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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 337
.
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.
7
0
0
LEC2
LEC1
LEC0
0
BOFF
EPVF EWGF
Code
0
1
2
3
4
5
6
7
Error Type
No Error
Stuff Error
Form Error
Acknowledgment Error
Bit recessive Error
Bit dominant Error
CRC Error
Set by software
7
0
ERRIE
0
0
LECIE
0
BOFIE EPVIE EWGIE
9