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CONTROLLER AREA NETWORK (bxCAN)

CONTROLLER AREA NETWORK (Cont’d)

CAN ERROR STATUS REGISTER (CESR)

Read / Write

Reset Value: 0000 0000 (00h)

Bit 7 = Reserved. Forced to 0 by hardware.

Bit 6:4 = LEC[2:0] Last Error Code

- Read/Set/Clear

This field holds a code which indicates the type of

the last error detected on the CAN bus. If a mes-

sage has been transferred (reception or transmis-

sion) without error, this field will be cleared to ‘0’.

The code 7 is unused and may be written by the

CPU to check for update

Table 63. LEC Error Types

Bit 3 = Reserved. Forced to 0 by hardware.

Bit 2 = BOFF Bus-Off Flag

- Read

This bit is set by hardware when it enters the bus-

off state. The bus-off state is entered on TECR

overrun, TEC greater than 255, refer to Section

10.10.5.6 on page 338.

Bit 1 = EPVF Error Passive Flag

- Read

This bit is set by hardware when the Error Passive

limit has been reached (Receive Error Counter or

Transmit Error Counter greater than 127).

Bit 1 = EWGF Error Warning Flag

- Read

This bit is set by hardware when the warning limit

has been reached. Receive Error Counter or

Transmit Error Counter greater than 96.

CAN ERROR INTERRUPT ENABLE REGISTER

(CEIER)

All bits of this register are set and clear by soft-

ware.

Read/Write

Reset Value: 0000 0000 (00h)

Bit 7 = ERRIE Error Interrupt Enable

0: No interrupt will be generated when an error

condition is pending in the CESR.

1: An interrupt will be generated when an error

condition is pending in the CESR.

Bit 6:5 = Reserved. Forced to 0 by hardware.

Bit 4 = LECIE Last Error Code Interrupt Enable

0: ERRI bit will not be set when the error code in

LEC[2:0] is set by hardware on error detection.

1: ERRI bit will be set when the error code in

LEC[2:0] is set by hardware on error detection.

Bit 3 = Reserved. Forced to 0 by hardware.

Bit 2 = BOFIE Bus-Off Interrupt Enable

0: ERRI bit will not be set when BOFF is set.

1: ERRI bit will be set when BOFF is set.

Bit 1 = EPVIE Error Passive Interrupt Enable

0: ERRI bit will not be set when EPVF is set.

1: ERRI bit will be set when EPVF is set.

Bit 0 = EWGIE Error Warning Interrupt Enable

0: ERRI bit will not be set when EWGF is set.

1: ERRI bit will be set when EWGF is set.

Note: refer to Standard Interrupts Section.

LEC2

LEC1

LEC0

BOFF

EPVF EWGF

Code

Error Type

0No Error

Stuff Error

2Form Error

Acknowledgment Error

Bit recessive Error

Bit dominant Error

CRC Error

Set by software

ERRIE

LECIE

BOFIE EPVIE EWGIE

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