AT32F425
Series Reference Manual
2022.03.30
Page 339
Ver 2.01
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).
19.7.2 CAN mailbox registers
This section describes the registers of the transmit and receive mailboxes. Refer to
section 19.6.5
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. TM2S=1 in the CAN_TSTS register indicates
that the mailbox is empty.
There are three transmit mailboxes and two receive mailboxes. Each receive mailbox has 3-level depth
of FIFO, and can only access to the first received message in the FIFO.
Each mailbox contains four registers.
Figure 19-14
Transmit and receive mailboxes
CAN_RFI0
CAN_RDT0
CAN_RDL0
CAN_RDH0
CAN_RFI0
CAN_RDT0
CAN_RDL0
CAN_RDH0
CAN_RFI0
FIFO0
CAN_RFC0
CAN_RFDTL0
CAN_RFDTH0
CAN_RFI0
CAN_RDT0
CAN_RDL0
CAN_RDH0
CAN_RFI0
CAN_RDT0
CAN_RDL0
CAN_RDH0
CAN_RFI1
FIFO1
CAN_RFC1
CAN_RFDTL1
CAN_RFDTH1
CAN_TMI0
CAN_TMC0
CAN_TMDTL0
CAN_TMDTH0
CAN_TMI1
CAN_TMC1
CAN_TMDTL1
CAN_TMDTH1
CAN_TMI2
CAN_TMC2
CAN_TMDTL2
CAN_TMDTH2
Transmit mailboxes
19.7.2.1 Transmit mailbox identifier register ( CAN_TMIx) (x=0..2)
Note: 1. This register is write protected when its mailboxes are pending for transmission.
2.This register implements the Transmit Request control (bit 0)
— reset value 0.
Bit
Register
Reset value
Type
Description
Bit 31: 21 TMSID/ TMEID
0xXXX
rw
Transmit mailbox standard identifier or extended identifier
high bytes
Note: This field defines the 11-bit high bytes of the
standard identifier or extended identifier.
Bit 20: 3
TMEID
0xXXXXX
rw
Transmit mailbox extended identifier
Note: This field defines the 18-bit low bytes of the extended
identifier.
Bit 2
TMIDSEL
0xX
rw
Transmit mailbox identifier type select
0: Standard identifier
1: Extended identifier
Bit 1
TMFRSEL
0xX
rw
Transmit mailbox frame type select
0: Data frame
1: Remote frame
Bit 0
TMSR
0x0
rw
Transmit mailbox send request
0: No effect
1: Transmit request
Note: This bit is cleared by hardware when the
transmission has been completed (The mailbox becomes
empty)