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Figure 13-35: CAN 1 to 3 Definition Registers (C1DEF to C3DEF) (2/3)
Read (2/2)
Bit Position
Bit Name
5
SSHT
4
PBB
3
BERR
2
VALID
1
WAKE
0
OVR
432
Chapter 13 FCAN Interface Function
Defines the single-shot mode for a CAN module.
0: Normal operating mode
1: Single-shot mode
Remarks:
1. In single shot mode the CAN module tries to transmit a message only
once, and the TRQ flag of the corresponding message is cleared
regardless whether the transmission was successful (no error
occurred), or not.
2. In case of an error frame caused during a transmission in single-shot
mode, the CAN module does not launch a re-transmission. However,
error management according to the CAN Protocol is executed (i.e.
generation of error interrupt, incrementing of error counters).
3. The CPU can switch between the normal operating mode and the sin-
gle-shot mode while the CAN module is active without causing any
error on the CAN bus.
Caution:
According to the CAN protocol upon a loss of arbitration a transmit-
ter attempts to re-transmit the message, though loss of arbitration is
not defined as an error.
When single shot mode is set (SSHT = 1), a loss of arbitration is sig-
naled by setting the BERR flag (1). Since the BERR flag signals a
bus error in normal operation, the user must check it in conjunction
with the values of the error counter, in order to judge whether it was
caused by an error or a loss of arbitration.
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.
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 arbi-
tration.
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.
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.
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
CAN baud rate.
Preliminary User's Manual U14913EE1V0UM00
Function
selection is too slow for the selected
MEM
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