Fujitsu FR81S User Manual
CHAPTER 41: CAN
5. Operation
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER
: CAN
FUJITSU SEMICONDUCTOR CONFIDENTIAL
67
5.2.4. Update of Transmission Message Object
Update of transmission message object is shown.
CPU can update the data of the transmission message object via the message interface register.
Data of the transmission message object will be written in units of 4 bytes of the corresponding IFx data
register (IFxDTx) (in unit of the IFx data register A (IFxDTAx) or IFx data register B (IFxDTBx)).
Therefore, it is not possible to change only 1 byte of the transmission message object.
0087
H
will be written to the IFx command mask register (IFxCMSK) first when updating 8-byte data. Then,
data of the transmission message object (8-byte data) will be updated and "1" will be written to the TxRqst
bit at the same time when a message number is written to the IFx command request register (IFxCREQ).
If the NewDat bit and TxRqst bit are both "1", the NewDat bit will be reset to "0" when the transmission
starts.
Notes:
⋅
When updating data, perform it in units of 4 bytes of the IFx data register A(IFxDTAx) or IFx data
register B(IFxDTBx).
⋅
When the TxRqst bit is "1", do not change the message objects of ID28 to 0, DLC3 to 0, Xtd, and
Data7 to 0. Otherwise, message objects before and after the change may be transmitted in a mixed way
or message objects after the change may not be transmitted. Change them when the TxRqst bit is "0".
MB91520 Series
MN705-00010-1v0-E
1760