ST STM32F40 Series Reference Manual page 693

Controller area network (bxCAN)
Bits 6:4 LEC[2:0]
Bit 3 Reserved, must be kept at reset value.
Bit 2 BOFF
Bit 1 EPVF: Error passive flag
Bit 0 EWGF
CAN bit timing register (CAN_BTR)
Address offset: 0x1C
Reset value: 0x0123 0000
This register can only be accessed by the software when the CAN hardware is in
initialization mode.
31 30 29
SILM LBKM
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15 14 13
Reserved
Bit 31 SILM
0: Normal operation
1: Silent Mode
Bit 30 LBKM
0: Loop Back Mode disabled
1: Loop Back Mode enabled
Bits 29:26 Reserved, must be kept at reset value.
693/1422
:
Last error code
This field is set by hardware and holds a code which indicates the error condition of the last
error detected on the CAN bus. If a message has been transferred (reception or
transmission) without error, this field will be cleared to '0'.
The LEC[2:0] bits can be set to value 0b111 by software. They are updated by hardware to
indicate the current communication status.
000: No Error
001: Stuff Error
010: Form Error
011: Acknowledgment Error
100: Bit recessive Error
101: Bit dominant Error
110: CRC Error
111: Set by software
:
Bus-off flag
This bit is set by hardware when it enters the bus-off state. The bus-off state is entered on
TEC overflow, greater than 255, refer to
This bit is set by hardware when the Error Passive limit has been reached (Receive Error
Counter or Transmit Error Counter>127).
:
Error warning flag
This bit is set by hardware when the warning limit has been reached
(Receive Error Counter or Transmit Error Counter≥96).
28 27 26 25
Reserved
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12 11 10 9
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:
Silent mode (debug)
:
Loop back mode (debug)
Doc ID 018909 Rev 4
Section 24.7.6 on page
24 23 22
SJW[1:0] Res.
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8 7 6
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680.
21 20 19
TS2[2:0]
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5 4 3
BRP[9:0]
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RM0090
18 17 16
TS1[3:0]
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2 1 0
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