atmega32c1 ATMEL Corporation, atmega32c1 Datasheet - Page 179

• Manufacturer Part Number: atmega32c1
• Description: Atmega32m1 Automotive 8-bit Avr Microcontroller With 32k/64k Bytes In-system Programmable Flash
• Manufacturer: ATMEL Corporation

16.5.3
16.5.4
16.5.5
7647A–AVR–02/08
Acceptance Filter
MOb Page
CAN Data Buffers
Upon a reception hit (i.e., a good comparison between the ID + RTR + RBn + IDE received and an
IDT+ RTRTAG + RBnTAG + IDE specified while taking the comparison mask into account) the IDT
+ RTRTAG + RBnTAG + IDE received are updated in the MOb (written over the registers).
Figure 16-10. Acceptance Filter Block Diagram
Note:
Every MOb is mapped into a page to save place. The page number is the MOb number. This
page number is set in CANPAGE register. The other numbers are reserved for factory tests.
CANHPMOB register gives the MOb having the highest priority in CANSIT registers. It is format-
ted to provide a direct entry for CANPAGE register. Because CANHPMOB codes CANSIT
registers, it will be only updated if the corresponding enable bits (ENRX, ENTX, ENERR) are
enabled (c.f.
To preserve register allocation, the CAN data buffer is seen such as a FIFO (with address
pointer accessible) into a MOb selection.This also allows to reduce the risks of un-controlled
accesses.
There is one FIFO per MOb. This FIFO is accessed into a MOb page thanks to the CAN mes-
sage register.
internal RxDcan
Examples:
Full filtering: to accept only ID = 0x317 in part A.
- ID MSK = 111 1111 1111
- ID TAG = 011 0001 0111
Partiel filtering: to accept ID from 0x310 up to 0x317 in part A.
- ID MSK = 111 1111 1000
- ID TAG = 011 0001 0xxx
No filtering: to accept all ID’s from 0x000 up to 0x7FF in part A.
- ID MSK = 000 0000 0000
- ID TAG = xxx xxxx xxxx
CANIDT Registers & CANCDMOB (MOb[i])
Figure
16-14).
14(33)
Rx Shift Register (internal)
Enable
Write
14(33)
13(31) - RB excluded
b
b
b
b
b
b
=
RB excluded
13(31)
1
ATmega32/64/M1/C1
CANIDM Registers (MOb[i])
13(31)
Hit MOb[i]
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