17 can message data low register – Rainbow Electronics AT91CAP9S250A User Manual
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6264A–CAP–21-May-07
AT91CAP9S500A/AT91CAP9S250A
39.8.17
CAN Message Data Low Register
Name:
CAN_MDLx
Access Type:
Read/Write
• MDL: Message Data Low Value
When MRDY field is set in the CAN_MSRx register, the lower 32 bits of a received message can be read or written by the
software application. Otherwise, the MDL value is locked by the CAN controller to send/receive a new message.
In Receive with overwrite, the CAN controller may modify MDL value while the software application reads MDH and MDL
registers. To check that MDH and MDL do not belong to different messages, the application has to check the MMI field in
the CAN_MSRx register. In this mode, the software application must re-read CAN_MDH and CAN_MDL, while the MMI bit
in the CAN_MSRx register is set.
Bytes are received/sent on the bus in the following order:
1.
CAN_MDL[7:0]
2.
CAN_MDL[15:8]
3.
CAN_MDL[23:16]
4.
CAN_MDL[31:24]
5.
CAN_MDH[7:0]
6.
CAN_MDH[15:8]
7.
CAN_MDH[23:16]
8.
CAN_MDH[31:24]
31
30
29
28
27
26
25
24
MDL
23
22
21
20
19
18
17
16
MDL
15
14
13
12
11
10
9
8
MDL
7
6
5
4
3
2
1
0
MDL