ST ST10F276E - Message Handler Registers

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UM0404 CAN modules
21.8.4 Message handler registers
All Message Handler registers are read-only. Their contents (TxRqst, NewDat, IntPnd, and
MsgVal bits of each Message Object and the Interrupt Identifier) is status information
provided by the Message Handler FSM.
Interrupt register
CAN1IR (EF08h) XBUS Reset Value: 0000h
CAN2IR (EE08h) XBUS Reset Value: 0000h
TxRqst
Transmit Request
’0’: This Message Object is not waiting for transmission.
’1’: The transmission of this Message Object is requested and is not yet done.
DLC(3:0)
Data Length Code
’0000’: Data Frame has 0 data byte.
’0001’: Data Frame has 1 data byte.
’1000’: Data Frame has 8 data bytes.
’1001’: Data Frame has 8 data bytes.
’1111’: Data Frame has 8 data bytes.
Note: The Data Length Code of a Message Object must be defined the same as in
all the corresponding objects with the same identifier at other nodes. When the
Message Handler stores a data frame, it will write the DLC to the value given by the
received message.
Data 0
Data 1
Data 2
Data 3
Data 4
Data 5
Data 6
Data 7
1st data byte of a CAN Data Frame
2nd data byte of a CAN Data Frame
3rd data byte of a CAN Data Frame
4th data byte of a CAN Data Frame
5th data byte of a CAN Data Frame
6th data byte of a CAN Data Frame
7th data byte of a CAN Data Frame
8th data byte of a CAN Data Frame
Note: Byte Data 0 is the first data byte shifted into the shift register of the CAN Core
during a reception, byte Data 7 is the last. When the Message Handler stores a Data
Frame, it will write all the eight data bytes into a Message Object. If the Data Length
Code is less than 8, the remaining bytes of the Message Object will be overwritten
by non specified values.
Bit Function
1514131211109876543210
IntId(15:0)
R