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AT32F435/437
Series Reference Manual
2022.11.11
Page 415
Rev 2.03
Note:
This field is used to indicate the current error type. It is set
by hardware according to the error condition detected on
the CAN bus. It is cleared by hardware when a message
has been transmitted or received successfully.
If the error code 7 is not used by hardware, this field can
be set by software to monitor the code update.
Bit 3
Reserved
0x0
resd
Kept at its default value.
Bit 2
BOF
0x0
ro
Bus-off flag
0: Bus-off state is not entered.
1: Bus-off state is entered.
Note: When the TEC is greater than 255, the bus-off state
is entered, and this bit is set by hardware.
Bit 1
EPF
0x0
ro
Error passive flag
0: Error passive state is not entered
1: Error passive state is entered
Note: This bit is set by hardware when the current error
times has reached the Error passive state limit (Receive
Error Counter or Transmit Error Counter >127)
Bit 0
EAF
0x0
ro
Error active flag
0: Error active state is not entered
1: Error active state is entered
Note: This bit is set by hardware when the current error
times has reached the Error active state limit (Receive
Error Counter or Transmit Error Counter ≥96)
20.7.1.8 CAN bit timing register (CAN_BTMG)
Bit
Register
Reset value
Type
Description
Bit 31
LOEN
0x0
rw
Listen-Only mode
0: Listen-Only mode disabled
1: Listen-Only mode enabled
Bit 30
LBEN
0x0
rw
Loop back mode
0: Loop back mode disabled
1: Loop back mode enabled
Bit 29: 26 Reserved
0x0
resd
Kept at its default value.
Bit 25: 24 RSAW
0x1
rw
Resynchronization width
tRSAW = tCAN x (RSAW[1: 0] + 1)
Note: This field defines the maximum of time unit that the
CAN hardware is allowed to lengthen or shorten in a bit.
Bit 23
Reserved
0x0
resd
Kept at its default value.
Bit 22: 20 BTS2
0x2
rw
Bit time segment 2
tBTS2 = tCAN x (BTS2[2: 0] + 1)
Note: This field defines the number of time unit in Bit time
segment 2.
Bit 19: 16 BTS1
0x3
rw
Bit time segment 1
tBTS1 = tCAN x (BTS1[3: 0] + 1)
Note: This field defines the number of time unit in Bit time
segment 1.
Bit 15: 12 Reserved
0x0
resd
Kept at its default value.
Bit 11: 0
BRDIV
0x000
rw
Baud rate division
tq = (BRDIV[11: 0]+1) x tPCLK
Note: This field defines the length of a time unit (tq).
20.7.2 CAN mailbox registers
This section describes the registers of the transmit and receive mailboxes. Refer to
for more
information on register map.
Transmit and receive mailboxes are the same except:
RFFMN field in the CAN_RFCx register
A receive mailbox is read only
A transmit mailbox can be written only when empty. TMxEF=1 in the CAN_TSTS register
indicates that the mailbox is empty.