Microchip Technology dsPIC30F - Page 639

© 2004 Microchip Technology Inc. DS70070B-page 23-41
Section 23. CAN
CAN Module
23
Figure 23-9: Receive Flowchart
START
Detect
Start of
Message
?
Valid
Message
Received
?
Generate
Error
Message
Identifier meets
a filter criteria
?
Is
RXFUL = 0
?
Go to Start
Move message into RXB0
Set RXFUL = 1
Set FILHIT<2:0>
Is
RXFUL = 0
?
Move message into RXB1
Set RXFUL = 1
Yes, meets criteria
for RXB0
Yes, meets criteria
for RXB1
No
Generate
Interrupt
Yes
Yes
No
No
Yes
Yes
No
No
Yes
Yes
Frame
The RXFUL bit determines if the
receive register is empty and
able to accept a new message.
No
Yes
No
Generate Overrun Error:
Begin Loading Message into
Message Assembly Buffer (MAB)
was met
Is
RXnIE = 1
?
Does
RXnIE = 1
?
Is
DBEN = 1
?
The DBEN bit determines if
RXB0 can roll over into
RXB1 if it is full.
Set RX0OVR
Generate Overrun Error:
Set RX1OVR
Does
ERRIE=1
?
No
Go to Start
Yes
No
Set FILHIT<0>
according to which filter criteria
was met
Set ICODE<3:0> according
to which receive buffer the
message was loaded into
according to which filter criteria