CP3BT23 Datasheet, PDF (123/260 Pages) Texas Instruments – CP3BT23 Reprogrammable Connectivity Processor with Bluetooth and Dual CAN Interfaces

18.10.15 CAN Error Counter Register (CANECn)
Table 56 Error Field Identifier
The CANECn register reports the values of the CAN Re-
ceive Error Counter and the CAN Transmit Error Counter.
EFID3:0
1101
Field
DLC
15
8
7
0
1110
DATA
REC
TEC
1111
CRC
0
R
EBID
The Error Bit Identifier field reports the bit po-
sition of the incorrect bit within the erroneous
frame field. The bit number starts with the val-
REC
The CAN Receive Error Counter field reports
ue equal to the respective frame field length
the value of the receive error counter.
minus one at the beginning of each field and
TEC
The CAN Transmit Error Counter field reports
is decremented with each CAN bit. Figure 61
the value of the transmit error counter.
18.10.16 CAN Error Diagnostic Register (CEDIAGn)
The CEDIAGn register reports information about the last
detected error. The CAN module identifies the field within
the CAN frame format in which the error occurred, and it
identifies the bit number of the erroneous bit within the
frame field. The CPU bus master has read-only access to
te this register, and all bits are cleared on reset.
15 14 13 12 11 10 9 4 3 0
Res. DRIVE MON CRC STUFF TXE EBID EFID
0
le ^R
Obso ^EFID
The Error Field Identifier field identifies the
frame field in which the last error occurred.
The encoding of the frame fields is shown in
Table 56.
Table 56 Error Field Identifier
TXE
EFID3:0
Field
0000
0001
0010
0011
0100
0101
ERROR
ERROR DEL
ERROR ECHO
BUS IDLE
ACK
EOF
STUFF
shows an example on how the EBID is calcu-
lated.
rrrrrr
Incorrect
Bit
Data Field
DS047
Figure 61. EBID Example
For example, assume the EFID field shows
1110b and the EBID field shows 111001b.
This means the faulty field was the data field.
To calculate the bit position of the error, the
DLC of the message needs to be known. For
example, for a DLC of 8 data bytes, the bit
counter starts with the value: (8 × 8) - 1 = 63;
so when EBID[5:0] = 111001b = 57, then the
bit number was 63 - 57 = 6.
The Transmit Error bit indicates whether the
CAN module was an active transmitter at the
time the error occurred.
0 – The CAN module was a receiver at the
time the error occurred.
1 – The CAN module was an active transmit-
ter at the time the error occurred.
The Stuff Error bit indicates whether the bit
stuffing rule was violated at the time the error
occurred. Note that certain bit fields do not
use bit stuffing and therefore this bit may be
ignored for those fields.
0110
INTERMISSION
0 – No bit stuffing error.
0111
1000
SUSPEND
TRANSMISSION
SOF
CRC
1 – The bit stuffing rule was violated at the
time the error occurred.
The CRC Error bit indicates whether the CRC
is invalid. This bit should only be checked if
1001
1010
ARBITRATION
IDE
the EFID field shows the code of the ACK
field.
0 – No CRC error occurred.
1011
EXTENDED
ARBITRATION
MON
1 – CRC error occurred.
The Monitor bit shows the bus value on the
1100
R1/R0
CANRX pin as sampled by the CAN module at
the time of the error.
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