Microchip Technology dsPIC33 series User Manual

dsPIC33/PIC24 Family Reference Manual
DS70005340A-page 82  2018 Microchip Technology Inc.
Figure 8-1: Message Filtering Flow
8.2.1 FILTERING STANDARD OR EXTENDED FRAMES
Figure 8-2 illustrates the flow of matching a single filter object to the received message in the
RXMAB.
The filter object can be configured to accept either standard, extended or both frames. If MIDE
is clear, both standard and extended frames will be accepted.
If the filter should only accept standard frames, then MIDE must be set and EXIDE must be
cleared. If the filter should only accept extended frames, then both MIDE and EXIDE must be set.
8.2.2 MASK BITS
The mask object is used to ignore selected bits of the received identifier. The masked bits (mask
bits with a value of ‘0’) of the RXMAB will not be compared with the bits in the filter object. For
example, to receive all messages with Identifiers 0, 1, 2 and 3, it is required to mask the lower
two bits of the identifier by clearing the corresponding bits of the mask object.
Match Filter Object 0
Match Filter Object 1
No
FIFO Not Full?
Index = F0BP
Yes and Not RTR
No
Accept Message:
Receive Rest of Message
Store in FIFO [Index]
Yes
FIFO Not Full?
Index = F1BP
Yes and Not RTR
No
Yes
Match Filter Object 31
FIFO Not Full?
Index = F31BP
Yes and Not RTR
No
Yes
No
Discard Message
Done
No
Yes and RTR
FIFO Not Empty and
TXEN = 1 and RTREN = 1?
Index = F0BP
No
Set TXREQ[Index]
Yes
Yes and RTR
FIFO Not Empty and
TXEN = 1 and RTREN = 1?
Index = F1BP
Yes and RTR
FIFO Not Empty and
TXEN = 1 and RTREN = 1?
Index = F31BP
No
No
Yes
Yes
Arbitration Done and
Required Data Bytes Received
Match Filter Object 2-30
Do the Same

Microchip Technology dsPIC33 series Specifications

General

Brand	Microchip Technology
Model	dsPIC33 series
Category	Motherboard
Language	English