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L9669

1.3 Error Management

Ten different errors on the physical buslines can be distinguished:

Not all of these errors leads to a breakdown of the whole communication. So the errors can be categorized into

“negligible” (severity 0), “problematic” (severity 1) and “severe” (severity 2).

Negligible Errors

Transmitter

Error 1, 2, 4 or 8:

In all cases data still can be transmitted in differential mode.

Receiver

Error 1, 2, 5 or 9:

In all cases data still can be received in differential mode.

Problematic Errors

Transmitter

Error 3 or 6:

Data are transmitted using the remaining dataline (single wire).

Receiver

Error 3 or 6:

Data are received using the remaining dataline (single wire).

Severe Errors

Transmitter

Error 5 or 9:

Data are transmitted using the remaining dataline after short circuit detection.

Error 7:

Data are transmitted on CANH or CANL after overcurrent was detected.

Error 10:

Transmission is terminated (fail safe).

Receiver

Error 7:

Data are received on CANH or CANL after detection of permanent dominant state.

Error 4 or 8:

Data are received on CANH or CANL after short circuit was detected.

Error 10:

Data are received normally, error is detected by protocol unit.

Upon any error in normal or RXonly mode the NERR output will be forced LOW and released after error recovery.

N

Type of Errors

Severity

RX

TX

Errors caused by damage of the datalines or isolation

1

CANH wire interrupted (floating or tied to termination)

0

0

2

CANL wire interrupted (floating or tied to termination)

0

0

3

CANH short circuit to VS (overvoltage condition)

1

1

4

CANL short circuit to GND (permanently dominant)

2

0

5

CANH short circuit to GND (permanently recessive)

0

2

6

CANL short circuit to VS (overvoltage condition)

1

1

7

CANL shorted to CANH

2

2

Errors caused by misbehaviour of transceiver stage

8

CANH short circuit to VCC (permanently dominant)

2

0

9

CANL short circuit to VCC (permanently recessive)

0

2

Errors caused by defective protocol unit

10

CANH, CANL driven dominant for more than 1.3 ms

2

2