ISO 11898-1).
The protocol exception detection is controlled by PREEN bit in CAN_CTL2 register.
The edge filtering can be configured by EFDIS bit in CAN_CTL2 register, which is used during
the bus integration state. When the edge filtering is enabled, two consecutive nominal time
quanta with dominant bus state are required to detect an edge that causes synchronization.
When synchronization occurs, the counting for
bus idle condition (the sequence of 11
consecutive recessive bits
) is restarted. When edge filtering is performed, dominant bus-
states shorter than a nominal bit time (the bits in data phase of a FD frame) will be ignored,
stopped from being mistaken for an idle condition.
Refer to the CAN Protocol standard (ISO
11898-1).
Errors
If at least one of the error flags (ACKERR, BRERR, BDERR, CRCERR, FMERR, and
STFERR bit in CAN_ERR1 register
) is set, ERRSF bit in CAN_ERR1 register will be set. If
ERRSIE bit in CAN_CTL1 register is set, an error interrupt will be generated.
If at least one of the error flags (BRFERR, BDFERR, CRCFERR, FMFERR, and STFFERR
bit in CAN_ERR1 register
) is set, ERRFSF bit in CAN_ERR1 register will be set. If ERRFSIE
bit in CAN_CTL2 register is set, an error interrupt will be generated for errors detected in CAN
FD frame data phase with BRS bit set.
Acknowledge error
If there is only one node operating, then it will lead to TECNT[7:0] in CAN_ERR0 register
incrementing (to 128 at most by acknowledge error) in each message transmission, and an
acknowledge error will occur, which is indicated by ACKERR bit in the CAN_ERR1 register.
Bit recessive error
When at least one bit sent as recessive ‘1’ is received as dominant ‘0’, a bit recessive error
occurs. Refers to BRFERR and BRERR bit in CAN_ERR1 register.
Bit dominant error
When at least one bit sent as dominant ‘0’ is received as recessive ‘1’, a bit dominant error
occurs. Refers to BDFERR and BDERR bit in CAN_ERR1 register.
CRC error
When the calculated CRC is different from the received CRC field of the frame, a CRC error
occurs. Refers to CRCFERR and CRCERR bit in CAN_ERR1 register.
Form error
When a fixed-form bit field contains at least one illegal bit, a form error occurs. Refers to
FMFERR and FMERR bit in CAN_ERR1 register.