MC68HC08AZ32A Datasheet, PDF (334/456 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
MSCAN08 Controller (MSCAN08)
20.6.1 MSCAN Extended ID Rejected if Stuff Bit Between ID16 and ID15
For 32-bit and 16-bit identifier acceptance modes, an extended ID CAN
frame with a stuff bit between ID16 and ID15 can be erroneously
rejected, depending on IDAR0, IDAR1, and IDMR1.
Extended IDs (ID28-ID0) which generate a stuff bit between ID16 and
ID15:
IDAR0
IDAR1
IDAR2
IDAR3
******** ***1111x xxxxxxxx xxxxxxxx
where x = 0 or 1 (don’t care)
* = pattern for ID28 to ID18 (see following).
Affected extended IDs (ID28 - ID18) patterns:
a) xxxxxxxxx01 exceptions: 00000000001
01111100001
11111000001
xxxx1000001 except
b) xxxxx100000 exception: 01111100000
c) xxxx0111111 exception: 00000111111
d) x0111110000
e) 10000000000
f) 11111111111
g) 10000011111
When an affected ID is received, an incorrect value is compared to the
2nd byte of the filter (IDAR1 and IDAR5, plus IDAR3 and IDAR7 in 16-
bit mode). This incorrect value is the shift register contents before ID15
is shifted in (i.e. right shifted by 1).
20.6.1.1 Work- around
If the problematic IDs cannot be avoided, the workaround is to mask
certain bits with IDMR1 (and IDMR5, plus IDMR3 and IDMR7 in 16-bit
mode).
Technical Data
334
MC68HC08AZ32A — Rev 1.0
MSCAN08 Controller (MSCAN08)
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