MC912DG128A Motorola, MC912DG128A Datasheet - Page 276

• Manufacturer Part Number: MC912DG128A
• Description: Microcontrollers
• Manufacturer: Motorola

Identifier Acceptance Filter
MSCAN Controller
MC68HC912DT128A Rev 2.0
276
the setting of the ABTAK flag whether the message was actually aborted
(ABTAK=1) or sent in the meantime (ABTAK=0).
A very flexible programmable generic identifier acceptance filter has
been introduced in order to reduce the CPU interrupt loading. The filter
is programmable to operate in four different modes:
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Two identifier acceptance filters, each to be applied to the full 29
bits of the identifier and to the following bits of the CAN frame:
RTR, IDE, SRR. This mode implements a two filters for a full
length CAN 2.0B compliant extended identifier.
how the first 32-bit filter bank (CIDAR0–3, CIDMR0–3) produces a
filter 0 hit. Similarly, the second filter bank (CIDAR4–7,
CIDMR4–7) produces a filter 1 hit.
Four identifier acceptance filters, each to be applied to a) the 11
bits of the identifier and the RTR bit of CAN 2.0A messages or b)
the 14 most significant bits of the identifier of CAN 2.0B
messages.
(CIDAR0–3, CIDMR0–3) produces filter 0 and 1 hits. Similarly, the
second filter bank (CIDAR4–7, CIDMR4–7) produces filter 2 and
3 hits.
Eight identifier acceptance filters, each to be applied to the first 8
bits of the identifier. This mode implements eight independent
filters for the first 8 bit of a CAN 2.0A compliant standard identifier
or of a CAN 2.0B compliant extended identifier.
how the first 32-bit filter bank (CIDAR0–3, CIDMR0–3) produces
filter 0 to 3 hits. Similarly, the second filter bank (CIDAR4–7,
CIDMR4–7) produces filter 4 to 7 hits.
Closed filter. No CAN message will be copied into the foreground
buffer RxFG, and the RXF flag will never be set.
MSCAN Controller
Figure 44
shows how the first 32-bit filter bank
Figure 43
Figure 45
MOTOROLA
shows
shows
8-mscan12