ST STM32F101 Series Reference Manual page 306

Controller area network (bxCAN)
Rx FIFO mailbox identifier register (CAN_RIxR) (x=0..1)
Address offsets: 0x1B0, 0x1C0
Reset value: 0xXX where X is undefined
Note: All RX registers are write protected.
31 30 29
r r r
15 14 13
r r r
Bits 31:21 STID[10:0]: Standard Identifier
The standard part of the identifier.
Bits 20:3 EXID[17:0]: Extended Identifier
The extended part of the identifier.
Bit 2 IDE: Extended Identifier
This bit defines the identifier type of message in the mailbox.
0: Standard identifier.
1: Extended identifier.
Bit 1 RTR: Remote Transmission Request
0: Data frame
1: Remote frame
Bit 0 Reserved
306/501
28 27 26 25
STID[10:0]
r r r r
12 11 10 9
EXID[12:0]
r r r r
24 23 22 21
r r r r
8 7 6 5
r r r r
20 19 18 17
EXID[17:13]
r r r r
4 3 2 1
IDE RTR
r r r r
RM0008
16
r
0
Res.