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CHAPTER 22 CAN CONTROLLER
Depending on the exact time when TXRQST was set to 0, the message may not be transmitted
immediately after setting TXRQST = "1", but after any of the following events:
1. there is activity ongoing on the CANbus
2. a transmission request is issued on another message object
3. the CANbus is initialized by the INIT bit
In general, there is no need to cancel an ongoing transmission by setting TXRQST = 0. If the content of a
message object needs to be changed while TXRQST = 1, it is sufficient to update the message object via
the CPU interface registers (Identifier, DLC, Data, with TXRQST and NEWDAT, optionally TXIE). The
updated content will be transmitted at the next opportunity.
DLC3-0
Data Length Code
0-8
Data Frame has 0-8 data bytes.
9-15
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.
Data0
Data1
Data2
Data3
Data4
Data5
Data6
Data7
Note:
Byte Data0 is the first data byte shifted into the shift register of the CAN Core during a reception, byte
Data7 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.
610
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
MB96300 Super Series Hardware Manual
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