Fujitsu FR81S User Manual
CHAPTER 41: CAN
5. Operation
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER
: CAN
FUJITSU SEMICONDUCTOR CONFIDENTIAL
64
5.2.1. Message Transmission
Message transmission is shown.
If there is no data transfer between the message interface register and message RAM, the MsgVal bit of the
CAN message valid register (MSGVAL) and the TxRqst bit of the CAN transmission request register
(TREQR) will be evaluated. Of all message objects with pending transmission request, a valid message
object having the highest priority will be transferred to the transmission shift register. The NewDat bit of
the message object will be cleared to "0" at this time.
The TxRqst bit will be reset to "0" if there is no new data in the message object (NewDat=0) when the
transmission has ended successfully. If the TxIE is set to "1", the IntPnd bit will be set to "1" after the
transmission has ended successfully. If the CAN controller has lost the arbitration on the CAN bus or an
error has occurred during the transfer, message will be retransmitted immediately when the CAN bus
becomes idle.
MB91520 Series
MN705-00010-1v0-E
1757