Message Object In The Message Memory - Fujitsu MB96300 series Hardware Manual

MB96300 Super Series Hardware Manual
22.7

Message Object in the Message Memory

There are 32 Message Objects (up to 128 depending on the implementation) in the
Message RAM. To avoid conflicts between CPU access to the Message RAM and CAN
message reception and transmission, the CPU cannot directly access the Message
Objects, these accesses are handled via the IFx Interface Registers.
■ Structure of a Message Object in the Message Memory
Figure 22.7-1 "Structure of a Message Object in the Message Memory" gives an overview of the two
structure of a Message Object.
Figure 22.7-1 Structure of a Message Object in the Message Memory
UMASK MSK28-0 MXTD
MSGVAL ID28-0 XTD
MSGVAL Message Valid
0 The Message Object is ignored by the Message Handler.
1 The Message Object is configured and should be considered by the Message Handler.
Note:
The CPU must reset the MSGVAL bit of all unused Messages Objects during the initialization before it
resets bit INIT in the CAN Control Register. This bit must also be reset before the identifier ID28-0, the
control bits XTD, DIR, or the Data Length Code DLC3-0 are modified, or if the Message Object is no
longer required.
UMASK Use Acceptance Mask
0 Mask ignored.
1 Use Mask (MSK28-0, MXTD, and MDIR) for acceptance filtering.
Note:
If the UMASK bit is set to one, the Message Object's mask bits have to be programmed during
initialization of the Message Object before MSGVAL is set to "1".
ID28-0 Message Identifier
ID28 - ID0 29-bit Identifier ("Extended Frame").
ID28 - ID18 11-bit Identifier ("Standard Frame").
Message Object
MDIR EOB NEWDAT
DIR DLC3-0 Data0
CHAPTER 22 CAN CONTROLLER
MSGLST RXIE
Data1 Data2 Data3
TXIE INTPND RMTEN
Data4 Data5 Data6
TXRQST
Data7
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