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CP3BT26

19.10.15 CAN Error Counter Register (CANEC)

The CANEC register reports the values of the CAN Receive

Error Counter and the CAN Transmit Error Counter.

REC The CAN Receive Error Counter field reports

the value of the receive error counter.

TEC The CAN Transmit Error Counter field reports

the value of the transmit error counter.

19.10.16 CAN Error Diagnostic Register (CEDIAG)

The CEDIAG register reports information about the last de-

tected error. The CAN module identifies the field within the

CAN frame format in which the error occurred, and it identi-

fies the bit number of the erroneous bit within the frame

field. The CPU bus master has read-only access to this reg-

ister, and all bits are cleared on reset.

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

Tab l e 63.

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-

ue equal to the respective frame field length

minus one at the beginning of each field and

is decremented with each CAN bit. Figure 63

shows an example on how the EBID is calcu-

lated.

Figure 63. 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.

TXE 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.

STUFF 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.

0 – No bit stuffing error.

1 – The bit stuffing rule was violated at the

time the error occurred.

CRC The CRC Error bit indicates whether the CRC

is invalid. This bit should only be checked if

the EFID field shows the code of the ACK

field.

0 – No CRC error occurred.

1 – CRC error occurred.

MON The Monitor bit shows the bus value on the

CANRX pin as sampled by the CAN module at

the time of the error.

15 8 7 0

REC TEC

15 14 13 12 11 10 9 4 3 0

Res. DRIVE MON CRC STUFF TXE EBID EFID

Table 63 Error Field Identifier

EFID3:0 Field

0000 ERROR

0001 ERROR DEL

0010 ERROR ECHO

0011 BUS IDLE

0100 ACK

0101 EOF

0110 INTERMISSION

0111 SUSPEND

TRANSMISSION

1000 SOF

1001 ARBITRATION

1010 IDE

1011 EXTENDED

ARBITRATION

1100 R1/R0

1101 DLC

1110 DATA

1111 CRC

Table 63 Error Field Identifier

EFID3:0 Field

Data Field

Incorrect

Bit

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DS047