70353C Datasheet, PDF (29/76 Pages) Microchip Technology – Section 21. Enhanced Controller Area Network

Section 21. Enhanced Controller Area Network (ECAN™)
21.4 ECAN MESSAGE BUFFERS
ECAN message buffers are located in device RAM. They are not ECAN SFRs. The user
application must directly write into the device RAM area that is configured for ECAN message
buffers. The location and size of the buffer area is defined by the user application.
This section provides information on how the message buffer words are organized for
transmission and reception. (See also 21.2 “CAN Message Formats” for message buffer layout
details and 21.8 “DMA Controller Configuration” for details on how to configure ECAN
message buffers in device RAM).
Buffer 21-1:
U-x
—
bit 15
ECAN Message Buffer Word 0
U-x
U-x
R/W-x
—
—
R/W-x
R/W-x
SID<10:6>
R/W-x
R/W-x
bit 8
R/W-x
bit 7
R/W-x
R/W-x
R/W-x
SID<5:0>
R/W-x
R/W-x
R/W-x
SRR
R/W-x
IDE
bit 0
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
x = Bit is unknown
bit 15-13
bit 12-2
bit 1
bit 0
Buffer 21-2:
U-x
—
bit 15
Unimplemented: Read as ‘0’
SID<10:0>: Standard Identifier bits
SRR: Substitute Remote Request bit
When IDE = 0:
1 = In case of Transmission, this will cause a Remote Frame to be transmitted. In case of Received
message, indicates a remote frame was received.
0 = Normal message
When IDE = 1:
The SRR bit must be set to ‘1’
IDE: Extended Identifier bit
1 = Message will transmit extended identifier or received message has an extended identifier
0 = Message will transmit standard identifier or received message has a standard identifier
ECAN Message Buffer Word 1
U-x
U-x
U-x
—
—
—
R/W-x
R/W-x
R/W-x
EID<17:14>
R/W-x
bit 8
R/W-x
bit 7
R/W-x
R/W-x
R/W-x
R/W-x
EID<13:6>
R/W-x
R/W-x
R/W-x
bit 0
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
x = Bit is unknown
bit 15-12
bit 11-0
Unimplemented: Read as ‘0’
EID<17:6>: Extended Identifier bits
21
© 2008-2011 Microchip Technology Inc.
DS70353C-page 21-29