PIC18F258 Datasheet, PDF (229/384 Pages) Microchip Technology – High Performance, 28/40-Pin Enhanced FLASH Microcontrollers with CAN

PIC18FXX8
FIGURE 19-5:
MESSAGE RECEPTION FLOW CHART
Start
No
Detect
Start of
Message?
Yes
Begin Loading Message into
Message Assembly Buffer (MAB)
Generate
Error
Frame
Valid
No
Message
Received?
Yes
Yesf,omr _{ReeXtBsOcriteriaIdeMnteifisesramgeeets}
Yes, meets criteria
for RXB1
a Filter Criteria?
No
The RXFUL bit determines if the
receive register is empty and able
to accept a new message.
Go to Start
The RXB0DBEN bit determines if
RXB0 can rollover into RXB1 if it is
full.
Is
No
RXFUL = 0?
Is
Yes
RX0DBEN = 1?
Yes
Move Message into RXB0
No
Generate Overrun Error:
Set RXB0OVFL
Generate Overrun Error: ^No
Set RXB1OVFL
Is
RXFUL = 0?
Set RXRDY = 1
Set FILHIT <0>
according to which Filter
Criteria was met
Is
No
ERRIE = 1?
Yes
Go to Start
Yes
Move Message into RXB1
Set RXRDY = 1
Set FILHIT <2:0>
according to which Filter
Criteria was met
Is
Yes
RXIE = 1?
No
Generate
Interrupt
Set CANSTAT <3:0> according
to which Receive Buffer the
Message was loaded into
Yes
Is
RXIE = 1?
No
 2002 Microchip Technology Inc.
Preliminary
DS41159B-page 227