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Chapter 14
FCAN Interface Function
Preliminary User’s Manual U15839EE1V0UM00
Figure 14-35:
CAN 1 to 4 Definition Registers (C1DEF to C4DEF) (3/4)
Read (2/2)
Bit Position
Bit Name
Function
4
PBB
Defines the priority by message buffer numbers.
0: Transmission priority is given by message identifier.
1: Transmission priority is given by the number of the message buffer.
Remark:
Normally the message identifier defines the transmission priority. If the
PBB flag is set, the location of a message defines the priority – the lower
the message buffer number the higher the transmission priority.
3
BERR
Indicates a CAN bus error.
0: No CAN bus error occurred since the bit was cleared last.
1: At least one CAN bus error occurred since the flag has been cleared last.
Remark:
For single shot mode (SSHT bit = 1) this flag indicates a loss of the arbitra-
tion.
2
VALID
Indicates valid protocol activity.
0: No valid message was detected by the CAN protocol layer.
1: At least one valid message was received on the CAN bus since the flag has
been cleared last.
1
WAKE
Indicates the wake-up condition from CAN sleep mode.
0: No wake-up, or sleep mode has been terminated by CPU (normal operation).
1: CAN sleep mode has been terminated by detection of CAN bus activity.
0
OVR
Indicates an overrun error.
0: No overrun (normal operation)
1: An overrun occurred during access to the CAN memory.
Remark:
The OVR flag is set, if the CAN message handler is not able to scan all the
message areas defined for the CAN module due to timing problems. The
error interrupt CxINT6 is generated at the same time.
Possible cause for an overrun situation:
The CAN memory access clock f
MEM
selection is too slow for the selected
CAN baud rate.
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