MC68HC12 Datasheet, PDF (332/478 Pages) Motorola, Inc – The MC68HC912DT128A microcontroller unit (MCU) is a 16-bit device composed of standard on-chip peripherals including a 16-bit central processing unit

MSCAN Controller
a transmit interrupt. The transmit interrupt handler software can tell from
the setting of the ABTAK flag whether the message was actually aborted
(ABTAK=1) or sent in the meantime (ABTAK=0).
18.5 Identifier Acceptance Filter
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:
• 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. Figure 18-3 shows
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.
Figure 18-4 shows how the first 32-bit filter bank (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. Figure 18-5 shows
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.
Technical Data
332
MSCAN Controller
MC68HC912DT128A — Rev 4.0
MOTOROLA