CONTROLLER AREA NETWORK (bxCAN)
CONTROLLER AREA NETWORK (Cont’d)
10.10.5.5 Message Storage
Receive Mailbox
The interface between the software and the hard-
ware for the CAN messages is implemented by
means of mailboxes. A mailbox contains all infor-
mation related to a message; identifier, data, con-
trol, status and time stamp information.
When a message has been received, it is available
to the software in the FIFO output mailbox. Once
the software has handled the message (e.g. read
it) the software must release the FIFO output mail-
box by means of the RFOM bit in the CRFR regis-
ter to make the next incoming message available.
The filter match index is stored in the MFMI regis-
ter. The 16-bit time stamp value is stored in the
MTSR[0:1] registers.
Transmit Mailbox
The software sets up the message to be transmit-
ted in an empty transmit mailbox. The status of the
transmission is indicated by hardware in the
MCSR register.
Receive Mailbox Mapping
Offset to Receive
Transmit Mailbox Mapping
Mailbox base ad-
dress (bytes)
Register Name
Offset to Transmit
Mailbox base ad-
dress (bytes)
Register Name
0
1
MFMI
MDLC
0
1
MCSR
2
MIDR0
MIDR1
MIDR2
MIDR3
MDAR0
MDAR1
MDAR2
MDAR3
MDAR4
MDAR5
MDAR6
MDAR7
MTSR0
MTSR1
MDLC
3
2
MIDR0
MIDR1
MIDR2
MIDR3
MDAR0
MDAR1
MDAR2
MDAR3
MDAR4
MDAR5
MDAR6
MDAR7
MTSR0
MTSR1
4
3
5
4
6
5
7
6
8
7
9
8
10
11
12
13
14
15
9
10
11
12
13
14
15
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STMICROELECTRONICS [ ST ]
