Fujitsu FR81S User Manual
CHAPTER 41: CAN
5. Operation
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER
: CAN
FUJITSU SEMICONDUCTOR CONFIDENTIAL
78
5.4.3. Reading from FIFO Buffer
Reading from FIFO buffer is shown.
CPU can read the content of the received message object by writing the reception message number to the
IFx command request register (IFxCREQ) that will cause the message object to be transferred to the
message interface register. Set the WR/RD to "0" (read), set the TxRqst/NewDat and the IntPnd to "1" and
reset NewDat and IntPnd bits to "0" in the IFx command mask register (IFxCMSK) at this time.
In order to guarantee the function of the FIFO buffer, always read the reception message objects in the FIFO
buffer starting from the one having the smallest message number.
The figure below shows the CPU processing method for the message objects that are linked in the FIFO
buffer.
MB91520 Series
MN705-00010-1v0-E
1771