ST STM32F101 Series Reference Manual page 308

Controller area network (bxCAN)
Bits 15:8 DATA1[7:0]: Data Byte 1
Data byte 1 of the message.
Bits 7:0 DATA0[7:0]: Data Byte 0
Data byte 0 of the message.
A message can contain from 0 to 8 data bytes and starts with byte 0.
Receive FIFO mailbox data high register (CAN_RDHxR) (x=0..1)
Address offsets: 0x1BC, 0x1CC
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 31:24 DATA7[7:0]: Data Byte 7
Data byte 3 of the message.
Bits 23:16 DATA6[7:0]: Data Byte 6
Data byte 2 of the message.
Bits 15:8 DATA5[7:0]: Data Byte 5
Data byte 1 of the message.
Bits 7:0 DATA4[7:0]: Data Byte 4
Data byte 0 of the message.
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28 27 26 25
DATA7[7:0]
r r r r
12 11 10 9
DATA5[7:0]
r r r r
24 23 22 21
r r r r
8 7 6 5
r r r r
20 19 18 17
DATA6[7:0]
r r r r
4 3 2 1
DATA4[7:0]
r r r r
RM0008
16
r
0
r