COMMELL MPX-2515 User Manual
Page 21
Commell MPX-2515 User’s Guide Rev 0100
Taiwan Commate Computer Inc.
21
Figure 6 Masks and Filters Apply to CAN Frames
FILHIT BITS
Filter matches on received messages can be determined by the FILHIT bits in the
associated RXBnCTRL register. RXB0CTRL.FILHIT0 for buffer 0 and
RXB1CTR.FILHIT<2:0> for buffer 1.
The three FILHIT<2:0> bits for receive buffer 1 (RXB1) are coded as follows:
•
101 = Acceptance filter 5 (RXF5)
•
100 = Acceptance filter 4 (RXF4)
•
011 = Acceptance filter 3 (RXF3)
•
010 = Acceptance filter 2 (RXF2)
•
001 = Acceptance filter 1 (RXF1)
•
000 = Acceptance filter 0 (RXF0)
Note: 000 and 001 can only occur if the BUKT bit in RXB0CTRL is set, allowing
RXB0 message to roll over into RXB1.
RXB0CTRL contains two copies of the BUKT bit and the FILHIT<0> bit.
The coding of the BUKT bit enables these three bits to be used similarly to the
RXB1CTRL.FILHIT bits and to distinguish a hit on filter RXF0 and RXF1 in either
RXB0 or after a roll over into RXB1.
•
111 = Acceptance Filter 1 (RXB1)
•
110 = Acceptance Filter 0 (RXB1)
•
001 = Acceptance Filter 1 (RXB0)
•
000 = Acceptance Filter 0 (RXB0)